Pull block fixes from Jens Axboe:
- Several io_uring fixes/improvements:
- Blocking fix for O_DIRECT (me)
- Latter page slowness for registered buffers (me)
- Fix poll hang under certain conditions (me)
- Defer sequence check fix for wrapped rings (Zhengyuan)
- Mismatch in async inc/dec accounting (Zhengyuan)
- Memory ordering issue that could cause stall (Zhengyuan)
- Track sequential defer in bytes, not pages (Zhengyuan)
- NVMe pull request from Christoph
- Set of hang fixes for wbt (Josef)
- Redundant error message kill for libahci (Ding)
- Remove unused blk_mq_sched_started_request() and related ops (Marcos)
- drbd dynamic alloc shash descriptor to reduce stack use (Arnd)
- blkcg ->pd_stat() non-debug print (Tejun)
- bcache memory leak fix (Wei)
- Comment fix (Akinobu)
- BFQ perf regression fix (Paolo)
* tag 'for-linus-
20190726' of git://git.kernel.dk/linux-block: (24 commits)
io_uring: ensure ->list is initialized for poll commands
Revert "nvme-pci: don't create a read hctx mapping without read queues"
nvme: fix multipath crash when ANA is deactivated
nvme: fix memory leak caused by incorrect subsystem free
nvme: ignore subnqn for ADATA SX6000LNP
drbd: dynamically allocate shash descriptor
block: blk-mq: Remove blk_mq_sched_started_request and started_request
bcache: fix possible memory leak in bch_cached_dev_run()
io_uring: track io length in async_list based on bytes
io_uring: don't use iov_iter_advance() for fixed buffers
block: properly handle IOCB_NOWAIT for async O_DIRECT IO
blk-mq: allow REQ_NOWAIT to return an error inline
io_uring: add a memory barrier before atomic_read
rq-qos: use a mb for got_token
rq-qos: set ourself TASK_UNINTERRUPTIBLE after we schedule
rq-qos: don't reset has_sleepers on spurious wakeups
rq-qos: fix missed wake-ups in rq_qos_throttle
wait: add wq_has_single_sleeper helper
block, bfq: check also in-flight I/O in dispatch plugging
block: fix sysfs module parameters directory path in comment
...
* there is no active group, then the primary expectation for
* this device is probably a high throughput.
*
- * We are now left only with explaining the additional
- * compound condition that is checked below for deciding
- * whether the scenario is asymmetric. To explain this
- * compound condition, we need to add that the function
+ * We are now left only with explaining the two sub-conditions in the
+ * additional compound condition that is checked below for deciding
+ * whether the scenario is asymmetric. To explain the first
+ * sub-condition, we need to add that the function
* bfq_asymmetric_scenario checks the weights of only
- * non-weight-raised queues, for efficiency reasons (see
- * comments on bfq_weights_tree_add()). Then the fact that
- * bfqq is weight-raised is checked explicitly here. More
- * precisely, the compound condition below takes into account
- * also the fact that, even if bfqq is being weight-raised,
- * the scenario is still symmetric if all queues with requests
- * waiting for completion happen to be
- * weight-raised. Actually, we should be even more precise
- * here, and differentiate between interactive weight raising
- * and soft real-time weight raising.
+ * non-weight-raised queues, for efficiency reasons (see comments on
+ * bfq_weights_tree_add()). Then the fact that bfqq is weight-raised
+ * is checked explicitly here. More precisely, the compound condition
+ * below takes into account also the fact that, even if bfqq is being
+ * weight-raised, the scenario is still symmetric if all queues with
+ * requests waiting for completion happen to be
+ * weight-raised. Actually, we should be even more precise here, and
+ * differentiate between interactive weight raising and soft real-time
+ * weight raising.
+ *
+ * The second sub-condition checked in the compound condition is
+ * whether there is a fair amount of already in-flight I/O not
+ * belonging to bfqq. If so, I/O dispatching is to be plugged, for the
+ * following reason. The drive may decide to serve in-flight
+ * non-bfqq's I/O requests before bfqq's ones, thereby delaying the
+ * arrival of new I/O requests for bfqq (recall that bfqq is sync). If
+ * I/O-dispatching is not plugged, then, while bfqq remains empty, a
+ * basically uncontrolled amount of I/O from other queues may be
+ * dispatched too, possibly causing the service of bfqq's I/O to be
+ * delayed even longer in the drive. This problem gets more and more
+ * serious as the speed and the queue depth of the drive grow,
+ * because, as these two quantities grow, the probability to find no
+ * queue busy but many requests in flight grows too. By contrast,
+ * plugging I/O dispatching minimizes the delay induced by already
+ * in-flight I/O, and enables bfqq to recover the bandwidth it may
+ * lose because of this delay.
*
* As a side note, it is worth considering that the above
- * device-idling countermeasures may however fail in the
- * following unlucky scenario: if idling is (correctly)
- * disabled in a time period during which all symmetry
- * sub-conditions hold, and hence the device is allowed to
- * enqueue many requests, but at some later point in time some
- * sub-condition stops to hold, then it may become impossible
- * to let requests be served in the desired order until all
- * the requests already queued in the device have been served.
+ * device-idling countermeasures may however fail in the following
+ * unlucky scenario: if I/O-dispatch plugging is (correctly) disabled
+ * in a time period during which all symmetry sub-conditions hold, and
+ * therefore the device is allowed to enqueue many requests, but at
+ * some later point in time some sub-condition stops to hold, then it
+ * may become impossible to make requests be served in the desired
+ * order until all the requests already queued in the device have been
+ * served. The last sub-condition commented above somewhat mitigates
+ * this problem for weight-raised queues.
*/
static bool idling_needed_for_service_guarantees(struct bfq_data *bfqd,
struct bfq_queue *bfqq)
{
return (bfqq->wr_coeff > 1 &&
- bfqd->wr_busy_queues <
- bfq_tot_busy_queues(bfqd)) ||
+ (bfqd->wr_busy_queues <
+ bfq_tot_busy_queues(bfqd) ||
+ bfqd->rq_in_driver >=
+ bfqq->dispatched + 4)) ||
bfq_asymmetric_scenario(bfqd, bfqq);
}
static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
-static bool blkcg_debug_stats = false;
+bool blkcg_debug_stats = false;
static struct workqueue_struct *blkcg_punt_bio_wq;
static bool blkcg_policy_enabled(struct request_queue *q,
dbytes, dios);
}
- if (!blkcg_debug_stats)
- goto next;
-
- if (atomic_read(&blkg->use_delay)) {
+ if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) {
has_stats = true;
off += scnprintf(buf+off, size-off,
" use_delay=%d delay_nsec=%llu",
has_stats = true;
off += written;
}
-next:
+
if (has_stats) {
if (off < size - 1) {
off += scnprintf(buf+off, size-off, "\n");
unsigned long long avg_lat;
unsigned long long cur_win;
+ if (!blkcg_debug_stats)
+ return 0;
+
if (iolat->ssd)
return iolatency_ssd_stat(iolat, buf, size);
e->type->ops.completed_request(rq, now);
}
-static inline void blk_mq_sched_started_request(struct request *rq)
-{
- struct request_queue *q = rq->q;
- struct elevator_queue *e = q->elevator;
-
- if (e && e->type->ops.started_request)
- e->type->ops.started_request(rq);
-}
-
static inline void blk_mq_sched_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
{
struct request_queue *q = rq->q;
- blk_mq_sched_started_request(rq);
-
trace_block_rq_issue(q, rq);
if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
rq = blk_mq_get_request(q, bio, &data);
if (unlikely(!rq)) {
rq_qos_cleanup(q, bio);
- if (bio->bi_opf & REQ_NOWAIT)
+
+ cookie = BLK_QC_T_NONE;
+ if (bio->bi_opf & REQ_NOWAIT_INLINE)
+ cookie = BLK_QC_T_EAGAIN;
+ else if (bio->bi_opf & REQ_NOWAIT)
bio_wouldblock_error(bio);
- return BLK_QC_T_NONE;
+ return cookie;
}
trace_block_getrq(q, bio, bio->bi_opf);
return -1;
data->got_token = true;
+ smp_wmb();
list_del_init(&curr->entry);
wake_up_process(data->task);
return 1;
return;
prepare_to_wait_exclusive(&rqw->wait, &data.wq, TASK_UNINTERRUPTIBLE);
+ has_sleeper = !wq_has_single_sleeper(&rqw->wait);
do {
+ /* The memory barrier in set_task_state saves us here. */
if (data.got_token)
break;
if (!has_sleeper && acquire_inflight_cb(rqw, private_data)) {
* which means we now have two. Put our local token
* and wake anyone else potentially waiting for one.
*/
+ smp_rmb();
if (data.got_token)
cleanup_cb(rqw, private_data);
break;
}
io_schedule();
- has_sleeper = false;
+ has_sleeper = true;
+ set_current_state(TASK_UNINTERRUPTIBLE);
} while (1);
finish_wait(&rqw->wait, &data.wq);
}
* The default polling interval can be specified by the kernel
* parameter block.events_dfl_poll_msecs which defaults to 0
* (disable). This can also be modified runtime by writing to
- * /sys/module/block/events_dfl_poll_msecs.
+ * /sys/module/block/parameters/events_dfl_poll_msecs.
*/
static int disk_events_set_dfl_poll_msecs(const char *val,
const struct kernel_param *kp)
hpriv->mmio = devm_ioremap_resource(dev,
platform_get_resource(pdev, IORESOURCE_MEM, 0));
if (IS_ERR(hpriv->mmio)) {
- dev_err(dev, "no mmio space\n");
rc = PTR_ERR(hpriv->mmio);
goto err_out;
}
unsigned int key_len;
char secret[SHARED_SECRET_MAX]; /* 64 byte */
unsigned int resp_size;
- SHASH_DESC_ON_STACK(desc, connection->cram_hmac_tfm);
+ struct shash_desc *desc;
struct packet_info pi;
struct net_conf *nc;
int err, rv;
memcpy(secret, nc->shared_secret, key_len);
rcu_read_unlock();
+ desc = kmalloc(sizeof(struct shash_desc) +
+ crypto_shash_descsize(connection->cram_hmac_tfm),
+ GFP_KERNEL);
+ if (!desc) {
+ rv = -1;
+ goto fail;
+ }
desc->tfm = connection->cram_hmac_tfm;
rv = crypto_shash_setkey(connection->cram_hmac_tfm, (u8 *)secret, key_len);
kfree(peers_ch);
kfree(response);
kfree(right_response);
- shash_desc_zero(desc);
+ if (desc) {
+ shash_desc_zero(desc);
+ kfree(desc);
+ }
return rv;
}
if (dc->io_disable) {
pr_err("I/O disabled on cached dev %s",
dc->backing_dev_name);
+ kfree(env[1]);
+ kfree(env[2]);
+ kfree(buf);
return -EIO;
}
memset(subsys->subnqn + off, 0, sizeof(subsys->subnqn) - off);
}
-static void __nvme_release_subsystem(struct nvme_subsystem *subsys)
+static void nvme_release_subsystem(struct device *dev)
{
+ struct nvme_subsystem *subsys =
+ container_of(dev, struct nvme_subsystem, dev);
+
ida_simple_remove(&nvme_subsystems_ida, subsys->instance);
kfree(subsys);
}
-static void nvme_release_subsystem(struct device *dev)
-{
- __nvme_release_subsystem(container_of(dev, struct nvme_subsystem, dev));
-}
-
static void nvme_destroy_subsystem(struct kref *ref)
{
struct nvme_subsystem *subsys =
mutex_lock(&nvme_subsystems_lock);
found = __nvme_find_get_subsystem(subsys->subnqn);
if (found) {
- __nvme_release_subsystem(subsys);
+ put_device(&subsys->dev);
subsys = found;
if (!nvme_validate_cntlid(subsys, ctrl, id)) {
MODULE_PARM_DESC(multipath,
"turn on native support for multiple controllers per subsystem");
-inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl)
-{
- return multipath && ctrl->subsys && (ctrl->subsys->cmic & (1 << 3));
-}
-
/*
* If multipathing is enabled we need to always use the subsystem instance
* number for numbering our devices to avoid conflicts between subsystems that
{
int error;
- if (!nvme_ctrl_use_ana(ctrl))
+ /* check if multipath is enabled and we have the capability */
+ if (!multipath || !ctrl->subsys || !(ctrl->subsys->cmic & (1 << 3)))
return 0;
ctrl->anacap = id->anacap;
extern const struct block_device_operations nvme_ns_head_ops;
#ifdef CONFIG_NVME_MULTIPATH
-bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl);
+static inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl)
+{
+ return ctrl->ana_log_buf != NULL;
+}
+
void nvme_set_disk_name(char *disk_name, struct nvme_ns *ns,
struct nvme_ctrl *ctrl, int *flags);
void nvme_failover_req(struct request *req);
if (!dev->ctrl.tagset) {
dev->tagset.ops = &nvme_mq_ops;
dev->tagset.nr_hw_queues = dev->online_queues - 1;
- dev->tagset.nr_maps = 1; /* default */
- if (dev->io_queues[HCTX_TYPE_READ])
- dev->tagset.nr_maps++;
+ dev->tagset.nr_maps = 2; /* default + read */
if (dev->io_queues[HCTX_TYPE_POLL])
dev->tagset.nr_maps++;
dev->tagset.timeout = NVME_IO_TIMEOUT;
.driver_data = NVME_QUIRK_LIGHTNVM, },
{ PCI_DEVICE(0x1d1d, 0x2601), /* CNEX Granby */
.driver_data = NVME_QUIRK_LIGHTNVM, },
+ { PCI_DEVICE(0x10ec, 0x5762), /* ADATA SX6000LNP */
+ .driver_data = NVME_QUIRK_IGNORE_DEV_SUBNQN, },
{ PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_EXPRESS, 0xffffff) },
{ PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2001) },
{ PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2003) },
struct bio *bio;
bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
bool is_read = (iov_iter_rw(iter) == READ), is_sync;
+ bool nowait = (iocb->ki_flags & IOCB_NOWAIT) != 0;
loff_t pos = iocb->ki_pos;
blk_qc_t qc = BLK_QC_T_NONE;
- int ret = 0;
+ gfp_t gfp;
+ ssize_t ret;
if ((pos | iov_iter_alignment(iter)) &
(bdev_logical_block_size(bdev) - 1))
return -EINVAL;
- bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool);
+ if (nowait)
+ gfp = GFP_NOWAIT;
+ else
+ gfp = GFP_KERNEL;
+
+ bio = bio_alloc_bioset(gfp, nr_pages, &blkdev_dio_pool);
+ if (!bio)
+ return -EAGAIN;
dio = container_of(bio, struct blkdev_dio, bio);
dio->is_sync = is_sync = is_sync_kiocb(iocb);
if (!is_poll)
blk_start_plug(&plug);
+ ret = 0;
for (;;) {
+ int err;
+
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = pos >> 9;
bio->bi_write_hint = iocb->ki_hint;
bio->bi_end_io = blkdev_bio_end_io;
bio->bi_ioprio = iocb->ki_ioprio;
- ret = bio_iov_iter_get_pages(bio, iter);
- if (unlikely(ret)) {
+ err = bio_iov_iter_get_pages(bio, iter);
+ if (unlikely(err)) {
+ if (!ret)
+ ret = err;
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
break;
task_io_account_write(bio->bi_iter.bi_size);
}
+ /*
+ * Tell underlying layer to not block for resource shortage.
+ * And if we would have blocked, return error inline instead
+ * of through the bio->bi_end_io() callback.
+ */
+ if (nowait)
+ bio->bi_opf |= (REQ_NOWAIT | REQ_NOWAIT_INLINE);
+
dio->size += bio->bi_iter.bi_size;
pos += bio->bi_iter.bi_size;
}
qc = submit_bio(bio);
+ if (qc == BLK_QC_T_EAGAIN) {
+ if (!ret)
+ ret = -EAGAIN;
+ goto error;
+ }
if (polled)
WRITE_ONCE(iocb->ki_cookie, qc);
atomic_inc(&dio->ref);
}
- submit_bio(bio);
- bio = bio_alloc(GFP_KERNEL, nr_pages);
+ qc = submit_bio(bio);
+ if (qc == BLK_QC_T_EAGAIN) {
+ if (!ret)
+ ret = -EAGAIN;
+ goto error;
+ }
+ ret += bio->bi_iter.bi_size;
+
+ bio = bio_alloc(gfp, nr_pages);
+ if (!bio) {
+ if (!ret)
+ ret = -EAGAIN;
+ goto error;
+ }
}
if (!is_poll)
}
__set_current_state(TASK_RUNNING);
+out:
if (!ret)
ret = blk_status_to_errno(dio->bio.bi_status);
- if (likely(!ret))
- ret = dio->size;
bio_put(&dio->bio);
return ret;
+error:
+ if (!is_poll)
+ blk_finish_plug(&plug);
+ goto out;
}
static ssize_t
struct file *file;
off_t io_end;
- size_t io_pages;
+ size_t io_len;
};
struct io_ring_ctx {
#define REQ_F_IO_DRAIN 16 /* drain existing IO first */
#define REQ_F_IO_DRAINED 32 /* drain done */
#define REQ_F_LINK 64 /* linked sqes */
-#define REQ_F_FAIL_LINK 128 /* fail rest of links */
+#define REQ_F_LINK_DONE 128 /* linked sqes done */
+#define REQ_F_FAIL_LINK 256 /* fail rest of links */
u64 user_data;
u32 result;
u32 sequence;
if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
return false;
- return req->sequence > ctx->cached_cq_tail + ctx->sq_ring->dropped;
+ return req->sequence != ctx->cached_cq_tail + ctx->sq_ring->dropped;
}
static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
nxt->flags |= REQ_F_LINK;
}
+ nxt->flags |= REQ_F_LINK_DONE;
INIT_WORK(&nxt->work, io_sq_wq_submit_work);
queue_work(req->ctx->sqo_wq, &nxt->work);
}
*/
offset = buf_addr - imu->ubuf;
iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
- if (offset)
- iov_iter_advance(iter, offset);
+
+ if (offset) {
+ /*
+ * Don't use iov_iter_advance() here, as it's really slow for
+ * using the latter parts of a big fixed buffer - it iterates
+ * over each segment manually. We can cheat a bit here, because
+ * we know that:
+ *
+ * 1) it's a BVEC iter, we set it up
+ * 2) all bvecs are PAGE_SIZE in size, except potentially the
+ * first and last bvec
+ *
+ * So just find our index, and adjust the iterator afterwards.
+ * If the offset is within the first bvec (or the whole first
+ * bvec, just use iov_iter_advance(). This makes it easier
+ * since we can just skip the first segment, which may not
+ * be PAGE_SIZE aligned.
+ */
+ const struct bio_vec *bvec = imu->bvec;
+
+ if (offset <= bvec->bv_len) {
+ iov_iter_advance(iter, offset);
+ } else {
+ unsigned long seg_skip;
+
+ /* skip first vec */
+ offset -= bvec->bv_len;
+ seg_skip = 1 + (offset >> PAGE_SHIFT);
+
+ iter->bvec = bvec + seg_skip;
+ iter->nr_segs -= seg_skip;
+ iter->count -= (seg_skip << PAGE_SHIFT);
+ iter->iov_offset = offset & ~PAGE_MASK;
+ if (iter->iov_offset)
+ iter->count -= iter->iov_offset;
+ }
+ }
+
return 0;
}
off_t io_end = kiocb->ki_pos + len;
if (filp == async_list->file && kiocb->ki_pos == async_list->io_end) {
- unsigned long max_pages;
+ unsigned long max_bytes;
/* Use 8x RA size as a decent limiter for both reads/writes */
- max_pages = filp->f_ra.ra_pages;
- if (!max_pages)
- max_pages = VM_READAHEAD_PAGES;
- max_pages *= 8;
-
- /* If max pages are exceeded, reset the state */
- len >>= PAGE_SHIFT;
- if (async_list->io_pages + len <= max_pages) {
+ max_bytes = filp->f_ra.ra_pages << (PAGE_SHIFT + 3);
+ if (!max_bytes)
+ max_bytes = VM_READAHEAD_PAGES << (PAGE_SHIFT + 3);
+
+ /* If max len are exceeded, reset the state */
+ if (async_list->io_len + len <= max_bytes) {
req->flags |= REQ_F_SEQ_PREV;
- async_list->io_pages += len;
+ async_list->io_len += len;
} else {
io_end = 0;
- async_list->io_pages = 0;
+ async_list->io_len = 0;
}
}
/* New file? Reset state. */
if (async_list->file != filp) {
- async_list->io_pages = 0;
+ async_list->io_len = 0;
async_list->file = filp;
}
async_list->io_end = io_end;
INIT_LIST_HEAD(&poll->wait.entry);
init_waitqueue_func_entry(&poll->wait, io_poll_wake);
+ INIT_LIST_HEAD(&req->list);
+
mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
spin_lock_irq(&ctx->completion_lock);
/* async context always use a copy of the sqe */
kfree(sqe);
+ /* req from defer and link list needn't decrease async cnt */
+ if (req->flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE))
+ goto out;
+
if (!async_list)
break;
if (!list_empty(&req_list)) {
}
}
+out:
if (cur_mm) {
set_fs(old_fs);
unuse_mm(cur_mm);
ret = true;
spin_lock(&list->lock);
list_add_tail(&req->list, &list->list);
+ /*
+ * Ensure we see a simultaneous modification from io_sq_wq_submit_work()
+ */
+ smp_mb();
if (!atomic_read(&list->cnt)) {
list_del_init(&req->list);
ret = false;
extern struct blkcg blkcg_root;
extern struct cgroup_subsys_state * const blkcg_root_css;
+extern bool blkcg_debug_stats;
struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
struct request_queue *q, bool update_hint);
__REQ_RAHEAD, /* read ahead, can fail anytime */
__REQ_BACKGROUND, /* background IO */
__REQ_NOWAIT, /* Don't wait if request will block */
+ __REQ_NOWAIT_INLINE, /* Return would-block error inline */
/*
* When a shared kthread needs to issue a bio for a cgroup, doing
* so synchronously can lead to priority inversions as the kthread
#define REQ_RAHEAD (1ULL << __REQ_RAHEAD)
#define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND)
#define REQ_NOWAIT (1ULL << __REQ_NOWAIT)
+#define REQ_NOWAIT_INLINE (1ULL << __REQ_NOWAIT_INLINE)
#define REQ_CGROUP_PUNT (1ULL << __REQ_CGROUP_PUNT)
#define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP)
typedef unsigned int blk_qc_t;
#define BLK_QC_T_NONE -1U
+#define BLK_QC_T_EAGAIN -2U
#define BLK_QC_T_SHIFT 16
#define BLK_QC_T_INTERNAL (1U << 31)
static inline bool blk_qc_t_valid(blk_qc_t cookie)
{
- return cookie != BLK_QC_T_NONE;
+ return cookie != BLK_QC_T_NONE && cookie != BLK_QC_T_EAGAIN;
}
static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
bool (*has_work)(struct blk_mq_hw_ctx *);
void (*completed_request)(struct request *, u64);
- void (*started_request)(struct request *);
void (*requeue_request)(struct request *);
struct request *(*former_request)(struct request_queue *, struct request *);
struct request *(*next_request)(struct request_queue *, struct request *);
return !list_empty(&wq_head->head);
}
+/**
+ * wq_has_single_sleeper - check if there is only one sleeper
+ * @wq_head: wait queue head
+ *
+ * Returns true of wq_head has only one sleeper on the list.
+ *
+ * Please refer to the comment for waitqueue_active.
+ */
+static inline bool wq_has_single_sleeper(struct wait_queue_head *wq_head)
+{
+ return list_is_singular(&wq_head->head);
+}
+
/**
* wq_has_sleeper - check if there are any waiting processes
* @wq_head: wait queue head
projects / linux-2.6-block.git / commitdiff