diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-17 16:56:17 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-17 16:56:17 -0800 |
commit | fa7f578076a8814caa5371e9f4949e408140766d (patch) | |
tree | 8021be6f956e8a259523c394a01183797ce04422 /kernel/pid.c | |
parent | 2dcd9c71c1ffa9a036e09047f60e08383bb0abb6 (diff) | |
parent | d1b069f5febc850556cf49e9bb9092d3179c5be5 (diff) |
Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:
- a bit more MM
- procfs updates
- dynamic-debug fixes
- lib/ updates
- checkpatch
- epoll
- nilfs2
- signals
- rapidio
- PID management cleanup and optimization
- kcov updates
- sysvipc updates
- quite a few misc things all over the place
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (94 commits)
EXPERT Kconfig menu: fix broken EXPERT menu
include/asm-generic/topology.h: remove unused parent_node() macro
arch/tile/include/asm/topology.h: remove unused parent_node() macro
arch/sparc/include/asm/topology_64.h: remove unused parent_node() macro
arch/sh/include/asm/topology.h: remove unused parent_node() macro
arch/ia64/include/asm/topology.h: remove unused parent_node() macro
drivers/pcmcia/sa1111_badge4.c: avoid unused function warning
mm: add infrastructure for get_user_pages_fast() benchmarking
sysvipc: make get_maxid O(1) again
sysvipc: properly name ipc_addid() limit parameter
sysvipc: duplicate lock comments wrt ipc_addid()
sysvipc: unteach ids->next_id for !CHECKPOINT_RESTORE
initramfs: use time64_t timestamps
drivers/watchdog: make use of devm_register_reboot_notifier()
kernel/reboot.c: add devm_register_reboot_notifier()
kcov: update documentation
Makefile: support flag -fsanitizer-coverage=trace-cmp
kcov: support comparison operands collection
kcov: remove pointless current != NULL check
kernel/panic.c: add TAINT_AUX
...
Diffstat (limited to 'kernel/pid.c')
-rw-r--r-- | kernel/pid.c | 247 |
1 files changed, 45 insertions, 202 deletions
diff --git a/kernel/pid.c b/kernel/pid.c index 020dedbdf066..b13b624e2c49 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -39,11 +39,8 @@ #include <linux/proc_ns.h> #include <linux/proc_fs.h> #include <linux/sched/task.h> +#include <linux/idr.h> -#define pid_hashfn(nr, ns) \ - hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift) -static struct hlist_head *pid_hash; -static unsigned int pidhash_shift = 4; struct pid init_struct_pid = INIT_STRUCT_PID; int pid_max = PID_MAX_DEFAULT; @@ -53,15 +50,6 @@ int pid_max = PID_MAX_DEFAULT; int pid_max_min = RESERVED_PIDS + 1; int pid_max_max = PID_MAX_LIMIT; -static inline int mk_pid(struct pid_namespace *pid_ns, - struct pidmap *map, int off) -{ - return (map - pid_ns->pidmap)*BITS_PER_PAGE + off; -} - -#define find_next_offset(map, off) \ - find_next_zero_bit((map)->page, BITS_PER_PAGE, off) - /* * PID-map pages start out as NULL, they get allocated upon * first use and are never deallocated. This way a low pid_max @@ -70,11 +58,8 @@ static inline int mk_pid(struct pid_namespace *pid_ns, */ struct pid_namespace init_pid_ns = { .kref = KREF_INIT(2), - .pidmap = { - [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } - }, - .last_pid = 0, - .nr_hashed = PIDNS_HASH_ADDING, + .idr = IDR_INIT, + .pid_allocated = PIDNS_ADDING, .level = 0, .child_reaper = &init_task, .user_ns = &init_user_ns, @@ -101,138 +86,6 @@ EXPORT_SYMBOL_GPL(init_pid_ns); static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock); -static void free_pidmap(struct upid *upid) -{ - int nr = upid->nr; - struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE; - int offset = nr & BITS_PER_PAGE_MASK; - - clear_bit(offset, map->page); - atomic_inc(&map->nr_free); -} - -/* - * If we started walking pids at 'base', is 'a' seen before 'b'? - */ -static int pid_before(int base, int a, int b) -{ - /* - * This is the same as saying - * - * (a - base + MAXUINT) % MAXUINT < (b - base + MAXUINT) % MAXUINT - * and that mapping orders 'a' and 'b' with respect to 'base'. - */ - return (unsigned)(a - base) < (unsigned)(b - base); -} - -/* - * We might be racing with someone else trying to set pid_ns->last_pid - * at the pid allocation time (there's also a sysctl for this, but racing - * with this one is OK, see comment in kernel/pid_namespace.c about it). - * We want the winner to have the "later" value, because if the - * "earlier" value prevails, then a pid may get reused immediately. - * - * Since pids rollover, it is not sufficient to just pick the bigger - * value. We have to consider where we started counting from. - * - * 'base' is the value of pid_ns->last_pid that we observed when - * we started looking for a pid. - * - * 'pid' is the pid that we eventually found. - */ -static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid) -{ - int prev; - int last_write = base; - do { - prev = last_write; - last_write = cmpxchg(&pid_ns->last_pid, prev, pid); - } while ((prev != last_write) && (pid_before(base, last_write, pid))); -} - -static int alloc_pidmap(struct pid_namespace *pid_ns) -{ - int i, offset, max_scan, pid, last = pid_ns->last_pid; - struct pidmap *map; - - pid = last + 1; - if (pid >= pid_max) - pid = RESERVED_PIDS; - offset = pid & BITS_PER_PAGE_MASK; - map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; - /* - * If last_pid points into the middle of the map->page we - * want to scan this bitmap block twice, the second time - * we start with offset == 0 (or RESERVED_PIDS). - */ - max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset; - for (i = 0; i <= max_scan; ++i) { - if (unlikely(!map->page)) { - void *page = kzalloc(PAGE_SIZE, GFP_KERNEL); - /* - * Free the page if someone raced with us - * installing it: - */ - spin_lock_irq(&pidmap_lock); - if (!map->page) { - map->page = page; - page = NULL; - } - spin_unlock_irq(&pidmap_lock); - kfree(page); - if (unlikely(!map->page)) - return -ENOMEM; - } - if (likely(atomic_read(&map->nr_free))) { - for ( ; ; ) { - if (!test_and_set_bit(offset, map->page)) { - atomic_dec(&map->nr_free); - set_last_pid(pid_ns, last, pid); - return pid; - } - offset = find_next_offset(map, offset); - if (offset >= BITS_PER_PAGE) - break; - pid = mk_pid(pid_ns, map, offset); - if (pid >= pid_max) - break; - } - } - if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { - ++map; - offset = 0; - } else { - map = &pid_ns->pidmap[0]; - offset = RESERVED_PIDS; - if (unlikely(last == offset)) - break; - } - pid = mk_pid(pid_ns, map, offset); - } - return -EAGAIN; -} - -int next_pidmap(struct pid_namespace *pid_ns, unsigned int last) -{ - int offset; - struct pidmap *map, *end; - - if (last >= PID_MAX_LIMIT) - return -1; - - offset = (last + 1) & BITS_PER_PAGE_MASK; - map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE]; - end = &pid_ns->pidmap[PIDMAP_ENTRIES]; - for (; map < end; map++, offset = 0) { - if (unlikely(!map->page)) - continue; - offset = find_next_bit((map)->page, BITS_PER_PAGE, offset); - if (offset < BITS_PER_PAGE) - return mk_pid(pid_ns, map, offset); - } - return -1; -} - void put_pid(struct pid *pid) { struct pid_namespace *ns; @@ -265,8 +118,7 @@ void free_pid(struct pid *pid) for (i = 0; i <= pid->level; i++) { struct upid *upid = pid->numbers + i; struct pid_namespace *ns = upid->ns; - hlist_del_rcu(&upid->pid_chain); - switch(--ns->nr_hashed) { + switch (--ns->pid_allocated) { case 2: case 1: /* When all that is left in the pid namespace @@ -275,21 +127,20 @@ void free_pid(struct pid *pid) */ wake_up_process(ns->child_reaper); break; - case PIDNS_HASH_ADDING: + case PIDNS_ADDING: /* Handle a fork failure of the first process */ WARN_ON(ns->child_reaper); - ns->nr_hashed = 0; + ns->pid_allocated = 0; /* fall through */ case 0: schedule_work(&ns->proc_work); break; } + + idr_remove(&ns->idr, upid->nr); } spin_unlock_irqrestore(&pidmap_lock, flags); - for (i = 0; i <= pid->level; i++) - free_pidmap(pid->numbers + i); - call_rcu(&pid->rcu, delayed_put_pid); } @@ -308,8 +159,29 @@ struct pid *alloc_pid(struct pid_namespace *ns) tmp = ns; pid->level = ns->level; + for (i = ns->level; i >= 0; i--) { - nr = alloc_pidmap(tmp); + int pid_min = 1; + + idr_preload(GFP_KERNEL); + spin_lock_irq(&pidmap_lock); + + /* + * init really needs pid 1, but after reaching the maximum + * wrap back to RESERVED_PIDS + */ + if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS) + pid_min = RESERVED_PIDS; + + /* + * Store a null pointer so find_pid_ns does not find + * a partially initialized PID (see below). + */ + nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min, + pid_max, GFP_ATOMIC); + spin_unlock_irq(&pidmap_lock); + idr_preload_end(); + if (nr < 0) { retval = nr; goto out_free; @@ -334,12 +206,12 @@ struct pid *alloc_pid(struct pid_namespace *ns) upid = pid->numbers + ns->level; spin_lock_irq(&pidmap_lock); - if (!(ns->nr_hashed & PIDNS_HASH_ADDING)) + if (!(ns->pid_allocated & PIDNS_ADDING)) goto out_unlock; for ( ; upid >= pid->numbers; --upid) { - hlist_add_head_rcu(&upid->pid_chain, - &pid_hash[pid_hashfn(upid->nr, upid->ns)]); - upid->ns->nr_hashed++; + /* Make the PID visible to find_pid_ns. */ + idr_replace(&upid->ns->idr, pid, upid->nr); + upid->ns->pid_allocated++; } spin_unlock_irq(&pidmap_lock); @@ -350,8 +222,11 @@ out_unlock: put_pid_ns(ns); out_free: + spin_lock_irq(&pidmap_lock); while (++i <= ns->level) - free_pidmap(pid->numbers + i); + idr_remove(&ns->idr, (pid->numbers + i)->nr); + + spin_unlock_irq(&pidmap_lock); kmem_cache_free(ns->pid_cachep, pid); return ERR_PTR(retval); @@ -360,21 +235,13 @@ out_free: void disable_pid_allocation(struct pid_namespace *ns) { spin_lock_irq(&pidmap_lock); - ns->nr_hashed &= ~PIDNS_HASH_ADDING; + ns->pid_allocated &= ~PIDNS_ADDING; spin_unlock_irq(&pidmap_lock); } struct pid *find_pid_ns(int nr, struct pid_namespace *ns) { - struct upid *pnr; - - hlist_for_each_entry_rcu(pnr, - &pid_hash[pid_hashfn(nr, ns)], pid_chain) - if (pnr->nr == nr && pnr->ns == ns) - return container_of(pnr, struct pid, - numbers[ns->level]); - - return NULL; + return idr_find(&ns->idr, nr); } EXPORT_SYMBOL_GPL(find_pid_ns); @@ -530,6 +397,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, if (type != PIDTYPE_PID) { if (type == __PIDTYPE_TGID) type = PIDTYPE_PID; + task = task->group_leader; } nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns); @@ -553,35 +421,13 @@ EXPORT_SYMBOL_GPL(task_active_pid_ns); */ struct pid *find_ge_pid(int nr, struct pid_namespace *ns) { - struct pid *pid; - - do { - pid = find_pid_ns(nr, ns); - if (pid) - break; - nr = next_pidmap(ns, nr); - } while (nr > 0); - - return pid; -} - -/* - * The pid hash table is scaled according to the amount of memory in the - * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or - * more. - */ -void __init pidhash_init(void) -{ - pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18, - HASH_EARLY | HASH_SMALL | HASH_ZERO, - &pidhash_shift, NULL, - 0, 4096); + return idr_get_next(&ns->idr, &nr); } -void __init pidmap_init(void) +void __init pid_idr_init(void) { /* Verify no one has done anything silly: */ - BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING); + BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING); /* bump default and minimum pid_max based on number of cpus */ pid_max = min(pid_max_max, max_t(int, pid_max, @@ -590,10 +436,7 @@ void __init pidmap_init(void) PIDS_PER_CPU_MIN * num_possible_cpus()); pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min); - init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); - /* Reserve PID 0. We never call free_pidmap(0) */ - set_bit(0, init_pid_ns.pidmap[0].page); - atomic_dec(&init_pid_ns.pidmap[0].nr_free); + idr_init(&init_pid_ns.idr); init_pid_ns.pid_cachep = KMEM_CACHE(pid, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT); |