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Linux Kernel patch submission checklist
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here are some basic things that developers should do if they want to see their
kernel patch submissions accepted more quickly.

These are all above and beyond the documentation that is provided in
Documentation/SubmittingPatches and elsewhere regarding submitting Linux
kernel patches.


1: If you use a facility then #include the file that defines/declares
   that facility.  Don't depend on other header files pulling in ones
   that you use.

2: Builds cleanly with applicable or modified CONFIG options =y, =m, and
   =n.  No gcc warnings/errors, no linker warnings/errors.

2b: Passes allnoconfig, allmodconfig

2c: Builds successfully when using O=builddir

3: Builds on multiple CPU architectures by using local cross-compile tools
   or some other build farm.

4: ppc64 is a good architecture for cross-compilation checking because it
   tends to use `unsigned long' for 64-bit quantities.

5: Check your patch for general style as detailed in
   Documentation/CodingStyle.  Check for trivial violations with the
   patch style checker prior to submission (scripts/checkpatch.pl).
   You should be able to justify all violations that remain in
   your patch.

6: Any new or modified CONFIG options don't muck up the config menu.

7: All new Kconfig options have help text.

8: Has been carefully reviewed with respect to relevant Kconfig
   combinations.  This is very hard to get right with testing -- brainpower
   pays off here.

9: Check cleanly with sparse.

10: Use 'make checkstack' and 'make namespacecheck' and fix any problems
    that they find.  Note: checkstack does not point out problems explicitly,
    but any one function that uses more than 512 bytes on the stack is a
    candidate for change.

11: Include kernel-doc to document global kernel APIs.  (Not required for
    static functions, but OK there also.) Use 'make htmldocs' or 'make
    mandocs' to check the kernel-doc and fix any issues.

12: Has been tested with CONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT,
    CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES,
    CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_ATOMIC_SLEEP, CONFIG_PROVE_RCU
    and CONFIG_DEBUG_OBJECTS_RCU_HEAD all simultaneously enabled.

13: Has been build- and runtime tested with and without CONFIG_SMP and
    CONFIG_PREEMPT.

14: If the patch affects IO/Disk, etc: has been tested with and without
    CONFIG_LBDAF.

15: All codepaths have been exercised with all lockdep features enabled.

16: All new /proc entries are documented under Documentation/

17: All new kernel boot parameters are documented in
    Documentation/kernel-parameters.txt.

18: All new module parameters are documented with MODULE_PARM_DESC()

19: All new userspace interfaces are documented in Documentation/ABI/.
    See Documentation/ABI/README for more information.
    Patches that change userspace interfaces should be CCed to
    linux-api@vger.kernel.org.

20: Check that it all passes `make headers_check'.

21: Has been checked with injection of at least slab and page-allocation
    failures.  See Documentation/fault-injection/.

    If the new code is substantial, addition of subsystem-specific fault
    injection might be appropriate.

22: Newly-added code has been compiled with `gcc -W' (use "make
    EXTRA_CFLAGS=-W").  This will generate lots of noise, but is good for
    finding bugs like "warning: comparison between signed and unsigned".

23: Tested after it has been merged into the -mm patchset to make sure
    that it still works with all of the other queued patches and various
    changes in the VM, VFS, and other subsystems.

24: All memory barriers {e.g., barrier(), rmb(), wmb()} need a comment in the
    source code that explains the logic of what they are doing and why.

25: If any ioctl's are added by the patch, then also update
    Documentation/ioctl/ioctl-number.txt.

26: If your modified source code depends on or uses any of the kernel
    APIs or features that are related to the following kconfig symbols,
    then test multiple builds with the related kconfig symbols disabled
    and/or =m (if that option is available) [not all of these at the
    same time, just various/random combinations of them]:

    CONFIG_SMP, CONFIG_SYSFS, CONFIG_PROC_FS, CONFIG_INPUT, CONFIG_PCI,
    CONFIG_BLOCK, CONFIG_PM, CONFIG_HOTPLUG, CONFIG_MAGIC_SYSRQ,
    CONFIG_NET, CONFIG_INET=n (but latter with CONFIG_NET=y)
'>410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *
 * Copyright (c) 2011, Microsoft Corporation.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *   K. Y. Srinivasan <kys@microsoft.com>
 */

#ifndef _HYPERV_VMBUS_H
#define _HYPERV_VMBUS_H

#include <linux/list.h>
#include <asm/sync_bitops.h>
#include <asm/hyperv-tlfs.h>
#include <linux/atomic.h>
#include <linux/hyperv.h>
#include <linux/interrupt.h>

#include "hv_trace.h"

/*
 * Timeout for services such as KVP and fcopy.
 */
#define HV_UTIL_TIMEOUT 30

/*
 * Timeout for guest-host handshake for services.
 */
#define HV_UTIL_NEGO_TIMEOUT 55


/* Definitions for the monitored notification facility */
union hv_monitor_trigger_group {
	u64 as_uint64;
	struct {
		u32 pending;
		u32 armed;
	};
};

struct hv_monitor_parameter {
	union hv_connection_id connectionid;
	u16 flagnumber;
	u16 rsvdz;
};

union hv_monitor_trigger_state {
	u32 asu32;

	struct {
		u32 group_enable:4;
		u32 rsvdz:28;
	};
};

/* struct hv_monitor_page Layout */
/* ------------------------------------------------------ */
/* | 0   | TriggerState (4 bytes) | Rsvd1 (4 bytes)     | */
/* | 8   | TriggerGroup[0]                              | */
/* | 10  | TriggerGroup[1]                              | */
/* | 18  | TriggerGroup[2]                              | */
/* | 20  | TriggerGroup[3]                              | */
/* | 28  | Rsvd2[0]                                     | */
/* | 30  | Rsvd2[1]                                     | */
/* | 38  | Rsvd2[2]                                     | */
/* | 40  | NextCheckTime[0][0]    | NextCheckTime[0][1] | */
/* | ...                                                | */
/* | 240 | Latency[0][0..3]                             | */
/* | 340 | Rsvz3[0]                                     | */
/* | 440 | Parameter[0][0]                              | */
/* | 448 | Parameter[0][1]                              | */
/* | ...                                                | */
/* | 840 | Rsvd4[0]                                     | */
/* ------------------------------------------------------ */
struct hv_monitor_page {
	union hv_monitor_trigger_state trigger_state;
	u32 rsvdz1;

	union hv_monitor_trigger_group trigger_group[4];
	u64 rsvdz2[3];

	s32 next_checktime[4][32];

	u16 latency[4][32];
	u64 rsvdz3[32];

	struct hv_monitor_parameter parameter[4][32];

	u8 rsvdz4[1984];
};

#define HV_HYPERCALL_PARAM_ALIGN	sizeof(u64)

/* Definition of the hv_post_message hypercall input structure. */
struct hv_input_post_message {
	union hv_connection_id connectionid;
	u32 reserved;
	u32 message_type;
	u32 payload_size;
	u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
};


enum {
	VMBUS_MESSAGE_CONNECTION_ID	= 1,
	VMBUS_MESSAGE_CONNECTION_ID_4	= 4,
	VMBUS_MESSAGE_PORT_ID		= 1,
	VMBUS_EVENT_CONNECTION_ID	= 2,
	VMBUS_EVENT_PORT_ID		= 2,
	VMBUS_MONITOR_CONNECTION_ID	= 3,
	VMBUS_MONITOR_PORT_ID		= 3,
	VMBUS_MESSAGE_SINT		= 2,
};

/*
 * Per cpu state for channel handling
 */
struct hv_per_cpu_context {
	void *synic_message_page;
	void *synic_event_page;
	/*
	 * buffer to post messages to the host.
	 */
	void *post_msg_page;

	/*
	 * Starting with win8, we can take channel interrupts on any CPU;
	 * we will manage the tasklet that handles events messages on a per CPU
	 * basis.
	 */
	struct tasklet_struct msg_dpc;
};

struct hv_context {
	/* We only support running on top of Hyper-V
	 * So at this point this really can only contain the Hyper-V ID
	 */
	u64 guestid;

	struct hv_per_cpu_context __percpu *cpu_context;

	/*
	 * To manage allocations in a NUMA node.
	 * Array indexed by numa node ID.
	 */
	struct cpumask *hv_numa_map;
};

extern struct hv_context hv_context;

/* Hv Interface */

extern int hv_init(void);

extern int hv_post_message(union hv_connection_id connection_id,
			 enum hv_message_type message_type,
			 void *payload, size_t payload_size);

extern int hv_synic_alloc(void);

extern void hv_synic_free(void);

extern void hv_synic_enable_regs(unsigned int cpu);
extern int hv_synic_init(unsigned int cpu);

extern void hv_synic_disable_regs(unsigned int cpu);
extern int hv_synic_cleanup(unsigned int cpu);

/* Interface */

void hv_ringbuffer_pre_init(struct vmbus_channel *channel);

int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
		       struct page *pages, u32 pagecnt);

void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);

int hv_ringbuffer_write(struct vmbus_channel *channel,
			const struct kvec *kv_list, u32 kv_count);

int hv_ringbuffer_read(struct vmbus_channel *channel,
		       void *buffer, u32 buflen, u32 *buffer_actual_len,
		       u64 *requestid, bool raw);

/*
 * The Maximum number of channels (16348) is determined by the size of the
 * interrupt page, which is HV_HYP_PAGE_SIZE. 1/2 of HV_HYP_PAGE_SIZE is to
 * send endpoint interrupts, and the other is to receive endpoint interrupts.
 */
#define MAX_NUM_CHANNELS	((HV_HYP_PAGE_SIZE >> 1) << 3)

/* The value here must be in multiple of 32 */
/* TODO: Need to make this configurable */
#define MAX_NUM_CHANNELS_SUPPORTED	256

#define MAX_CHANNEL_RELIDS					\
	max(MAX_NUM_CHANNELS_SUPPORTED, HV_EVENT_FLAGS_COUNT)

enum vmbus_connect_state {
	DISCONNECTED,
	CONNECTING,
	CONNECTED,
	DISCONNECTING
};

#define MAX_SIZE_CHANNEL_MESSAGE	HV_MESSAGE_PAYLOAD_BYTE_COUNT

/*
 * The CPU that Hyper-V will interrupt for VMBUS messages, such as
 * CHANNELMSG_OFFERCHANNEL and CHANNELMSG_RESCIND_CHANNELOFFER.
 */
#define VMBUS_CONNECT_CPU	0

struct vmbus_connection {
	u32 msg_conn_id;

	atomic_t offer_in_progress;

	enum vmbus_connect_state conn_state;

	atomic_t next_gpadl_handle;

	struct completion  unload_event;
	/*
	 * Represents channel interrupts. Each bit position represents a
	 * channel.  When a channel sends an interrupt via VMBUS, it finds its
	 * bit in the sendInterruptPage, set it and calls Hv to generate a port
	 * event. The other end receives the port event and parse the
	 * recvInterruptPage to see which bit is set
	 */
	void *int_page;
	void *send_int_page;
	void *recv_int_page;

	/*
	 * 2 pages - 1st page for parent->child notification and 2nd
	 * is child->parent notification
	 */
	struct hv_monitor_page *monitor_pages[2];
	struct list_head chn_msg_list;
	spinlock_t channelmsg_lock;

	/* List of channels */
	struct list_head chn_list;
	struct mutex channel_mutex;

	/* Array of channels */
	struct vmbus_channel **channels;

	/*
	 * An offer message is handled first on the work_queue, and then
	 * is further handled on handle_primary_chan_wq or
	 * handle_sub_chan_wq.
	 */
	struct workqueue_struct *work_queue;
	struct workqueue_struct *handle_primary_chan_wq;
	struct workqueue_struct *handle_sub_chan_wq;

	/*
	 * The number of sub-channels and hv_sock channels that should be
	 * cleaned up upon suspend: sub-channels will be re-created upon
	 * resume, and hv_sock channels should not survive suspend.
	 */
	atomic_t nr_chan_close_on_suspend;
	/*
	 * vmbus_bus_suspend() waits for "nr_chan_close_on_suspend" to
	 * drop to zero.
	 */
	struct completion ready_for_suspend_event;

	/*
	 * The number of primary channels that should be "fixed up"
	 * upon resume: these channels are re-offered upon resume, and some
	 * fields of the channel offers (i.e. child_relid and connection_id)
	 * can change, so the old offermsg must be fixed up, before the resume
	 * callbacks of the VSC drivers start to further touch the channels.
	 */
	atomic_t nr_chan_fixup_on_resume;
	/*
	 * vmbus_bus_resume() waits for "nr_chan_fixup_on_resume" to
	 * drop to zero.
	 */
	struct completion ready_for_resume_event;
};


struct vmbus_msginfo {
	/* Bookkeeping stuff */
	struct list_head msglist_entry;

	/* The message itself */
	unsigned char msg[];
};


extern struct vmbus_connection vmbus_connection;

int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version);

static inline void vmbus_send_interrupt(u32 relid)
{
	sync_set_bit(relid, vmbus_connection.send_int_page);
}

enum vmbus_message_handler_type {
	/* The related handler can sleep. */
	VMHT_BLOCKING = 0,

	/* The related handler must NOT sleep. */
	VMHT_NON_BLOCKING = 1,
};

struct vmbus_channel_message_table_entry {
	enum vmbus_channel_message_type message_type;
	enum vmbus_message_handler_type handler_type;
	void (*message_handler)(struct vmbus_channel_message_header *msg);
	u32 min_payload_len;
};

extern const struct vmbus_channel_message_table_entry
	channel_message_table[CHANNELMSG_COUNT];


/* General vmbus interface */

struct hv_device *vmbus_device_create(const guid_t *type,
				      const guid_t *instance,
				      struct vmbus_channel *channel);

int vmbus_device_register(struct hv_device *child_device_obj);
void vmbus_device_unregister(struct hv_device *device_obj);
int vmbus_add_channel_kobj(struct hv_device *device_obj,
			   struct vmbus_channel *channel);

void vmbus_remove_channel_attr_group(struct vmbus_channel *channel);

void vmbus_channel_map_relid(struct vmbus_channel *channel);
void vmbus_channel_unmap_relid(struct vmbus_channel *channel);

struct vmbus_channel *relid2channel(u32 relid);

void vmbus_free_channels(void);

/* Connection interface */

int vmbus_connect(void);
void vmbus_disconnect(void);

int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep);

void vmbus_on_event(unsigned long data);
void vmbus_on_msg_dpc(unsigned long data);

int hv_kvp_init(struct hv_util_service *srv);
void hv_kvp_deinit(void);
int hv_kvp_pre_suspend(void);
int hv_kvp_pre_resume(void);
void hv_kvp_onchannelcallback(void *context);

int hv_vss_init(struct hv_util_service *srv);
void hv_vss_deinit(void);
int hv_vss_pre_suspend(void);
int hv_vss_pre_resume(void);
void hv_vss_onchannelcallback(void *context);

int hv_fcopy_init(struct hv_util_service *srv);
void hv_fcopy_deinit(void);
int hv_fcopy_pre_suspend(void);
int hv_fcopy_pre_resume(void);
void hv_fcopy_onchannelcallback(void *context);
void vmbus_initiate_unload(bool crash);

static inline void hv_poll_channel(struct vmbus_channel *channel,
				   void (*cb)(void *))
{
	if (!channel