forked from Minki/linux
io_uring: batch task work locking
Many task_work handlers either grab ->uring_lock, or may benefit from having it. Move locking logic out of individual handlers to a lazy approach controlled by tctx_task_work(), so we don't keep doing tons of mutex lock/unlock. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d6a34e147f2507a2f3e2fa1e38a9c541dcad3929.1629286357.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
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5636c00d3e
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f237c30a56
@ -775,7 +775,7 @@ struct async_poll {
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struct io_poll_iocb *double_poll;
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};
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typedef void (*io_req_tw_func_t)(struct io_kiocb *req);
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typedef void (*io_req_tw_func_t)(struct io_kiocb *req, bool *locked);
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struct io_task_work {
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union {
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@ -1080,6 +1080,14 @@ struct sock *io_uring_get_socket(struct file *file)
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}
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EXPORT_SYMBOL(io_uring_get_socket);
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static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
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{
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if (!*locked) {
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mutex_lock(&ctx->uring_lock);
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*locked = true;
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}
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}
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#define io_for_each_link(pos, head) \
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for (pos = (head); pos; pos = pos->link)
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@ -1193,16 +1201,19 @@ static void io_fallback_req_func(struct work_struct *work)
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fallback_work.work);
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struct llist_node *node = llist_del_all(&ctx->fallback_llist);
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struct io_kiocb *req, *tmp;
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bool locked = false;
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percpu_ref_get(&ctx->refs);
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llist_for_each_entry_safe(req, tmp, node, io_task_work.fallback_node)
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req->io_task_work.func(req);
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req->io_task_work.func(req, &locked);
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mutex_lock(&ctx->uring_lock);
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if (ctx->submit_state.compl_nr)
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io_submit_flush_completions(ctx);
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mutex_unlock(&ctx->uring_lock);
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if (locked) {
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if (ctx->submit_state.compl_nr)
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io_submit_flush_completions(ctx);
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mutex_unlock(&ctx->uring_lock);
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}
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percpu_ref_put(&ctx->refs);
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}
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static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
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@ -1386,12 +1397,15 @@ static void io_prep_async_link(struct io_kiocb *req)
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}
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}
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static void io_queue_async_work(struct io_kiocb *req)
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static void io_queue_async_work(struct io_kiocb *req, bool *locked)
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct io_kiocb *link = io_prep_linked_timeout(req);
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struct io_uring_task *tctx = req->task->io_uring;
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/* must not take the lock, NULL it as a precaution */
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locked = NULL;
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BUG_ON(!tctx);
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BUG_ON(!tctx->io_wq);
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@ -2013,21 +2027,22 @@ static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
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return __io_req_find_next(req);
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}
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static void ctx_flush_and_put(struct io_ring_ctx *ctx)
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static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
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{
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if (!ctx)
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return;
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if (ctx->submit_state.compl_nr) {
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mutex_lock(&ctx->uring_lock);
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if (*locked) {
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if (ctx->submit_state.compl_nr)
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io_submit_flush_completions(ctx);
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mutex_unlock(&ctx->uring_lock);
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*locked = false;
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}
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percpu_ref_put(&ctx->refs);
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}
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static void tctx_task_work(struct callback_head *cb)
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{
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bool locked = false;
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struct io_ring_ctx *ctx = NULL;
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struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
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task_work);
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@ -2050,18 +2065,18 @@ static void tctx_task_work(struct callback_head *cb)
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io_task_work.node);
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if (req->ctx != ctx) {
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ctx_flush_and_put(ctx);
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ctx_flush_and_put(ctx, &locked);
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ctx = req->ctx;
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percpu_ref_get(&ctx->refs);
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}
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req->io_task_work.func(req);
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req->io_task_work.func(req, &locked);
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node = next;
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} while (node);
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cond_resched();
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}
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ctx_flush_and_put(ctx);
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ctx_flush_and_put(ctx, &locked);
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}
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static void io_req_task_work_add(struct io_kiocb *req)
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@ -2113,28 +2128,26 @@ static void io_req_task_work_add(struct io_kiocb *req)
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}
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}
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static void io_req_task_cancel(struct io_kiocb *req)
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static void io_req_task_cancel(struct io_kiocb *req, bool *locked)
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{
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struct io_ring_ctx *ctx = req->ctx;
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/* ctx is guaranteed to stay alive while we hold uring_lock */
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mutex_lock(&ctx->uring_lock);
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io_tw_lock(ctx, locked);
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io_req_complete_failed(req, req->result);
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mutex_unlock(&ctx->uring_lock);
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}
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static void io_req_task_submit(struct io_kiocb *req)
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static void io_req_task_submit(struct io_kiocb *req, bool *locked)
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{
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struct io_ring_ctx *ctx = req->ctx;
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/* ctx stays valid until unlock, even if we drop all ours ctx->refs */
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mutex_lock(&ctx->uring_lock);
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io_tw_lock(ctx, locked);
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/* req->task == current here, checking PF_EXITING is safe */
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if (likely(!(req->task->flags & PF_EXITING)))
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__io_queue_sqe(req);
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else
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io_req_complete_failed(req, -EFAULT);
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mutex_unlock(&ctx->uring_lock);
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}
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static void io_req_task_queue_fail(struct io_kiocb *req, int ret)
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@ -2170,6 +2183,11 @@ static void io_free_req(struct io_kiocb *req)
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__io_free_req(req);
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}
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static void io_free_req_work(struct io_kiocb *req, bool *locked)
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{
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io_free_req(req);
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}
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struct req_batch {
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struct task_struct *task;
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int task_refs;
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@ -2267,7 +2285,7 @@ static inline void io_put_req(struct io_kiocb *req)
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static inline void io_put_req_deferred(struct io_kiocb *req)
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{
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if (req_ref_put_and_test(req)) {
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req->io_task_work.func = io_free_req;
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req->io_task_work.func = io_free_req_work;
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io_req_task_work_add(req);
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}
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}
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@ -2562,7 +2580,7 @@ static bool __io_complete_rw_common(struct io_kiocb *req, long res)
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return false;
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}
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static void io_req_task_complete(struct io_kiocb *req)
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static void io_req_task_complete(struct io_kiocb *req, bool *locked)
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{
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__io_req_complete(req, 0, req->result, io_put_rw_kbuf(req));
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}
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@ -2572,7 +2590,7 @@ static void __io_complete_rw(struct io_kiocb *req, long res, long res2,
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{
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if (__io_complete_rw_common(req, res))
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return;
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io_req_task_complete(req);
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__io_req_complete(req, 0, req->result, io_put_rw_kbuf(req));
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}
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static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
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@ -4994,7 +5012,7 @@ static bool io_poll_complete(struct io_kiocb *req, __poll_t mask)
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return !(flags & IORING_CQE_F_MORE);
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}
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static void io_poll_task_func(struct io_kiocb *req)
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static void io_poll_task_func(struct io_kiocb *req, bool *locked)
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{
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struct io_ring_ctx *ctx = req->ctx;
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struct io_kiocb *nxt;
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@ -5018,7 +5036,7 @@ static void io_poll_task_func(struct io_kiocb *req)
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if (done) {
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nxt = io_put_req_find_next(req);
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if (nxt)
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io_req_task_submit(nxt);
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io_req_task_submit(nxt, locked);
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}
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}
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}
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@ -5130,7 +5148,7 @@ static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,
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__io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll);
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}
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static void io_async_task_func(struct io_kiocb *req)
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static void io_async_task_func(struct io_kiocb *req, bool *locked)
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{
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struct async_poll *apoll = req->apoll;
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struct io_ring_ctx *ctx = req->ctx;
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@ -5147,7 +5165,7 @@ static void io_async_task_func(struct io_kiocb *req)
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spin_unlock(&ctx->completion_lock);
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if (!READ_ONCE(apoll->poll.canceled))
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io_req_task_submit(req);
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io_req_task_submit(req, locked);
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else
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io_req_complete_failed(req, -ECANCELED);
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}
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@ -5546,7 +5564,7 @@ err:
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return 0;
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}
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static void io_req_task_timeout(struct io_kiocb *req)
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static void io_req_task_timeout(struct io_kiocb *req, bool *locked)
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{
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req_set_fail(req);
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io_req_complete_post(req, -ETIME, 0);
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@ -6103,7 +6121,7 @@ fail:
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if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
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spin_unlock(&ctx->completion_lock);
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kfree(de);
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io_queue_async_work(req);
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io_queue_async_work(req, NULL);
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return true;
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}
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@ -6425,7 +6443,7 @@ static inline struct file *io_file_get(struct io_ring_ctx *ctx,
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return io_file_get_normal(ctx, req, fd);
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}
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static void io_req_task_link_timeout(struct io_kiocb *req)
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static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
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{
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struct io_kiocb *prev = req->timeout.prev;
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int ret;
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@ -6529,7 +6547,7 @@ issue_sqe:
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* Queued up for async execution, worker will release
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* submit reference when the iocb is actually submitted.
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*/
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io_queue_async_work(req);
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io_queue_async_work(req, NULL);
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break;
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}
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@ -6554,7 +6572,7 @@ static inline void io_queue_sqe(struct io_kiocb *req)
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if (unlikely(ret))
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io_req_complete_failed(req, ret);
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else
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io_queue_async_work(req);
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io_queue_async_work(req, NULL);
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}
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}
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