Move the task work handling code out of io_uring.c into a new tw.c file.
This includes the local work, normal work, and fallback work handling
infrastructure.
The associated tw.h header contains io_should_terminate_tw() as a static
inline helper, along with the necessary function declarations.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
obj-$(CONFIG_IO_URING) += io_uring.o opdef.o kbuf.o rsrc.o notif.o \
tctx.o filetable.o rw.o poll.o \
- eventfd.o uring_cmd.o openclose.o \
+ tw.o eventfd.o uring_cmd.o openclose.o \
sqpoll.o xattr.o nop.o fs.o splice.o \
sync.o msg_ring.o advise.o openclose.o \
statx.o timeout.o cancel.o \
waitid.o register.o truncate.o \
memmap.o alloc_cache.o query.o
+
obj-$(CONFIG_IO_URING_ZCRX) += zcrx.o
obj-$(CONFIG_IO_WQ) += io-wq.o
obj-$(CONFIG_FUTEX) += futex.o
#define IO_COMPL_BATCH 32
#define IO_REQ_ALLOC_BATCH 8
-#define IO_LOCAL_TW_DEFAULT_MAX 20
/* requests with any of those set should undergo io_disarm_next() */
#define IO_DISARM_MASK (REQ_F_ARM_LTIMEOUT | REQ_F_LINK_TIMEOUT | REQ_F_FAIL)
-/*
- * No waiters. It's larger than any valid value of the tw counter
- * so that tests against ->cq_wait_nr would fail and skip wake_up().
- */
-#define IO_CQ_WAKE_INIT (-1U)
-/* Forced wake up if there is a waiter regardless of ->cq_wait_nr */
-#define IO_CQ_WAKE_FORCE (IO_CQ_WAKE_INIT >> 1)
-
static void io_queue_sqe(struct io_kiocb *req, unsigned int extra_flags);
static void __io_req_caches_free(struct io_ring_ctx *ctx);
complete(&ctx->ref_comp);
}
-/*
- * Terminate the request if either of these conditions are true:
- *
- * 1) It's being executed by the original task, but that task is marked
- * with PF_EXITING as it's exiting.
- * 2) PF_KTHREAD is set, in which case the invoker of the task_work is
- * our fallback task_work.
- * 3) The ring has been closed and is going away.
- */
-static inline bool io_should_terminate_tw(struct io_ring_ctx *ctx)
-{
- return (current->flags & (PF_EXITING | PF_KTHREAD)) || percpu_ref_is_dying(&ctx->refs);
-}
-
-static __cold void io_fallback_req_func(struct work_struct *work)
-{
- struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx,
- fallback_work.work);
- struct llist_node *node = llist_del_all(&ctx->fallback_llist);
- struct io_kiocb *req, *tmp;
- struct io_tw_state ts = {};
-
- percpu_ref_get(&ctx->refs);
- mutex_lock(&ctx->uring_lock);
- ts.cancel = io_should_terminate_tw(ctx);
- llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
- req->io_task_work.func((struct io_tw_req){req}, ts);
- io_submit_flush_completions(ctx);
- mutex_unlock(&ctx->uring_lock);
- percpu_ref_put(&ctx->refs);
-}
-
static int io_alloc_hash_table(struct io_hash_table *table, unsigned bits)
{
unsigned int hash_buckets;
return nxt;
}
-static void ctx_flush_and_put(struct io_ring_ctx *ctx, io_tw_token_t tw)
-{
- if (!ctx)
- return;
- if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
- atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
-
- io_submit_flush_completions(ctx);
- mutex_unlock(&ctx->uring_lock);
- percpu_ref_put(&ctx->refs);
-}
-
-/*
- * Run queued task_work, returning the number of entries processed in *count.
- * If more entries than max_entries are available, stop processing once this
- * is reached and return the rest of the list.
- */
-struct llist_node *io_handle_tw_list(struct llist_node *node,
- unsigned int *count,
- unsigned int max_entries)
-{
- struct io_ring_ctx *ctx = NULL;
- struct io_tw_state ts = { };
-
- do {
- struct llist_node *next = node->next;
- struct io_kiocb *req = container_of(node, struct io_kiocb,
- io_task_work.node);
-
- if (req->ctx != ctx) {
- ctx_flush_and_put(ctx, ts);
- ctx = req->ctx;
- mutex_lock(&ctx->uring_lock);
- percpu_ref_get(&ctx->refs);
- ts.cancel = io_should_terminate_tw(ctx);
- }
- INDIRECT_CALL_2(req->io_task_work.func,
- io_poll_task_func, io_req_rw_complete,
- (struct io_tw_req){req}, ts);
- node = next;
- (*count)++;
- if (unlikely(need_resched())) {
- ctx_flush_and_put(ctx, ts);
- ctx = NULL;
- cond_resched();
- }
- } while (node && *count < max_entries);
-
- ctx_flush_and_put(ctx, ts);
- return node;
-}
-
-static __cold void __io_fallback_tw(struct llist_node *node, bool sync)
-{
- struct io_ring_ctx *last_ctx = NULL;
- struct io_kiocb *req;
-
- while (node) {
- req = container_of(node, struct io_kiocb, io_task_work.node);
- node = node->next;
- if (last_ctx != req->ctx) {
- if (last_ctx) {
- if (sync)
- flush_delayed_work(&last_ctx->fallback_work);
- percpu_ref_put(&last_ctx->refs);
- }
- last_ctx = req->ctx;
- percpu_ref_get(&last_ctx->refs);
- }
- if (llist_add(&req->io_task_work.node, &last_ctx->fallback_llist))
- schedule_delayed_work(&last_ctx->fallback_work, 1);
- }
-
- if (last_ctx) {
- if (sync)
- flush_delayed_work(&last_ctx->fallback_work);
- percpu_ref_put(&last_ctx->refs);
- }
-}
-
-static void io_fallback_tw(struct io_uring_task *tctx, bool sync)
-{
- struct llist_node *node = llist_del_all(&tctx->task_list);
-
- __io_fallback_tw(node, sync);
-}
-
-struct llist_node *tctx_task_work_run(struct io_uring_task *tctx,
- unsigned int max_entries,
- unsigned int *count)
-{
- struct llist_node *node;
-
- node = llist_del_all(&tctx->task_list);
- if (node) {
- node = llist_reverse_order(node);
- node = io_handle_tw_list(node, count, max_entries);
- }
-
- /* relaxed read is enough as only the task itself sets ->in_cancel */
- if (unlikely(atomic_read(&tctx->in_cancel)))
- io_uring_drop_tctx_refs(current);
-
- trace_io_uring_task_work_run(tctx, *count);
- return node;
-}
-
-void tctx_task_work(struct callback_head *cb)
-{
- struct io_uring_task *tctx;
- struct llist_node *ret;
- unsigned int count = 0;
-
- tctx = container_of(cb, struct io_uring_task, task_work);
- ret = tctx_task_work_run(tctx, UINT_MAX, &count);
- /* can't happen */
- WARN_ON_ONCE(ret);
-}
-
-static void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
-{
- struct io_ring_ctx *ctx = req->ctx;
- unsigned nr_wait, nr_tw, nr_tw_prev;
- struct llist_node *head;
-
- /* See comment above IO_CQ_WAKE_INIT */
- BUILD_BUG_ON(IO_CQ_WAKE_FORCE <= IORING_MAX_CQ_ENTRIES);
-
- /*
- * We don't know how many requests there are in the link and whether
- * they can even be queued lazily, fall back to non-lazy.
- */
- if (req->flags & IO_REQ_LINK_FLAGS)
- flags &= ~IOU_F_TWQ_LAZY_WAKE;
-
- guard(rcu)();
-
- head = READ_ONCE(ctx->work_llist.first);
- do {
- nr_tw_prev = 0;
- if (head) {
- struct io_kiocb *first_req = container_of(head,
- struct io_kiocb,
- io_task_work.node);
- /*
- * Might be executed at any moment, rely on
- * SLAB_TYPESAFE_BY_RCU to keep it alive.
- */
- nr_tw_prev = READ_ONCE(first_req->nr_tw);
- }
-
- /*
- * Theoretically, it can overflow, but that's fine as one of
- * previous adds should've tried to wake the task.
- */
- nr_tw = nr_tw_prev + 1;
- if (!(flags & IOU_F_TWQ_LAZY_WAKE))
- nr_tw = IO_CQ_WAKE_FORCE;
-
- req->nr_tw = nr_tw;
- req->io_task_work.node.next = head;
- } while (!try_cmpxchg(&ctx->work_llist.first, &head,
- &req->io_task_work.node));
-
- /*
- * cmpxchg implies a full barrier, which pairs with the barrier
- * in set_current_state() on the io_cqring_wait() side. It's used
- * to ensure that either we see updated ->cq_wait_nr, or waiters
- * going to sleep will observe the work added to the list, which
- * is similar to the wait/wawke task state sync.
- */
-
- if (!head) {
- if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
- atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
- if (ctx->has_evfd)
- io_eventfd_signal(ctx, false);
- }
-
- nr_wait = atomic_read(&ctx->cq_wait_nr);
- /* not enough or no one is waiting */
- if (nr_tw < nr_wait)
- return;
- /* the previous add has already woken it up */
- if (nr_tw_prev >= nr_wait)
- return;
- wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
-}
-
-static void io_req_normal_work_add(struct io_kiocb *req)
-{
- struct io_uring_task *tctx = req->tctx;
- struct io_ring_ctx *ctx = req->ctx;
-
- /* task_work already pending, we're done */
- if (!llist_add(&req->io_task_work.node, &tctx->task_list))
- return;
-
- if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
- atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
-
- /* SQPOLL doesn't need the task_work added, it'll run it itself */
- if (ctx->flags & IORING_SETUP_SQPOLL) {
- __set_notify_signal(tctx->task);
- return;
- }
-
- if (likely(!task_work_add(tctx->task, &tctx->task_work, ctx->notify_method)))
- return;
-
- io_fallback_tw(tctx, false);
-}
-
-void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
-{
- if (req->ctx->flags & IORING_SETUP_DEFER_TASKRUN)
- io_req_local_work_add(req, flags);
- else
- io_req_normal_work_add(req);
-}
-
-void io_req_task_work_add_remote(struct io_kiocb *req, unsigned flags)
-{
- if (WARN_ON_ONCE(!(req->ctx->flags & IORING_SETUP_DEFER_TASKRUN)))
- return;
- __io_req_task_work_add(req, flags);
-}
-
-static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
-{
- struct llist_node *node = llist_del_all(&ctx->work_llist);
-
- __io_fallback_tw(node, false);
- node = llist_del_all(&ctx->retry_llist);
- __io_fallback_tw(node, false);
-}
-
-static bool io_run_local_work_continue(struct io_ring_ctx *ctx, int events,
- int min_events)
-{
- if (!io_local_work_pending(ctx))
- return false;
- if (events < min_events)
- return true;
- if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
- atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
- return false;
-}
-
-static int __io_run_local_work_loop(struct llist_node **node,
- io_tw_token_t tw,
- int events)
-{
- int ret = 0;
-
- while (*node) {
- struct llist_node *next = (*node)->next;
- struct io_kiocb *req = container_of(*node, struct io_kiocb,
- io_task_work.node);
- INDIRECT_CALL_2(req->io_task_work.func,
- io_poll_task_func, io_req_rw_complete,
- (struct io_tw_req){req}, tw);
- *node = next;
- if (++ret >= events)
- break;
- }
-
- return ret;
-}
-
-static int __io_run_local_work(struct io_ring_ctx *ctx, io_tw_token_t tw,
- int min_events, int max_events)
-{
- struct llist_node *node;
- unsigned int loops = 0;
- int ret = 0;
-
- if (WARN_ON_ONCE(ctx->submitter_task != current))
- return -EEXIST;
- if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
- atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
-again:
- tw.cancel = io_should_terminate_tw(ctx);
- min_events -= ret;
- ret = __io_run_local_work_loop(&ctx->retry_llist.first, tw, max_events);
- if (ctx->retry_llist.first)
- goto retry_done;
-
- /*
- * llists are in reverse order, flip it back the right way before
- * running the pending items.
- */
- node = llist_reverse_order(llist_del_all(&ctx->work_llist));
- ret += __io_run_local_work_loop(&node, tw, max_events - ret);
- ctx->retry_llist.first = node;
- loops++;
-
- if (io_run_local_work_continue(ctx, ret, min_events))
- goto again;
-retry_done:
- io_submit_flush_completions(ctx);
- if (io_run_local_work_continue(ctx, ret, min_events))
- goto again;
-
- trace_io_uring_local_work_run(ctx, ret, loops);
- return ret;
-}
-
-static inline int io_run_local_work_locked(struct io_ring_ctx *ctx,
- int min_events)
-{
- struct io_tw_state ts = {};
-
- if (!io_local_work_pending(ctx))
- return 0;
- return __io_run_local_work(ctx, ts, min_events,
- max(IO_LOCAL_TW_DEFAULT_MAX, min_events));
-}
-
-int io_run_local_work(struct io_ring_ctx *ctx, int min_events, int max_events)
-{
- struct io_tw_state ts = {};
- int ret;
-
- mutex_lock(&ctx->uring_lock);
- ret = __io_run_local_work(ctx, ts, min_events, max_events);
- mutex_unlock(&ctx->uring_lock);
- return ret;
-}
-
static void io_req_task_cancel(struct io_tw_req tw_req, io_tw_token_t tw)
{
struct io_kiocb *req = tw_req.req;
#include "alloc_cache.h"
#include "io-wq.h"
#include "slist.h"
+#include "tw.h"
#include "opdef.h"
#ifndef CREATE_TRACE_POINTS
IOSQE_BUFFER_SELECT |\
IOSQE_CQE_SKIP_SUCCESS)
+#define IO_REQ_LINK_FLAGS (REQ_F_LINK | REQ_F_HARDLINK)
+
/*
* Complaint timeout for io_uring cancelation exits, and for io-wq exit
* worker waiting.
int io_prepare_config(struct io_ctx_config *config);
bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow, bool cqe32);
-int io_run_task_work_sig(struct io_ring_ctx *ctx);
-int io_run_local_work(struct io_ring_ctx *ctx, int min_events, int max_events);
void io_req_defer_failed(struct io_kiocb *req, s32 res);
bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags);
void io_add_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags);
struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned issue_flags);
-void __io_req_task_work_add(struct io_kiocb *req, unsigned flags);
-void io_req_task_work_add_remote(struct io_kiocb *req, unsigned flags);
void io_req_task_queue(struct io_kiocb *req);
void io_req_task_complete(struct io_tw_req tw_req, io_tw_token_t tw);
void io_req_task_queue_fail(struct io_kiocb *req, int ret);
void io_req_task_submit(struct io_tw_req tw_req, io_tw_token_t tw);
-struct llist_node *io_handle_tw_list(struct llist_node *node, unsigned int *count, unsigned int max_entries);
-struct llist_node *tctx_task_work_run(struct io_uring_task *tctx, unsigned int max_entries, unsigned int *count);
-void tctx_task_work(struct callback_head *cb);
__cold void io_uring_drop_tctx_refs(struct task_struct *task);
int io_ring_add_registered_file(struct io_uring_task *tctx, struct file *file,
return IS_ENABLED(CONFIG_COMPAT) && unlikely(ctx->compat);
}
-static inline void io_req_task_work_add(struct io_kiocb *req)
-{
- __io_req_task_work_add(req, 0);
-}
-
static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
{
if (!wq_list_empty(&ctx->submit_state.compl_reqs) ||
return min(entries, ctx->sq_entries);
}
-static inline int io_run_task_work(void)
-{
- bool ret = false;
-
- /*
- * Always check-and-clear the task_work notification signal. With how
- * signaling works for task_work, we can find it set with nothing to
- * run. We need to clear it for that case, like get_signal() does.
- */
- if (test_thread_flag(TIF_NOTIFY_SIGNAL))
- clear_notify_signal();
- /*
- * PF_IO_WORKER never returns to userspace, so check here if we have
- * notify work that needs processing.
- */
- if (current->flags & PF_IO_WORKER) {
- if (test_thread_flag(TIF_NOTIFY_RESUME)) {
- __set_current_state(TASK_RUNNING);
- resume_user_mode_work(NULL);
- }
- if (current->io_uring) {
- unsigned int count = 0;
-
- __set_current_state(TASK_RUNNING);
- tctx_task_work_run(current->io_uring, UINT_MAX, &count);
- if (count)
- ret = true;
- }
- }
- if (task_work_pending(current)) {
- __set_current_state(TASK_RUNNING);
- task_work_run();
- ret = true;
- }
-
- return ret;
-}
-
-static inline bool io_local_work_pending(struct io_ring_ctx *ctx)
-{
- return !llist_empty(&ctx->work_llist) || !llist_empty(&ctx->retry_llist);
-}
-
-static inline bool io_task_work_pending(struct io_ring_ctx *ctx)
-{
- return task_work_pending(current) || io_local_work_pending(ctx);
-}
-
-static inline void io_tw_lock(struct io_ring_ctx *ctx, io_tw_token_t tw)
-{
- lockdep_assert_held(&ctx->uring_lock);
-}
-
/*
* Don't complete immediately but use deferred completion infrastructure.
* Protected by ->uring_lock and can only be used either with
return true;
}
-static inline bool io_allowed_defer_tw_run(struct io_ring_ctx *ctx)
-{
- return likely(ctx->submitter_task == current);
-}
-
-static inline bool io_allowed_run_tw(struct io_ring_ctx *ctx)
-{
- return likely(!(ctx->flags & IORING_SETUP_DEFER_TASKRUN) ||
- ctx->submitter_task == current);
-}
-
static inline void io_req_queue_tw_complete(struct io_kiocb *req, s32 res)
{
io_req_set_res(req, res, 0);
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Task work handling for io_uring
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/sched/signal.h>
+#include <linux/io_uring.h>
+#include <linux/indirect_call_wrapper.h>
+
+#include "io_uring.h"
+#include "tctx.h"
+#include "poll.h"
+#include "rw.h"
+#include "eventfd.h"
+
+void io_fallback_req_func(struct work_struct *work)
+{
+ struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx,
+ fallback_work.work);
+ struct llist_node *node = llist_del_all(&ctx->fallback_llist);
+ struct io_kiocb *req, *tmp;
+ struct io_tw_state ts = {};
+
+ percpu_ref_get(&ctx->refs);
+ mutex_lock(&ctx->uring_lock);
+ ts.cancel = io_should_terminate_tw(ctx);
+ llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
+ req->io_task_work.func((struct io_tw_req){req}, ts);
+ io_submit_flush_completions(ctx);
+ mutex_unlock(&ctx->uring_lock);
+ percpu_ref_put(&ctx->refs);
+}
+
+static void ctx_flush_and_put(struct io_ring_ctx *ctx, io_tw_token_t tw)
+{
+ if (!ctx)
+ return;
+ if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+ atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+
+ io_submit_flush_completions(ctx);
+ mutex_unlock(&ctx->uring_lock);
+ percpu_ref_put(&ctx->refs);
+}
+
+/*
+ * Run queued task_work, returning the number of entries processed in *count.
+ * If more entries than max_entries are available, stop processing once this
+ * is reached and return the rest of the list.
+ */
+struct llist_node *io_handle_tw_list(struct llist_node *node,
+ unsigned int *count,
+ unsigned int max_entries)
+{
+ struct io_ring_ctx *ctx = NULL;
+ struct io_tw_state ts = { };
+
+ do {
+ struct llist_node *next = node->next;
+ struct io_kiocb *req = container_of(node, struct io_kiocb,
+ io_task_work.node);
+
+ if (req->ctx != ctx) {
+ ctx_flush_and_put(ctx, ts);
+ ctx = req->ctx;
+ mutex_lock(&ctx->uring_lock);
+ percpu_ref_get(&ctx->refs);
+ ts.cancel = io_should_terminate_tw(ctx);
+ }
+ INDIRECT_CALL_2(req->io_task_work.func,
+ io_poll_task_func, io_req_rw_complete,
+ (struct io_tw_req){req}, ts);
+ node = next;
+ (*count)++;
+ if (unlikely(need_resched())) {
+ ctx_flush_and_put(ctx, ts);
+ ctx = NULL;
+ cond_resched();
+ }
+ } while (node && *count < max_entries);
+
+ ctx_flush_and_put(ctx, ts);
+ return node;
+}
+
+static __cold void __io_fallback_tw(struct llist_node *node, bool sync)
+{
+ struct io_ring_ctx *last_ctx = NULL;
+ struct io_kiocb *req;
+
+ while (node) {
+ req = container_of(node, struct io_kiocb, io_task_work.node);
+ node = node->next;
+ if (last_ctx != req->ctx) {
+ if (last_ctx) {
+ if (sync)
+ flush_delayed_work(&last_ctx->fallback_work);
+ percpu_ref_put(&last_ctx->refs);
+ }
+ last_ctx = req->ctx;
+ percpu_ref_get(&last_ctx->refs);
+ }
+ if (llist_add(&req->io_task_work.node, &last_ctx->fallback_llist))
+ schedule_delayed_work(&last_ctx->fallback_work, 1);
+ }
+
+ if (last_ctx) {
+ if (sync)
+ flush_delayed_work(&last_ctx->fallback_work);
+ percpu_ref_put(&last_ctx->refs);
+ }
+}
+
+static void io_fallback_tw(struct io_uring_task *tctx, bool sync)
+{
+ struct llist_node *node = llist_del_all(&tctx->task_list);
+
+ __io_fallback_tw(node, sync);
+}
+
+struct llist_node *tctx_task_work_run(struct io_uring_task *tctx,
+ unsigned int max_entries,
+ unsigned int *count)
+{
+ struct llist_node *node;
+
+ node = llist_del_all(&tctx->task_list);
+ if (node) {
+ node = llist_reverse_order(node);
+ node = io_handle_tw_list(node, count, max_entries);
+ }
+
+ /* relaxed read is enough as only the task itself sets ->in_cancel */
+ if (unlikely(atomic_read(&tctx->in_cancel)))
+ io_uring_drop_tctx_refs(current);
+
+ trace_io_uring_task_work_run(tctx, *count);
+ return node;
+}
+
+void tctx_task_work(struct callback_head *cb)
+{
+ struct io_uring_task *tctx;
+ struct llist_node *ret;
+ unsigned int count = 0;
+
+ tctx = container_of(cb, struct io_uring_task, task_work);
+ ret = tctx_task_work_run(tctx, UINT_MAX, &count);
+ /* can't happen */
+ WARN_ON_ONCE(ret);
+}
+
+void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ unsigned nr_wait, nr_tw, nr_tw_prev;
+ struct llist_node *head;
+
+ /* See comment above IO_CQ_WAKE_INIT */
+ BUILD_BUG_ON(IO_CQ_WAKE_FORCE <= IORING_MAX_CQ_ENTRIES);
+
+ /*
+ * We don't know how many requests there are in the link and whether
+ * they can even be queued lazily, fall back to non-lazy.
+ */
+ if (req->flags & IO_REQ_LINK_FLAGS)
+ flags &= ~IOU_F_TWQ_LAZY_WAKE;
+
+ guard(rcu)();
+
+ head = READ_ONCE(ctx->work_llist.first);
+ do {
+ nr_tw_prev = 0;
+ if (head) {
+ struct io_kiocb *first_req = container_of(head,
+ struct io_kiocb,
+ io_task_work.node);
+ /*
+ * Might be executed at any moment, rely on
+ * SLAB_TYPESAFE_BY_RCU to keep it alive.
+ */
+ nr_tw_prev = READ_ONCE(first_req->nr_tw);
+ }
+
+ /*
+ * Theoretically, it can overflow, but that's fine as one of
+ * previous adds should've tried to wake the task.
+ */
+ nr_tw = nr_tw_prev + 1;
+ if (!(flags & IOU_F_TWQ_LAZY_WAKE))
+ nr_tw = IO_CQ_WAKE_FORCE;
+
+ req->nr_tw = nr_tw;
+ req->io_task_work.node.next = head;
+ } while (!try_cmpxchg(&ctx->work_llist.first, &head,
+ &req->io_task_work.node));
+
+ /*
+ * cmpxchg implies a full barrier, which pairs with the barrier
+ * in set_current_state() on the io_cqring_wait() side. It's used
+ * to ensure that either we see updated ->cq_wait_nr, or waiters
+ * going to sleep will observe the work added to the list, which
+ * is similar to the wait/wawke task state sync.
+ */
+
+ if (!head) {
+ if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+ atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+ if (ctx->has_evfd)
+ io_eventfd_signal(ctx, false);
+ }
+
+ nr_wait = atomic_read(&ctx->cq_wait_nr);
+ /* not enough or no one is waiting */
+ if (nr_tw < nr_wait)
+ return;
+ /* the previous add has already woken it up */
+ if (nr_tw_prev >= nr_wait)
+ return;
+ wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
+}
+
+void io_req_normal_work_add(struct io_kiocb *req)
+{
+ struct io_uring_task *tctx = req->tctx;
+ struct io_ring_ctx *ctx = req->ctx;
+
+ /* task_work already pending, we're done */
+ if (!llist_add(&req->io_task_work.node, &tctx->task_list))
+ return;
+
+ if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+ atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+
+ /* SQPOLL doesn't need the task_work added, it'll run it itself */
+ if (ctx->flags & IORING_SETUP_SQPOLL) {
+ __set_notify_signal(tctx->task);
+ return;
+ }
+
+ if (likely(!task_work_add(tctx->task, &tctx->task_work, ctx->notify_method)))
+ return;
+
+ io_fallback_tw(tctx, false);
+}
+
+void io_req_task_work_add_remote(struct io_kiocb *req, unsigned flags)
+{
+ if (WARN_ON_ONCE(!(req->ctx->flags & IORING_SETUP_DEFER_TASKRUN)))
+ return;
+ __io_req_task_work_add(req, flags);
+}
+
+void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
+{
+ struct llist_node *node = llist_del_all(&ctx->work_llist);
+
+ __io_fallback_tw(node, false);
+ node = llist_del_all(&ctx->retry_llist);
+ __io_fallback_tw(node, false);
+}
+
+static bool io_run_local_work_continue(struct io_ring_ctx *ctx, int events,
+ int min_events)
+{
+ if (!io_local_work_pending(ctx))
+ return false;
+ if (events < min_events)
+ return true;
+ if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+ atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+ return false;
+}
+
+static int __io_run_local_work_loop(struct llist_node **node,
+ io_tw_token_t tw,
+ int events)
+{
+ int ret = 0;
+
+ while (*node) {
+ struct llist_node *next = (*node)->next;
+ struct io_kiocb *req = container_of(*node, struct io_kiocb,
+ io_task_work.node);
+ INDIRECT_CALL_2(req->io_task_work.func,
+ io_poll_task_func, io_req_rw_complete,
+ (struct io_tw_req){req}, tw);
+ *node = next;
+ if (++ret >= events)
+ break;
+ }
+
+ return ret;
+}
+
+static int __io_run_local_work(struct io_ring_ctx *ctx, io_tw_token_t tw,
+ int min_events, int max_events)
+{
+ struct llist_node *node;
+ unsigned int loops = 0;
+ int ret = 0;
+
+ if (WARN_ON_ONCE(ctx->submitter_task != current))
+ return -EEXIST;
+ if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+ atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+again:
+ tw.cancel = io_should_terminate_tw(ctx);
+ min_events -= ret;
+ ret = __io_run_local_work_loop(&ctx->retry_llist.first, tw, max_events);
+ if (ctx->retry_llist.first)
+ goto retry_done;
+
+ /*
+ * llists are in reverse order, flip it back the right way before
+ * running the pending items.
+ */
+ node = llist_reverse_order(llist_del_all(&ctx->work_llist));
+ ret += __io_run_local_work_loop(&node, tw, max_events - ret);
+ ctx->retry_llist.first = node;
+ loops++;
+
+ if (io_run_local_work_continue(ctx, ret, min_events))
+ goto again;
+retry_done:
+ io_submit_flush_completions(ctx);
+ if (io_run_local_work_continue(ctx, ret, min_events))
+ goto again;
+
+ trace_io_uring_local_work_run(ctx, ret, loops);
+ return ret;
+}
+
+int io_run_local_work_locked(struct io_ring_ctx *ctx, int min_events)
+{
+ struct io_tw_state ts = {};
+
+ if (!io_local_work_pending(ctx))
+ return 0;
+ return __io_run_local_work(ctx, ts, min_events,
+ max(IO_LOCAL_TW_DEFAULT_MAX, min_events));
+}
+
+int io_run_local_work(struct io_ring_ctx *ctx, int min_events, int max_events)
+{
+ struct io_tw_state ts = {};
+ int ret;
+
+ mutex_lock(&ctx->uring_lock);
+ ret = __io_run_local_work(ctx, ts, min_events, max_events);
+ mutex_unlock(&ctx->uring_lock);
+ return ret;
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#ifndef IOU_TW_H
+#define IOU_TW_H
+
+#include <linux/sched.h>
+#include <linux/percpu-refcount.h>
+#include <linux/io_uring_types.h>
+
+#define IO_LOCAL_TW_DEFAULT_MAX 20
+
+/*
+ * No waiters. It's larger than any valid value of the tw counter
+ * so that tests against ->cq_wait_nr would fail and skip wake_up().
+ */
+#define IO_CQ_WAKE_INIT (-1U)
+/* Forced wake up if there is a waiter regardless of ->cq_wait_nr */
+#define IO_CQ_WAKE_FORCE (IO_CQ_WAKE_INIT >> 1)
+
+/*
+ * Terminate the request if either of these conditions are true:
+ *
+ * 1) It's being executed by the original task, but that task is marked
+ * with PF_EXITING as it's exiting.
+ * 2) PF_KTHREAD is set, in which case the invoker of the task_work is
+ * our fallback task_work.
+ * 3) The ring has been closed and is going away.
+ */
+static inline bool io_should_terminate_tw(struct io_ring_ctx *ctx)
+{
+ return (current->flags & (PF_EXITING | PF_KTHREAD)) || percpu_ref_is_dying(&ctx->refs);
+}
+
+void io_req_task_work_add_remote(struct io_kiocb *req, unsigned flags);
+struct llist_node *io_handle_tw_list(struct llist_node *node, unsigned int *count, unsigned int max_entries);
+void tctx_task_work(struct callback_head *cb);
+int io_run_local_work(struct io_ring_ctx *ctx, int min_events, int max_events);
+int io_run_task_work_sig(struct io_ring_ctx *ctx);
+
+__cold void io_fallback_req_func(struct work_struct *work);
+__cold void io_move_task_work_from_local(struct io_ring_ctx *ctx);
+int io_run_local_work_locked(struct io_ring_ctx *ctx, int min_events);
+
+void io_req_local_work_add(struct io_kiocb *req, unsigned flags);
+void io_req_normal_work_add(struct io_kiocb *req);
+struct llist_node *tctx_task_work_run(struct io_uring_task *tctx, unsigned int max_entries, unsigned int *count);
+
+static inline void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
+{
+ if (req->ctx->flags & IORING_SETUP_DEFER_TASKRUN)
+ io_req_local_work_add(req, flags);
+ else
+ io_req_normal_work_add(req);
+}
+
+static inline void io_req_task_work_add(struct io_kiocb *req)
+{
+ __io_req_task_work_add(req, 0);
+}
+
+static inline int io_run_task_work(void)
+{
+ bool ret = false;
+
+ /*
+ * Always check-and-clear the task_work notification signal. With how
+ * signaling works for task_work, we can find it set with nothing to
+ * run. We need to clear it for that case, like get_signal() does.
+ */
+ if (test_thread_flag(TIF_NOTIFY_SIGNAL))
+ clear_notify_signal();
+ /*
+ * PF_IO_WORKER never returns to userspace, so check here if we have
+ * notify work that needs processing.
+ */
+ if (current->flags & PF_IO_WORKER) {
+ if (test_thread_flag(TIF_NOTIFY_RESUME)) {
+ __set_current_state(TASK_RUNNING);
+ resume_user_mode_work(NULL);
+ }
+ if (current->io_uring) {
+ unsigned int count = 0;
+
+ __set_current_state(TASK_RUNNING);
+ tctx_task_work_run(current->io_uring, UINT_MAX, &count);
+ if (count)
+ ret = true;
+ }
+ }
+ if (task_work_pending(current)) {
+ __set_current_state(TASK_RUNNING);
+ task_work_run();
+ ret = true;
+ }
+
+ return ret;
+}
+
+static inline bool io_local_work_pending(struct io_ring_ctx *ctx)
+{
+ return !llist_empty(&ctx->work_llist) || !llist_empty(&ctx->retry_llist);
+}
+
+static inline bool io_task_work_pending(struct io_ring_ctx *ctx)
+{
+ return task_work_pending(current) || io_local_work_pending(ctx);
+}
+
+static inline void io_tw_lock(struct io_ring_ctx *ctx, io_tw_token_t tw)
+{
+ lockdep_assert_held(&ctx->uring_lock);
+}
+
+static inline bool io_allowed_defer_tw_run(struct io_ring_ctx *ctx)
+{
+ return likely(ctx->submitter_task == current);
+}
+
+static inline bool io_allowed_run_tw(struct io_ring_ctx *ctx)
+{
+ return likely(!(ctx->flags & IORING_SETUP_DEFER_TASKRUN) ||
+ ctx->submitter_task == current);
+}
+
+#endif
projects / thirdparty / kernel / linux.git / commitdiff
