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2017-07-14kmod: add test driver to stress test the module loaderLuis R. Rodriguez
This adds a new stress test driver for kmod: the kernel module loader. The new stress test driver, test_kmod, is only enabled as a module right now. It should be possible to load this as built-in and load tests early (refer to the force_init_test module parameter), however since a lot of test can get a system out of memory fast we leave this disabled for now. Using a system with 1024 MiB of RAM can *easily* get your kernel OOM fast with this test driver. The test_kmod driver exposes API knobs for us to fine tune simple request_module() and get_fs_type() calls. Since these API calls only allow each one parameter a test driver for these is rather simple. Other factors that can help out test driver though are the number of calls we issue and knowing current limitations of each. This exposes configuration as much as possible through userspace to be able to build tests directly from userspace. Since it allows multiple misc devices its will eventually (once we add a knob to let us create new devices at will) also be possible to perform more tests in parallel, provided you have enough memory. We only enable tests we know work as of right now. Demo screenshots: # tools/testing/selftests/kmod/kmod.sh kmod_test_0001_driver: OK! - loading kmod test kmod_test_0001_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND kmod_test_0001_fs: OK! - loading kmod test kmod_test_0001_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL kmod_test_0002_driver: OK! - loading kmod test kmod_test_0002_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND kmod_test_0002_fs: OK! - loading kmod test kmod_test_0002_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL kmod_test_0003: OK! - loading kmod test kmod_test_0003: OK! - Return value: 0 (SUCCESS), expected SUCCESS kmod_test_0004: OK! - loading kmod test kmod_test_0004: OK! - Return value: 0 (SUCCESS), expected SUCCESS kmod_test_0005: OK! - loading kmod test kmod_test_0005: OK! - Return value: 0 (SUCCESS), expected SUCCESS kmod_test_0006: OK! - loading kmod test kmod_test_0006: OK! - Return value: 0 (SUCCESS), expected SUCCESS kmod_test_0005: OK! - loading kmod test kmod_test_0005: OK! - Return value: 0 (SUCCESS), expected SUCCESS kmod_test_0006: OK! - loading kmod test kmod_test_0006: OK! - Return value: 0 (SUCCESS), expected SUCCESS XXX: add test restult for 0007 Test completed You can also request for specific tests: # tools/testing/selftests/kmod/kmod.sh -t 0001 kmod_test_0001_driver: OK! - loading kmod test kmod_test_0001_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND kmod_test_0001_fs: OK! - loading kmod test kmod_test_0001_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL Test completed Lastly, the current available number of tests: # tools/testing/selftests/kmod/kmod.sh --help Usage: tools/testing/selftests/kmod/kmod.sh [ -t <4-number-digit> ] Valid tests: 0001-0009 0001 - Simple test - 1 thread for empty string 0002 - Simple test - 1 thread for modules/filesystems that do not exist 0003 - Simple test - 1 thread for get_fs_type() only 0004 - Simple test - 2 threads for get_fs_type() only 0005 - multithreaded tests with default setup - request_module() only 0006 - multithreaded tests with default setup - get_fs_type() only 0007 - multithreaded tests with default setup test request_module() and get_fs_type() 0008 - multithreaded - push kmod_concurrent over max_modprobes for request_module() 0009 - multithreaded - push kmod_concurrent over max_modprobes for get_fs_type() The following test cases currently fail, as such they are not currently enabled by default: # tools/testing/selftests/kmod/kmod.sh -t 0008 # tools/testing/selftests/kmod/kmod.sh -t 0009 To be sure to run them as intended please unload both of the modules: o test_module o xfs And ensure they are not loaded on your system prior to testing them. If you use these paritions for your rootfs you can change the default test driver used for get_fs_type() by exporting it into your environment. For example of other test defaults you can override refer to kmod.sh allow_user_defaults(). Behind the scenes this is how we fine tune at a test case prior to hitting a trigger to run it: cat /sys/devices/virtual/misc/test_kmod0/config echo -n "2" > /sys/devices/virtual/misc/test_kmod0/config_test_case echo -n "ext4" > /sys/devices/virtual/misc/test_kmod0/config_test_fs echo -n "80" > /sys/devices/virtual/misc/test_kmod0/config_num_threads cat /sys/devices/virtual/misc/test_kmod0/config echo -n "1" > /sys/devices/virtual/misc/test_kmod0/config_num_threads Finally to trigger: echo -n "1" > /sys/devices/virtual/misc/test_kmod0/trigger_config The kmod.sh script uses the above constructs to build different test cases. A bit of interpretation of the current failures follows, first two premises: a) When request_module() is used userspace figures out an optimized version of module order for us. Once it finds the modules it needs, as per depmod symbol dep map, it will finit_module() the respective modules which are needed for the original request_module() request. b) We have an optimization in place whereby if a kernel uses request_module() on a module already loaded we never bother userspace as the module already is loaded. This is all handled by kernel/kmod.c. A few things to consider to help identify root causes of issues: 0) kmod 19 has a broken heuristic for modules being assumed to be built-in to your kernel and will return 0 even though request_module() failed. Upgrade to a newer version of kmod. 1) A get_fs_type() call for "xfs" will request_module() for "fs-xfs", not for "xfs". The optimization in kernel described in b) fails to catch if we have a lot of consecutive get_fs_type() calls. The reason is the optimization in place does not look for aliases. This means two consecutive get_fs_type() calls will bump kmod_concurrent, whereas request_module() will not. This one explanation why test case 0009 fails at least once for get_fs_type(). 2) If a module fails to load --- for whatever reason (kmod_concurrent limit reached, file not yet present due to rootfs switch, out of memory) we have a period of time during which module request for the same name either with request_module() or get_fs_type() will *also* fail to load even if the file for the module is ready. This explains why *multiple* NULLs are possible on test 0009. 3) finit_module() consumes quite a bit of memory. 4) Filesystems typically also have more dependent modules than other modules, its important to note though that even though a get_fs_type() call does not incur additional kmod_concurrent bumps, since userspace loads dependencies it finds it needs via finit_module_fd(), it *will* take much more memory to load a module with a lot of dependencies. Because of 3) and 4) we will easily run into out of memory failures with certain tests. For instance test 0006 fails on qemu with 1024 MiB of RAM. It panics a box after reaping all userspace processes and still not having enough memory to reap. [arnd@arndb.de: add dependencies for test module] Link: http://lkml.kernel.org/r/20170630154834.3689272-1-arnd@arndb.de Link: http://lkml.kernel.org/r/20170628223155.26472-3-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Jessica Yu <jeyu@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Michal Marek <mmarek@suse.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12test_sysctl: add dedicated proc sysctl test driverLuis R. Rodriguez
The existing tools/testing/selftests/sysctl/ tests include two test cases, but these use existing production kernel sysctl interfaces. We want to expand test coverage but we can't just be looking for random safe production values to poke at, that's just insane! Instead just dedicate a test driver for debugging purposes and port the existing scripts to use it. This will make it easier for further tests to be added. Subsequent patches will extend our test coverage for sysctl. The stress test driver uses a new license (GPL on Linux, copyleft-next outside of Linux). Linus was fine with this [0] and later due to Ted's and Alans's request ironed out an "or" language clause to use [1] which is already present upstream. [0] https://lkml.kernel.org/r/CA+55aFyhxcvD+q7tp+-yrSFDKfR0mOHgyEAe=f_94aKLsOu0Og@mail.gmail.com [1] https://lkml.kernel.org/r/1495234558.7848.122.camel@linux.intel.com Link: http://lkml.kernel.org/r/20170630224431.17374-2-mcgrof@kernel.org Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-07Merge tag 'for-linus-v4.13-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux Pull Writeback error handling updates from Jeff Layton: "This pile represents the bulk of the writeback error handling fixes that I have for this cycle. Some of the earlier patches in this pile may look trivial but they are prerequisites for later patches in the series. The aim of this set is to improve how we track and report writeback errors to userland. Most applications that care about data integrity will periodically call fsync/fdatasync/msync to ensure that their writes have made it to the backing store. For a very long time, we have tracked writeback errors using two flags in the address_space: AS_EIO and AS_ENOSPC. Those flags are set when a writeback error occurs (via mapping_set_error) and are cleared as a side-effect of filemap_check_errors (as you noted yesterday). This model really sucks for userland. Only the first task to call fsync (or msync or fdatasync) will see the error. Any subsequent task calling fsync on a file will get back 0 (unless another writeback error occurs in the interim). If I have several tasks writing to a file and calling fsync to ensure that their writes got stored, then I need to have them coordinate with one another. That's difficult enough, but in a world of containerized setups that coordination may even not be possible. But wait...it gets worse! The calls to filemap_check_errors can be buried pretty far down in the call stack, and there are internal callers of filemap_write_and_wait and the like that also end up clearing those errors. Many of those callers ignore the error return from that function or return it to userland at nonsensical times (e.g. truncate() or stat()). If I get back -EIO on a truncate, there is no reason to think that it was because some previous writeback failed, and a subsequent fsync() will (incorrectly) return 0. This pile aims to do three things: 1) ensure that when a writeback error occurs that that error will be reported to userland on a subsequent fsync/fdatasync/msync call, regardless of what internal callers are doing 2) report writeback errors on all file descriptions that were open at the time that the error occurred. This is a user-visible change, but I think most applications are written to assume this behavior anyway. Those that aren't are unlikely to be hurt by it. 3) document what filesystems should do when there is a writeback error. Today, there is very little consistency between them, and a lot of cargo-cult copying. We need to make it very clear what filesystems should do in this situation. To achieve this, the set adds a new data type (errseq_t) and then builds new writeback error tracking infrastructure around that. Once all of that is in place, we change the filesystems to use the new infrastructure for reporting wb errors to userland. Note that this is just the initial foray into cleaning up this mess. There is a lot of work remaining here: 1) convert the rest of the filesystems in a similar fashion. Once the initial set is in, then I think most other fs' will be fairly simple to convert. Hopefully most of those can in via individual filesystem trees. 2) convert internal waiters on writeback to use errseq_t for detecting errors instead of relying on the AS_* flags. I have some draft patches for this for ext4, but they are not quite ready for prime time yet. This was a discussion topic this year at LSF/MM too. If you're interested in the gory details, LWN has some good articles about this: https://lwn.net/Articles/718734/ https://lwn.net/Articles/724307/" * tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux: btrfs: minimal conversion to errseq_t writeback error reporting on fsync xfs: minimal conversion to errseq_t writeback error reporting ext4: use errseq_t based error handling for reporting data writeback errors fs: convert __generic_file_fsync to use errseq_t based reporting block: convert to errseq_t based writeback error tracking dax: set errors in mapping when writeback fails Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors mm: set both AS_EIO/AS_ENOSPC and errseq_t in mapping_set_error fs: new infrastructure for writeback error handling and reporting lib: add errseq_t type and infrastructure for handling it mm: don't TestClearPageError in __filemap_fdatawait_range mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails jbd2: don't clear and reset errors after waiting on writeback buffer: set errors in mapping at the time that the error occurs fs: check for writeback errors after syncing out buffers in generic_file_fsync buffer: use mapping_set_error instead of setting the flag mm: fix mapping_set_error call in me_pagecache_dirty
2017-07-06lib: add errseq_t type and infrastructure for handling itJeff Layton
An errseq_t is a way of recording errors in one place, and allowing any number of "subscribers" to tell whether an error has been set again since a previous time. It's implemented as an unsigned 32-bit value that is managed with atomic operations. The low order bits are designated to hold an error code (max size of MAX_ERRNO). The upper bits are used as a counter. The API works with consumers sampling an errseq_t value at a particular point in time. Later, that value can be used to tell whether new errors have been set since that time. Note that there is a 1 in 512k risk of collisions here if new errors are being recorded frequently, since we have so few bits to use as a counter. To mitigate this, one bit is used as a flag to tell whether the value has been sampled since a new value was recorded. That allows us to avoid bumping the counter if no one has sampled it since it was last bumped. Later patches will build on this infrastructure to change how writeback errors are tracked in the kernel. Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: NeilBrown <neilb@suse.com> Reviewed-by: Jan Kara <jack@suse.cz>
2017-07-03Merge tag 'char-misc-4.13-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc Pull char/misc updates from Greg KH: "Here is the "big" char/misc driver patchset for 4.13-rc1. Lots of stuff in here, a large thunderbolt update, w1 driver header reorg, the new mux driver subsystem, google firmware driver updates, and a raft of other smaller things. Full details in the shortlog. All of these have been in linux-next for a while with the only reported issue being a merge problem with this tree and the jc-docs tree in the w1 documentation area" * tag 'char-misc-4.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (147 commits) misc: apds990x: Use sysfs_match_string() helper mei: drop unreachable code in mei_start mei: validate the message header only in first fragment. DocBook: w1: Update W1 file locations and names in DocBook mux: adg792a: always require I2C support nvmem: rockchip-efuse: add support for rk322x-efuse nvmem: core: add locking to nvmem_find_cell nvmem: core: Call put_device() in nvmem_unregister() nvmem: core: fix leaks on registration errors nvmem: correct Broadcom OTP controller driver writes w1: Add subsystem kernel public interface drivers/fsi: Add module license to core driver drivers/fsi: Use asynchronous slave mode drivers/fsi: Add hub master support drivers/fsi: Add SCOM FSI client device driver drivers/fsi/gpio: Add tracepoints for GPIO master drivers/fsi: Add GPIO based FSI master drivers/fsi: Document FSI master sysfs files in ABI drivers/fsi: Add error handling for slave drivers/fsi: Add tracepoints for low-level operations ...
2017-06-09lib: Add crc4 moduleJeremy Kerr
Add a little helper for crc4 calculations. This works 4-bits-at-a-time, using a simple table approach. We will need this in the FSI core code, as well as any master implementations that need to calculate CRCs in software. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Chris Bostic <cbostic@linux.vnet.ibm.com> Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-08rcu: Remove SPARSE_RCU_POINTER Kconfig optionPaul E. McKenney
The sparse-based checking for non-RCU accesses to RCU-protected pointers has been around for a very long time, and it is now the only type of sparse-based checking that is optional. This commit therefore makes it unconditional. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2017-05-08lib: add module support to linked list sorting testsGeert Uytterhoeven
Extract the linked list sorting test code into its own source file, to allow to compile it either to a loadable module, or builtin into the kernel. Link: http://lkml.kernel.org/r/1488287219-15832-4-git-send-email-geert@linux-m68k.org Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-02Merge branch 'linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 Pull crypto updates from Herbert Xu: "Here is the crypto update for 4.12: API: - Add batch registration for acomp/scomp - Change acomp testing to non-unique compressed result - Extend algorithm name limit to 128 bytes - Require setkey before accept(2) in algif_aead Algorithms: - Add support for deflate rfc1950 (zlib) Drivers: - Add accelerated crct10dif for powerpc - Add crc32 in stm32 - Add sha384/sha512 in ccp - Add 3des/gcm(aes) for v5 devices in ccp - Add Queue Interface (QI) backend support in caam - Add new Exynos RNG driver - Add ThunderX ZIP driver - Add driver for hardware random generator on MT7623 SoC" * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (101 commits) crypto: stm32 - Fix OF module alias information crypto: algif_aead - Require setkey before accept(2) crypto: scomp - add support for deflate rfc1950 (zlib) crypto: scomp - allow registration of multiple scomps crypto: ccp - Change ISR handler method for a v5 CCP crypto: ccp - Change ISR handler method for a v3 CCP crypto: crypto4xx - rename ce_ring_contol to ce_ring_control crypto: testmgr - Allow ecb(cipher_null) in FIPS mode Revert "crypto: arm64/sha - Add constant operand modifier to ASM_EXPORT" crypto: ccp - Disable interrupts early on unload crypto: ccp - Use only the relevant interrupt bits hwrng: mtk - Add driver for hardware random generator on MT7623 SoC dt-bindings: hwrng: Add Mediatek hardware random generator bindings crypto: crct10dif-vpmsum - Fix missing preempt_disable() crypto: testmgr - replace compression known answer test crypto: acomp - allow registration of multiple acomps hwrng: n2 - Use devm_kcalloc() in n2rng_probe() crypto: chcr - Fix error handling related to 'chcr_alloc_shash' padata: get_next is never NULL crypto: exynos - Add new Exynos RNG driver ...
2017-04-26CONFIG_ARCH_HAS_RAW_COPY_USER is unconditional nowAl Viro
all architectures converted Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-03-28generic ...copy_..._user primitivesAl Viro
provide raw_copy_..._user() and select ARCH_HAS_RAW_COPY_USER to use those. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-03-24md5: remove from lib and only live in cryptoJason A. Donenfeld
The md5_transform function is no longer used any where in the tree, except for the crypto api's actual implementation of md5, so we can drop the function from lib and put it as a static function of the crypto file, where it belongs. There should be no new users of md5_transform, anyway, since there are more modern ways of doing what it once achieved. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-02-28Merge branch 'idr-4.11' of git://git.infradead.org/users/willy/linux-daxLinus Torvalds
Pull IDR rewrite from Matthew Wilcox: "The most significant part of the following is the patch to rewrite the IDR & IDA to be clients of the radix tree. But there's much more, including an enhancement of the IDA to be significantly more space efficient, an IDR & IDA test suite, some improvements to the IDR API (and driver changes to take advantage of those improvements), several improvements to the radix tree test suite and RCU annotations. The IDR & IDA rewrite had a good spin in linux-next and Andrew's tree for most of the last cycle. Coupled with the IDR test suite, I feel pretty confident that any remaining bugs are quite hard to hit. 0-day did a great job of watching my git tree and pointing out problems; as it hit them, I added new test-cases to be sure not to be caught the same way twice" Willy goes on to expand a bit on the IDR rewrite rationale: "The radix tree and the IDR use very similar data structures. Merging the two codebases lets us share the memory allocation pools, and results in a net deletion of 500 lines of code. It also opens up the possibility of exposing more of the features of the radix tree to users of the IDR (and I have some interesting patches along those lines waiting for 4.12) It also shrinks the size of the 'struct idr' from 40 bytes to 24 which will shrink a fair few data structures that embed an IDR" * 'idr-4.11' of git://git.infradead.org/users/willy/linux-dax: (32 commits) radix tree test suite: Add config option for map shift idr: Add missing __rcu annotations radix-tree: Fix __rcu annotations radix-tree: Add rcu_dereference and rcu_assign_pointer calls radix tree test suite: Run iteration tests for longer radix tree test suite: Fix split/join memory leaks radix tree test suite: Fix leaks in regression2.c radix tree test suite: Fix leaky tests radix tree test suite: Enable address sanitizer radix_tree_iter_resume: Fix out of bounds error radix-tree: Store a pointer to the root in each node radix-tree: Chain preallocated nodes through ->parent radix tree test suite: Dial down verbosity with -v radix tree test suite: Introduce kmalloc_verbose idr: Return the deleted entry from idr_remove radix tree test suite: Build separate binaries for some tests ida: Use exceptional entries for small IDAs ida: Move ida_bitmap to a percpu variable Reimplement IDR and IDA using the radix tree radix-tree: Add radix_tree_iter_delete ...
2017-02-28Merge branch 'locking-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Ingo Molnar: "The main change is the uninlining of large refcount_t APIs, plus a header dependency fix. Note that the uninlining allowed us to enable the underflow/overflow warnings unconditionally and remove the debug Kconfig switch: this might trigger new warnings in buggy code and turn crashes/use-after-free bugs into less harmful memory leaks" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/refcounts: Add missing kernel.h header to have UINT_MAX defined locking/refcounts: Out-of-line everything
2017-02-25Merge tag 'for-next-dma_ops' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma Pull rdma DMA mapping updates from Doug Ledford: "Drop IB DMA mapping code and use core DMA code instead. Bart Van Assche noted that the ib DMA mapping code was significantly similar enough to the core DMA mapping code that with a few changes it was possible to remove the IB DMA mapping code entirely and switch the RDMA stack to use the core DMA mapping code. This resulted in a nice set of cleanups, but touched the entire tree and has been kept separate for that reason." * tag 'for-next-dma_ops' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma: (37 commits) IB/rxe, IB/rdmavt: Use dma_virt_ops instead of duplicating it IB/core: Remove ib_device.dma_device nvme-rdma: Switch from dma_device to dev.parent RDS: net: Switch from dma_device to dev.parent IB/srpt: Modify a debug statement IB/srp: Switch from dma_device to dev.parent IB/iser: Switch from dma_device to dev.parent IB/IPoIB: Switch from dma_device to dev.parent IB/rxe: Switch from dma_device to dev.parent IB/vmw_pvrdma: Switch from dma_device to dev.parent IB/usnic: Switch from dma_device to dev.parent IB/qib: Switch from dma_device to dev.parent IB/qedr: Switch from dma_device to dev.parent IB/ocrdma: Switch from dma_device to dev.parent IB/nes: Remove a superfluous assignment statement IB/mthca: Switch from dma_device to dev.parent IB/mlx5: Switch from dma_device to dev.parent IB/mlx4: Switch from dma_device to dev.parent IB/i40iw: Remove a superfluous assignment statement IB/hns: Switch from dma_device to dev.parent ...
2017-02-24lib: add CONFIG_TEST_SORT to enable self-test of sort()Kostenzer Felix
Along with the addition made to Kconfig.debug, the prior existing but permanently disabled test function has been slightly refactored. Patch has been tested using QEMU 2.1.2 with a .config obtained through 'make defconfig' (x86_64) and manually enabling the option. [arnd@arndb.de: move sort self-test into a separate file] Link: http://lkml.kernel.org/r/20170112110657.3123790-1-arnd@arndb.de Link: http://lkml.kernel.org/r/HE1PR09MB0394B0418D504DCD27167D4FD49B0@HE1PR09MB0394.eurprd09.prod.outlook.com Signed-off-by: Kostenzer Felix <fkostenzer@live.at> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24lib: add module support to glob testsGeert Uytterhoeven
Extract the glob test code into its own source file, to allow to compile it either to a loadable module, or builtin into the kernel. Link: http://lkml.kernel.org/r/1483470276-10517-2-git-send-email-geert@linux-m68k.org Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24lib: add module support to crc32 testsGeert Uytterhoeven
Extract the crc32 test code into its own source file, to allow to compile it either to a loadable module, or builtin into the kernel. Link: http://lkml.kernel.org/r/1483470276-10517-1-git-send-email-geert@linux-m68k.org Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24locking/refcounts: Out-of-line everythingPeter Zijlstra
Linus asked to please make this real C code. And since size then isn't an issue what so ever anymore, remove the debug knob and make all WARN()s unconditional. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dwindsor@gmail.com Cc: elena.reshetova@intel.com Cc: gregkh@linuxfoundation.org Cc: ishkamiel@gmail.com Cc: keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-23Merge tag 'drm-for-v4.11-less-shouty' of ↵Linus Torvalds
git://people.freedesktop.org/~airlied/linux Pull drm updates from Dave Airlie: "This is the main drm pull request for v4.11. Nothing too major, the tinydrm and mmu-less support should make writing smaller drivers easier for some of the simpler platforms, and there are a bunch of documentation updates. Intel grew displayport MST audio support which is hopefully useful to people, and FBC is on by default for GEN9+ (so people know where to look for regressions). AMDGPU has a lot of fixes that would like new firmware files installed for some GPUs. Other than that it's pretty scattered all over. I may have a follow up pull request as I know BenH has a bunch of AST rework and fixes and I'd like to get those in once they've been tested by AST, and I've got at least one pull request I'm just trying to get the author to fix up. Core: - drm_mm reworked - Connector list locking and iterators - Documentation updates - Format handling rework - MMU-less support for fbdev helpers - drm_crtc_from_index helper - Core CRC API - Remove drm_framebuffer_unregister_private - Debugfs cleanup - EDID/Infoframe fixes - Release callback - Tinydrm support (smaller drivers for simple hw) panel: - Add support for some new simple panels i915: - FBC by default for gen9+ - Shared dpll cleanups and docs - GEN8 powerdomain cleanup - DMC support on GLK - DP MST audio support - HuC loading support - GVT init ordering fixes - GVT IOMMU workaround fix amdgpu/radeon: - Power/clockgating improvements - Preliminary SR-IOV support - TTM buffer priority and eviction fixes - SI DPM quirks removed due to firmware fixes - Powerplay improvements - VCE/UVD powergating fixes - Cleanup SI GFX code to match CI/VI - Support for > 2 displays on 3/5 crtc asics - SI headless fixes nouveau: - Rework securre boot code in prep for GP10x secure boot - Channel recovery improvements - Initial power budget code - MMU rework preperation vmwgfx: - Bunch of fixes and cleanups exynos: - Runtime PM support for MIC driver - Cleanups to use atomic helpers - UHD Support for TM2/TM2E boards - Trigger mode fix for Rinato board etnaviv: - Shader performance fix - Command stream validator fixes - Command buffer suballocator rockchip: - CDN DisplayPort support - IOMMU support for arm64 platform imx-drm: - Fix i.MX5 TV encoder probing - Remove lower fb size limits msm: - Support for HW cursor on MDP5 devices - DSI encoder cleanup - GPU DT bindings cleanup sti: - stih410 cleanups - Create fbdev at binding - HQVDP fixes - Remove stih416 chip functionality - DVI/HDMI mode selection fixes - FPS statistic reporting omapdrm: - IRQ code cleanup dwi-hdmi bridge: - Cleanups and fixes adv-bridge: - Updates for nexus sii8520 bridge: - Add interlace mode support - Rework HDMI and lots of fixes qxl: - probing/teardown cleanups ZTE drm: - HDMI audio via SPDIF interface - Video Layer overlay plane support - Add TV encoder output device atmel-hlcdc: - Rework fbdev creation logic tegra: - OF node fix fsl-dcu: - Minor fixes mali-dp: - Assorted fixes sunxi: - Minor fix" [ This was the "fixed" pull, that still had build warnings due to people not even having build tested the result. I'm not a happy camper I've fixed the things I noticed up in this merge. - Linus ] * tag 'drm-for-v4.11-less-shouty' of git://people.freedesktop.org/~airlied/linux: (1177 commits) lib/Kconfig: make PRIME_NUMBERS not user selectable drm/tinydrm: helpers: Properly fix backlight dependency drm/tinydrm: mipi-dbi: Fix field width specifier warning drm/tinydrm: mipi-dbi: Silence: ‘cmd’ may be used uninitialized drm/sti: fix build warnings in sti_drv.c and sti_vtg.c files drm/amd/powerplay: fix PSI feature on Polars12 drm/amdgpu: refuse to reserve io mem for split VRAM buffers drm/ttm: fix use-after-free races in vm fault handling drm/tinydrm: Add support for Multi-Inno MI0283QT display dt-bindings: Add Multi-Inno MI0283QT binding dt-bindings: display/panel: Add common rotation property of: Add vendor prefix for Multi-Inno drm/tinydrm: Add MIPI DBI support drm/tinydrm: Add helper functions drm: Add DRM support for tiny LCD displays drm/amd/amdgpu: post card if there is real hw resetting performed drm/nouveau/tmr: provide backtrace when a timeout is hit drm/nouveau/pci/g92: Fix rearm drm/nouveau/drm/therm/fan: add a fallback if no fan control is specified in the vbios drm/nouveau/hwmon: expose power_max and power_crit ..
2017-02-22Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds
Pull networking updates from David Miller: "Highlights: 1) Support TX_RING in AF_PACKET TPACKET_V3 mode, from Sowmini Varadhan. 2) Simplify classifier state on sk_buff in order to shrink it a bit. From Willem de Bruijn. 3) Introduce SIPHASH and it's usage for secure sequence numbers and syncookies. From Jason A. Donenfeld. 4) Reduce CPU usage for ICMP replies we are going to limit or suppress, from Jesper Dangaard Brouer. 5) Introduce Shared Memory Communications socket layer, from Ursula Braun. 6) Add RACK loss detection and allow it to actually trigger fast recovery instead of just assisting after other algorithms have triggered it. From Yuchung Cheng. 7) Add xmit_more and BQL support to mvneta driver, from Simon Guinot. 8) skb_cow_data avoidance in esp4 and esp6, from Steffen Klassert. 9) Export MPLS packet stats via netlink, from Robert Shearman. 10) Significantly improve inet port bind conflict handling, especially when an application is restarted and changes it's setting of reuseport. From Josef Bacik. 11) Implement TX batching in vhost_net, from Jason Wang. 12) Extend the dummy device so that VF (virtual function) features, such as configuration, can be more easily tested. From Phil Sutter. 13) Avoid two atomic ops per page on x86 in bnx2x driver, from Eric Dumazet. 14) Add new bpf MAP, implementing a longest prefix match trie. From Daniel Mack. 15) Packet sample offloading support in mlxsw driver, from Yotam Gigi. 16) Add new aquantia driver, from David VomLehn. 17) Add bpf tracepoints, from Daniel Borkmann. 18) Add support for port mirroring to b53 and bcm_sf2 drivers, from Florian Fainelli. 19) Remove custom busy polling in many drivers, it is done in the core networking since 4.5 times. From Eric Dumazet. 20) Support XDP adjust_head in virtio_net, from John Fastabend. 21) Fix several major holes in neighbour entry confirmation, from Julian Anastasov. 22) Add XDP support to bnxt_en driver, from Michael Chan. 23) VXLAN offloads for enic driver, from Govindarajulu Varadarajan. 24) Add IPVTAP driver (IP-VLAN based tap driver) from Sainath Grandhi. 25) Support GRO in IPSEC protocols, from Steffen Klassert" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1764 commits) Revert "ath10k: Search SMBIOS for OEM board file extension" net: socket: fix recvmmsg not returning error from sock_error bnxt_en: use eth_hw_addr_random() bpf: fix unlocking of jited image when module ronx not set arch: add ARCH_HAS_SET_MEMORY config net: napi_watchdog() can use napi_schedule_irqoff() tcp: Revert "tcp: tcp_probe: use spin_lock_bh()" net/hsr: use eth_hw_addr_random() net: mvpp2: enable building on 64-bit platforms net: mvpp2: switch to build_skb() in the RX path net: mvpp2: simplify MVPP2_PRS_RI_* definitions net: mvpp2: fix indentation of MVPP2_EXT_GLOBAL_CTRL_DEFAULT net: mvpp2: remove unused register definitions net: mvpp2: simplify mvpp2_bm_bufs_add() net: mvpp2: drop useless fields in mvpp2_bm_pool and related code net: mvpp2: remove unused 'tx_skb' field of 'struct mvpp2_tx_queue' net: mvpp2: release reference to txq_cpu[] entry after unmapping net: mvpp2: handle too large value in mvpp2_rx_time_coal_set() net: mvpp2: handle too large value handling in mvpp2_rx_pkts_coal_set() net: mvpp2: remove useless arguments in mvpp2_rx_{pkts, time}_coal_set ...
2017-02-13idr: Add missing __rcu annotationsMatthew Wilcox
Where we use the radix tree iteration macros, we need to annotate 'slot' with __rcu. Make sure we don't forget any new places in the future with the same CFLAGS check used for radix-tree.c. Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
2017-02-13radix-tree: Fix __rcu annotationsMatthew Wilcox
Many places were missing __rcu annotations. A few places needed a few lines of explanation about why it was safe to not use RCU accessors. Add a custom CFLAGS setting to the Makefile to ensure that new patches don't miss RCU annotations. Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
2017-02-03lib: Introduce priority array area managerJiri Pirko
This introduces a infrastructure for management of linear priority areas. Priority order in an array matters, however order of items inside a priority group does not matter. As an initial implementation, L-sort algorithm is used. It is quite trivial. More advanced algorithm called P-sort will be introduced as a follow-up. The infrastructure is prepared for other algos. Alongside this, a testing module is introduced as well. Signed-off-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-02ext4: move halfmd4 into hash.c directlyJason A. Donenfeld
The "half md4" transform should not be used by any new code. And fortunately, it's only used now by ext4. Since ext4 supports several hashing methods, at some point it might be desirable to move to something like SipHash. As an intermediate step, remove half md4 from cryptohash.h and lib, and make it just a local function in ext4's hash.c. There's precedent for doing this; the other function ext can use for its hashes -- TEA -- is also implemented in the same place. Also, by being a local function, this might allow gcc to perform some additional optimizations. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-01-24lib/dma-virt: Add dma_virt_opsBart Van Assche
Several RDMA drivers (hfi1, qib and rxe) expect that ib_sge.addr is a virtual address. Provide DMA mapping operations that are suitable for these drivers. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Doug Ledford <dledford@redhat.com>
2017-01-24lib/dma-noop: Only build dma_noop_ops for s390 and m32rBart Van Assche
Reduce the kernel size by only building dma_noop_ops for those architectures that actually use it. This was suggested by Christoph Hellwig. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Doug Ledford <dledford@redhat.com>
2017-01-09siphash: add cryptographically secure PRFJason A. Donenfeld
SipHash is a 64-bit keyed hash function that is actually a cryptographically secure PRF, like HMAC. Except SipHash is super fast, and is meant to be used as a hashtable keyed lookup function, or as a general PRF for short input use cases, such as sequence numbers or RNG chaining. For the first usage: There are a variety of attacks known as "hashtable poisoning" in which an attacker forms some data such that the hash of that data will be the same, and then preceeds to fill up all entries of a hashbucket. This is a realistic and well-known denial-of-service vector. Currently hashtables use jhash, which is fast but not secure, and some kind of rotating key scheme (or none at all, which isn't good). SipHash is meant as a replacement for jhash in these cases. There are a modicum of places in the kernel that are vulnerable to hashtable poisoning attacks, either via userspace vectors or network vectors, and there's not a reliable mechanism inside the kernel at the moment to fix it. The first step toward fixing these issues is actually getting a secure primitive into the kernel for developers to use. Then we can, bit by bit, port things over to it as deemed appropriate. While SipHash is extremely fast for a cryptographically secure function, it is likely a bit slower than the insecure jhash, and so replacements will be evaluated on a case-by-case basis based on whether or not the difference in speed is negligible and whether or not the current jhash usage poses a real security risk. For the second usage: A few places in the kernel are using MD5 or SHA1 for creating secure sequence numbers, syn cookies, port numbers, or fast random numbers. SipHash is a faster and more fitting, and more secure replacement for MD5 in those situations. Replacing MD5 and SHA1 with SipHash for these uses is obvious and straight-forward, and so is submitted along with this patch series. There shouldn't be much of a debate over its efficacy. Dozens of languages are already using this internally for their hash tables and PRFs. Some of the BSDs already use this in their kernels. SipHash is a widely known high-speed solution to a widely known set of problems, and it's time we catch-up. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-09Merge tag 'drm-misc-next-2016-12-30' of ↵Dave Airlie
git://anongit.freedesktop.org/git/drm-misc into drm-next First -misc pull for 4.11: - drm_mm rework + lots of selftests (Chris Wilson) - new connector_list locking+iterators - plenty of kerneldoc updates - format handling rework from Ville - atomic helper changes from Maarten for better plane corner-case handling in drivers, plus the i915 legacy cursor patch that needs this - bridge cleanup from Laurent - plus plenty of small stuff all over - also contains a merge of the 4.10 docs tree so that we could apply the dma-buf kerneldoc patches It's a lot more than usual, but due to the merge window blackout it also covers about 4 weeks, so all in line again on a per-week basis. The more annoying part with no pull request for 4 weeks is managing cross-tree work. The -intel pull request I'll follow up with does conflict quite a bit with -misc here. Longer-term (if drm-misc keeps growing) a drm-next-queued to accept pull request for the next merge window during this time might be useful. I'd also like to backmerge -rc2+this into drm-intel next week, we have quite a pile of patches waiting for the stuff in here. * tag 'drm-misc-next-2016-12-30' of git://anongit.freedesktop.org/git/drm-misc: (126 commits) drm: Add kerneldoc markup for new @scan parameters in drm_mm drm/mm: Document locking rules drm: Use drm_mm_insert_node_in_range_generic() for everyone drm: Apply range restriction after color adjustment when allocation drm: Wrap drm_mm_node.hole_follows drm: Apply tight eviction scanning to color_adjust drm: Simplify drm_mm scan-list manipulation drm: Optimise power-of-two alignments in drm_mm_scan_add_block() drm: Compute tight evictions for drm_mm_scan drm: Fix application of color vs range restriction when scanning drm_mm drm: Unconditionally do the range check in drm_mm_scan_add_block() drm: Rename prev_node to hole in drm_mm_scan_add_block() drm: Fix O= out-of-tree builds for selftests drm: Extract struct drm_mm_scan from struct drm_mm drm: Add asserts to catch overflow in drm_mm_init() and drm_mm_init_scan() drm: Simplify drm_mm_clean() drm: Detect overflow in drm_mm_reserve_node() drm: Fix kerneldoc for drm_mm_scan_remove_block() drm: Promote drm_mm alignment to u64 drm: kselftest for drm_mm and restricted color eviction ...
2016-12-27lib: Add a simple prime number generatorChris Wilson
Prime numbers are interesting for testing components that use multiplies and divides, such as testing DRM's struct drm_mm alignment computations. v2: Move to lib/, add selftest v3: Fix initial constants (exclude 0/1 from being primes) v4: More RCU markup to keep 0day/sparse happy v5: Fix RCU unwind on module exit, add to kselftests v6: Tidy computation of bitmap size v7: for_each_prime_number_from() v8: Compose small-primes using BIT() for easier verification v9: Move rcu dance entirely into callers. v10: Improve quote for Betrand's Postulate (aka Chebyshev's theorem) Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Lukas Wunner <lukas@wunner.de> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20161222144514.3911-1-chris@chris-wilson.co.uk
2016-12-25cpu/hotplug: Remove obsolete cpu hotplug register/unregister functionsThomas Gleixner
hotcpu_notifier(), cpu_notifier(), __hotcpu_notifier(), __cpu_notifier(), register_hotcpu_notifier(), register_cpu_notifier(), __register_hotcpu_notifier(), __register_cpu_notifier(), unregister_hotcpu_notifier(), unregister_cpu_notifier(), __unregister_hotcpu_notifier(), __unregister_cpu_notifier() are unused now. Remove them and all related code. Remove also the now pointless cpu notifier error injection mechanism. The states can be executed step by step and error rollback is the same as cpu down, so any state transition can be tested w/o requiring the notifier error injection. Some CPU hotplug states are kept as they are (ab)used for hotplug state tracking. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161221192112.005642358@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-10-11kcov: do not instrument lib/stackdepot.cAlexander Potapenko
There's no point in collecting coverage from lib/stackdepot.c, as it is not a function of syscall inputs. Disabling kcov instrumentation for that file will reduce the coverage noise level. Link: http://lkml.kernel.org/r/1474640972-104131-1-git-send-email-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: syzkaller <syzkaller@googlegroups.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07Merge branch 'for-4.9/block' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block layer updates from Jens Axboe: "This is the main pull request for block layer changes in 4.9. As mentioned at the last merge window, I've changed things up and now do just one branch for core block layer changes, and driver changes. This avoids dependencies between the two branches. Outside of this main pull request, there are two topical branches coming as well. This pull request contains: - A set of fixes, and a conversion to blk-mq, of nbd. From Josef. - Set of fixes and updates for lightnvm from Matias, Simon, and Arnd. Followup dependency fix from Geert. - General fixes from Bart, Baoyou, Guoqing, and Linus W. - CFQ async write starvation fix from Glauber. - Add supprot for delayed kick of the requeue list, from Mike. - Pull out the scalable bitmap code from blk-mq-tag.c and make it generally available under the name of sbitmap. Only blk-mq-tag uses it for now, but the blk-mq scheduling bits will use it as well. From Omar. - bdev thaw error progagation from Pierre. - Improve the blk polling statistics, and allow the user to clear them. From Stephen. - Set of minor cleanups from Christoph in block/blk-mq. - Set of cleanups and optimizations from me for block/blk-mq. - Various nvme/nvmet/nvmeof fixes from the various folks" * 'for-4.9/block' of git://git.kernel.dk/linux-block: (54 commits) fs/block_dev.c: return the right error in thaw_bdev() nvme: Pass pointers, not dma addresses, to nvme_get/set_features() nvme/scsi: Remove power management support nvmet: Make dsm number of ranges zero based nvmet: Use direct IO for writes admin-cmd: Added smart-log command support. nvme-fabrics: Add host_traddr options field to host infrastructure nvme-fabrics: revise host transport option descriptions nvme-fabrics: rework nvmf_get_address() for variable options nbd: use BLK_MQ_F_BLOCKING blkcg: Annotate blkg_hint correctly cfq: fix starvation of asynchronous writes blk-mq: add flag for drivers wanting blocking ->queue_rq() blk-mq: remove non-blocking pass in blk_mq_map_request blk-mq: get rid of manual run of queue with __blk_mq_run_hw_queue() block: export bio_free_pages to other modules lightnvm: propagate device_add() error code lightnvm: expose device geometry through sysfs lightnvm: control life of nvm_dev in driver blk-mq: register device instead of disk ...
2016-09-21lib/win_minmax: windowed min or max estimatorNeal Cardwell
This commit introduces a generic library to estimate either the min or max value of a time-varying variable over a recent time window. This is code originally from Kathleen Nichols. The current form of the code is from Van Jacobson. A single struct minmax_sample will track the estimated windowed-max value of the series if you call minmax_running_max() or the estimated windowed-min value of the series if you call minmax_running_min(). Nearly equivalent code is already in place for minimum RTT estimation in the TCP stack. This commit extracts that code and generalizes it to handle both min and max. Moving the code here reduces the footprint and complexity of the TCP code base and makes the filter generally available for other parts of the codebase, including an upcoming TCP congestion control module. This library works well for time series where the measurements are smoothly increasing or decreasing. Signed-off-by: Van Jacobson <vanj@google.com&g