android_kernel_xiaomi_sm7250/block/blk.h
Ming Lei fa137b50f3 block: split .sysfs_lock into two locks
commit cecf5d87ff2035127bb5a9ee054d0023a4a7cad3 upstream.

The kernfs built-in lock of 'kn->count' is held in sysfs .show/.store
path. Meantime, inside block's .show/.store callback, q->sysfs_lock is
required.

However, when mq & iosched kobjects are removed via
blk_mq_unregister_dev() & elv_unregister_queue(), q->sysfs_lock is held
too. This way causes AB-BA lock because the kernfs built-in lock of
'kn-count' is required inside kobject_del() too, see the lockdep warning[1].

On the other hand, it isn't necessary to acquire q->sysfs_lock for
both blk_mq_unregister_dev() & elv_unregister_queue() because
clearing REGISTERED flag prevents storing to 'queue/scheduler'
from being happened. Also sysfs write(store) is exclusive, so no
necessary to hold the lock for elv_unregister_queue() when it is
called in switching elevator path.

So split .sysfs_lock into two: one is still named as .sysfs_lock for
covering sync .store, the other one is named as .sysfs_dir_lock
for covering kobjects and related status change.

sysfs itself can handle the race between add/remove kobjects and
showing/storing attributes under kobjects. For switching scheduler
via storing to 'queue/scheduler', we use the queue flag of
QUEUE_FLAG_REGISTERED with .sysfs_lock for avoiding the race, then
we can avoid to hold .sysfs_lock during removing/adding kobjects.

[1]  lockdep warning
    ======================================================
    WARNING: possible circular locking dependency detected
    5.3.0-rc3-00044-g73277fc75ea0 #1380 Not tainted
    ------------------------------------------------------
    rmmod/777 is trying to acquire lock:
    00000000ac50e981 (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x59/0x72

    but task is already holding lock:
    00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #1 (&q->sysfs_lock){+.+.}:
           __lock_acquire+0x95f/0xa2f
           lock_acquire+0x1b4/0x1e8
           __mutex_lock+0x14a/0xa9b
           blk_mq_hw_sysfs_show+0x63/0xb6
           sysfs_kf_seq_show+0x11f/0x196
           seq_read+0x2cd/0x5f2
           vfs_read+0xc7/0x18c
           ksys_read+0xc4/0x13e
           do_syscall_64+0xa7/0x295
           entry_SYSCALL_64_after_hwframe+0x49/0xbe

    -> #0 (kn->count#202){++++}:
           check_prev_add+0x5d2/0xc45
           validate_chain+0xed3/0xf94
           __lock_acquire+0x95f/0xa2f
           lock_acquire+0x1b4/0x1e8
           __kernfs_remove+0x237/0x40b
           kernfs_remove_by_name_ns+0x59/0x72
           remove_files+0x61/0x96
           sysfs_remove_group+0x81/0xa4
           sysfs_remove_groups+0x3b/0x44
           kobject_del+0x44/0x94
           blk_mq_unregister_dev+0x83/0xdd
           blk_unregister_queue+0xa0/0x10b
           del_gendisk+0x259/0x3fa
           null_del_dev+0x8b/0x1c3 [null_blk]
           null_exit+0x5c/0x95 [null_blk]
           __se_sys_delete_module+0x204/0x337
           do_syscall_64+0xa7/0x295
           entry_SYSCALL_64_after_hwframe+0x49/0xbe

    other info that might help us debug this:

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(&q->sysfs_lock);
                                   lock(kn->count#202);
                                   lock(&q->sysfs_lock);
      lock(kn->count#202);

     *** DEADLOCK ***

    2 locks held by rmmod/777:
     #0: 00000000e69bd9de (&lock){+.+.}, at: null_exit+0x2e/0x95 [null_blk]
     #1: 00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b

    stack backtrace:
    CPU: 0 PID: 777 Comm: rmmod Not tainted 5.3.0-rc3-00044-g73277fc75ea0 #1380
    Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS ?-20180724_192412-buildhw-07.phx4
    Call Trace:
     dump_stack+0x9a/0xe6
     check_noncircular+0x207/0x251
     ? print_circular_bug+0x32a/0x32a
     ? find_usage_backwards+0x84/0xb0
     check_prev_add+0x5d2/0xc45
     validate_chain+0xed3/0xf94
     ? check_prev_add+0xc45/0xc45
     ? mark_lock+0x11b/0x804
     ? check_usage_forwards+0x1ca/0x1ca
     __lock_acquire+0x95f/0xa2f
     lock_acquire+0x1b4/0x1e8
     ? kernfs_remove_by_name_ns+0x59/0x72
     __kernfs_remove+0x237/0x40b
     ? kernfs_remove_by_name_ns+0x59/0x72
     ? kernfs_next_descendant_post+0x7d/0x7d
     ? strlen+0x10/0x23
     ? strcmp+0x22/0x44
     kernfs_remove_by_name_ns+0x59/0x72
     remove_files+0x61/0x96
     sysfs_remove_group+0x81/0xa4
     sysfs_remove_groups+0x3b/0x44
     kobject_del+0x44/0x94
     blk_mq_unregister_dev+0x83/0xdd
     blk_unregister_queue+0xa0/0x10b
     del_gendisk+0x259/0x3fa
     ? disk_events_poll_msecs_store+0x12b/0x12b
     ? check_flags+0x1ea/0x204
     ? mark_held_locks+0x1f/0x7a
     null_del_dev+0x8b/0x1c3 [null_blk]
     null_exit+0x5c/0x95 [null_blk]
     __se_sys_delete_module+0x204/0x337
     ? free_module+0x39f/0x39f
     ? blkcg_maybe_throttle_current+0x8a/0x718
     ? rwlock_bug+0x62/0x62
     ? __blkcg_punt_bio_submit+0xd0/0xd0
     ? trace_hardirqs_on_thunk+0x1a/0x20
     ? mark_held_locks+0x1f/0x7a
     ? do_syscall_64+0x4c/0x295
     do_syscall_64+0xa7/0x295
     entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x7fb696cdbe6b
    Code: 73 01 c3 48 8b 0d 1d 20 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 008
    RSP: 002b:00007ffec9588788 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
    RAX: ffffffffffffffda RBX: 0000559e589137c0 RCX: 00007fb696cdbe6b
    RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559e58913828
    RBP: 0000000000000000 R08: 00007ffec9587701 R09: 0000000000000000
    R10: 00007fb696d4eae0 R11: 0000000000000206 R12: 00007ffec95889b0
    R13: 00007ffec95896b3 R14: 0000559e58913260 R15: 0000559e589137c0

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(jwang:cherry picked from commit cecf5d87ff2035127bb5a9ee054d0023a4a7cad3,
adjust ctx for 4,19)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-04 09:39:30 +01:00

442 lines
13 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BLK_INTERNAL_H
#define BLK_INTERNAL_H
#include <linux/idr.h>
#include <linux/blk-mq.h>
#include "blk-mq.h"
/* Amount of time in which a process may batch requests */
#define BLK_BATCH_TIME (HZ/50UL)
/* Number of requests a "batching" process may submit */
#define BLK_BATCH_REQ 32
/* Max future timer expiry for timeouts */
#define BLK_MAX_TIMEOUT (5 * HZ)
#ifdef CONFIG_DEBUG_FS
extern struct dentry *blk_debugfs_root;
#endif
struct blk_flush_queue {
unsigned int flush_queue_delayed:1;
unsigned int flush_pending_idx:1;
unsigned int flush_running_idx:1;
blk_status_t rq_status;
unsigned long flush_pending_since;
struct list_head flush_queue[2];
struct list_head flush_data_in_flight;
struct request *flush_rq;
/*
* flush_rq shares tag with this rq, both can't be active
* at the same time
*/
struct request *orig_rq;
spinlock_t mq_flush_lock;
};
extern struct kmem_cache *blk_requestq_cachep;
extern struct kmem_cache *request_cachep;
extern struct kobj_type blk_queue_ktype;
extern struct ida blk_queue_ida;
/*
* @q->queue_lock is set while a queue is being initialized. Since we know
* that no other threads access the queue object before @q->queue_lock has
* been set, it is safe to manipulate queue flags without holding the
* queue_lock if @q->queue_lock == NULL. See also blk_alloc_queue_node() and
* blk_init_allocated_queue().
*/
static inline void queue_lockdep_assert_held(struct request_queue *q)
{
if (q->queue_lock)
lockdep_assert_held(q->queue_lock);
}
static inline void queue_flag_set_unlocked(unsigned int flag,
struct request_queue *q)
{
if (test_bit(QUEUE_FLAG_INIT_DONE, &q->queue_flags) &&
kref_read(&q->kobj.kref))
lockdep_assert_held(q->queue_lock);
__set_bit(flag, &q->queue_flags);
}
static inline void queue_flag_clear_unlocked(unsigned int flag,
struct request_queue *q)
{
if (test_bit(QUEUE_FLAG_INIT_DONE, &q->queue_flags) &&
kref_read(&q->kobj.kref))
lockdep_assert_held(q->queue_lock);
__clear_bit(flag, &q->queue_flags);
}
static inline int queue_flag_test_and_clear(unsigned int flag,
struct request_queue *q)
{
queue_lockdep_assert_held(q);
if (test_bit(flag, &q->queue_flags)) {
__clear_bit(flag, &q->queue_flags);
return 1;
}
return 0;
}
static inline int queue_flag_test_and_set(unsigned int flag,
struct request_queue *q)
{
queue_lockdep_assert_held(q);
if (!test_bit(flag, &q->queue_flags)) {
__set_bit(flag, &q->queue_flags);
return 0;
}
return 1;
}
static inline void queue_flag_set(unsigned int flag, struct request_queue *q)
{
queue_lockdep_assert_held(q);
__set_bit(flag, &q->queue_flags);
}
static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
{
queue_lockdep_assert_held(q);
__clear_bit(flag, &q->queue_flags);
}
static inline struct blk_flush_queue *blk_get_flush_queue(
struct request_queue *q, struct blk_mq_ctx *ctx)
{
if (q->mq_ops)
return blk_mq_map_queue(q, ctx->cpu)->fq;
return q->fq;
}
static inline void __blk_get_queue(struct request_queue *q)
{
kobject_get(&q->kobj);
}
static inline bool
is_flush_rq(struct request *req, struct blk_mq_hw_ctx *hctx)
{
return hctx->fq->flush_rq == req;
}
struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
int node, int cmd_size, gfp_t flags);
void blk_free_flush_queue(struct blk_flush_queue *q);
int blk_init_rl(struct request_list *rl, struct request_queue *q,
gfp_t gfp_mask);
void blk_exit_rl(struct request_queue *q, struct request_list *rl);
void blk_exit_queue(struct request_queue *q);
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio);
void blk_queue_bypass_start(struct request_queue *q);
void blk_queue_bypass_end(struct request_queue *q);
void __blk_queue_free_tags(struct request_queue *q);
void blk_freeze_queue(struct request_queue *q);
static inline void blk_queue_enter_live(struct request_queue *q)
{
/*
* Given that running in generic_make_request() context
* guarantees that a live reference against q_usage_counter has
* been established, further references under that same context
* need not check that the queue has been frozen (marked dead).
*/
percpu_ref_get(&q->q_usage_counter);
}
#ifdef CONFIG_BLK_DEV_INTEGRITY
void blk_flush_integrity(void);
bool __bio_integrity_endio(struct bio *);
static inline bool bio_integrity_endio(struct bio *bio)
{
if (bio_integrity(bio))
return __bio_integrity_endio(bio);
return true;
}
#else
static inline void blk_flush_integrity(void)
{
}
static inline bool bio_integrity_endio(struct bio *bio)
{
return true;
}
#endif
void blk_timeout_work(struct work_struct *work);
unsigned long blk_rq_timeout(unsigned long timeout);
void blk_add_timer(struct request *req);
void blk_delete_timer(struct request *);
bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
struct bio *bio);
bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
struct bio *bio);
bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
struct bio *bio);
bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
unsigned int *request_count,
struct request **same_queue_rq);
unsigned int blk_plug_queued_count(struct request_queue *q);
void blk_account_io_start(struct request *req, bool new_io);
void blk_account_io_completion(struct request *req, unsigned int bytes);
void blk_account_io_done(struct request *req, u64 now);
/*
* EH timer and IO completion will both attempt to 'grab' the request, make
* sure that only one of them succeeds. Steal the bottom bit of the
* __deadline field for this.
*/
static inline int blk_mark_rq_complete(struct request *rq)
{
return test_and_set_bit(0, &rq->__deadline);
}
static inline void blk_clear_rq_complete(struct request *rq)
{
clear_bit(0, &rq->__deadline);
}
static inline bool blk_rq_is_complete(struct request *rq)
{
return test_bit(0, &rq->__deadline);
}
/*
* Internal elevator interface
*/
#define ELV_ON_HASH(rq) ((rq)->rq_flags & RQF_HASHED)
void blk_insert_flush(struct request *rq);
static inline void elv_activate_rq(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;
if (e->type->ops.sq.elevator_activate_req_fn)
e->type->ops.sq.elevator_activate_req_fn(q, rq);
}
static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;
if (e->type->ops.sq.elevator_deactivate_req_fn)
e->type->ops.sq.elevator_deactivate_req_fn(q, rq);
}
int elevator_init(struct request_queue *);
int elevator_init_mq(struct request_queue *q);
int elevator_switch_mq(struct request_queue *q,
struct elevator_type *new_e);
void elevator_exit(struct request_queue *, struct elevator_queue *);
int elv_register_queue(struct request_queue *q, bool uevent);
void elv_unregister_queue(struct request_queue *q);
struct hd_struct *__disk_get_part(struct gendisk *disk, int partno);
#ifdef CONFIG_FAIL_IO_TIMEOUT
int blk_should_fake_timeout(struct request_queue *);
ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
ssize_t part_timeout_store(struct device *, struct device_attribute *,
const char *, size_t);
#else
static inline int blk_should_fake_timeout(struct request_queue *q)
{
return 0;
}
#endif
int ll_back_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio);
int ll_front_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio);
struct request *attempt_back_merge(struct request_queue *q, struct request *rq);
struct request *attempt_front_merge(struct request_queue *q, struct request *rq);
int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
struct request *next);
void blk_recalc_rq_segments(struct request *rq);
void blk_rq_set_mixed_merge(struct request *rq);
bool blk_rq_merge_ok(struct request *rq, struct bio *bio);
enum elv_merge blk_try_merge(struct request *rq, struct bio *bio);
void blk_queue_congestion_threshold(struct request_queue *q);
int blk_dev_init(void);
/*
* Return the threshold (number of used requests) at which the queue is
* considered to be congested. It include a little hysteresis to keep the
* context switch rate down.
*/
static inline int queue_congestion_on_threshold(struct request_queue *q)
{
return q->nr_congestion_on;
}
/*
* The threshold at which a queue is considered to be uncongested
*/
static inline int queue_congestion_off_threshold(struct request_queue *q)
{
return q->nr_congestion_off;
}
extern int blk_update_nr_requests(struct request_queue *, unsigned int);
/*
* Contribute to IO statistics IFF:
*
* a) it's attached to a gendisk, and
* b) the queue had IO stats enabled when this request was started, and
* c) it's a file system request
*/
static inline bool blk_do_io_stat(struct request *rq)
{
return rq->rq_disk &&
(rq->rq_flags & RQF_IO_STAT) &&
!blk_rq_is_passthrough(rq);
}
static inline void req_set_nomerge(struct request_queue *q, struct request *req)
{
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
q->last_merge = NULL;
}
/*
* Steal a bit from this field for legacy IO path atomic IO marking. Note that
* setting the deadline clears the bottom bit, potentially clearing the
* completed bit. The user has to be OK with this (current ones are fine).
*/
static inline void blk_rq_set_deadline(struct request *rq, unsigned long time)
{
rq->__deadline = time & ~0x1UL;
}
static inline unsigned long blk_rq_deadline(struct request *rq)
{
return rq->__deadline & ~0x1UL;
}
/*
* The max size one bio can handle is UINT_MAX becasue bvec_iter.bi_size
* is defined as 'unsigned int', meantime it has to aligned to with logical
* block size which is the minimum accepted unit by hardware.
*/
static inline unsigned int bio_allowed_max_sectors(struct request_queue *q)
{
return round_down(UINT_MAX, queue_logical_block_size(q)) >> 9;
}
/*
* Internal io_context interface
*/
void get_io_context(struct io_context *ioc);
struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q);
struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
gfp_t gfp_mask);
void ioc_clear_queue(struct request_queue *q);
int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node);
/**
* rq_ioc - determine io_context for request allocation
* @bio: request being allocated is for this bio (can be %NULL)
*
* Determine io_context to use for request allocation for @bio. May return
* %NULL if %current->io_context doesn't exist.
*/
static inline struct io_context *rq_ioc(struct bio *bio)
{
#ifdef CONFIG_BLK_CGROUP
if (bio && bio->bi_ioc)
return bio->bi_ioc;
#endif
return current->io_context;
}
/**
* create_io_context - try to create task->io_context
* @gfp_mask: allocation mask
* @node: allocation node
*
* If %current->io_context is %NULL, allocate a new io_context and install
* it. Returns the current %current->io_context which may be %NULL if
* allocation failed.
*
* Note that this function can't be called with IRQ disabled because
* task_lock which protects %current->io_context is IRQ-unsafe.
*/
static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
{
WARN_ON_ONCE(irqs_disabled());
if (unlikely(!current->io_context))
create_task_io_context(current, gfp_mask, node);
return current->io_context;
}
/*
* Internal throttling interface
*/
#ifdef CONFIG_BLK_DEV_THROTTLING
extern void blk_throtl_drain(struct request_queue *q);
extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
extern void blk_throtl_register_queue(struct request_queue *q);
#else /* CONFIG_BLK_DEV_THROTTLING */
static inline void blk_throtl_drain(struct request_queue *q) { }
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
static inline void blk_throtl_register_queue(struct request_queue *q) { }
#endif /* CONFIG_BLK_DEV_THROTTLING */
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
const char *page, size_t count);
extern void blk_throtl_bio_endio(struct bio *bio);
extern void blk_throtl_stat_add(struct request *rq, u64 time);
#else
static inline void blk_throtl_bio_endio(struct bio *bio) { }
static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
#endif
#ifdef CONFIG_BOUNCE
extern int init_emergency_isa_pool(void);
extern void blk_queue_bounce(struct request_queue *q, struct bio **bio);
#else
static inline int init_emergency_isa_pool(void)
{
return 0;
}
static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio)
{
}
#endif /* CONFIG_BOUNCE */
extern void blk_drain_queue(struct request_queue *q);
#ifdef CONFIG_BLK_CGROUP_IOLATENCY
extern int blk_iolatency_init(struct request_queue *q);
#else
static inline int blk_iolatency_init(struct request_queue *q) { return 0; }
#endif
#endif /* BLK_INTERNAL_H */