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Fri, 22 Nov 2024 08:16:54 -0800 (PST) Received: from localhost.localdomain ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5f06976585esm436958eaf.18.2024.11.22.08.16.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Nov 2024 08:16:54 -0800 (PST) From: Jens Axboe To: io-uring@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 4/6] io_uring: switch non-defer task_work to io_wq_work_list Date: Fri, 22 Nov 2024 09:12:42 -0700 Message-ID: <20241122161645.494868-5-axboe@kernel.dk> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20241122161645.494868-1-axboe@kernel.dk> References: <20241122161645.494868-1-axboe@kernel.dk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Switch the normal task_work to io_wq_work_list as well, to both unify with defer task_work, but also to avoid needing to reverse the ordering of the list when running it. Note that this still keeps the manual retry list for SQPOLL task_work. That could go away as well, as now the task_work list is fully ordered and SQPOLL could just leave entries on there when it chops up the running of the list. Signed-off-by: Jens Axboe --- include/linux/io_uring_types.h | 14 ++- io_uring/io_uring.c | 167 ++++++++++++++++++++------------- io_uring/io_uring.h | 6 +- io_uring/sqpoll.c | 8 +- io_uring/tctx.c | 3 +- 5 files changed, 116 insertions(+), 82 deletions(-) diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index e9ba99cb0ed0..7ddac4d1d4b3 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -102,7 +102,8 @@ struct io_uring_task { struct percpu_counter inflight; struct { /* task_work */ - struct llist_head task_list; + struct io_wq_work_list task_list; + spinlock_t task_lock; struct callback_head task_work; } ____cacheline_aligned_in_smp; }; @@ -390,8 +391,9 @@ struct io_ring_ctx { struct mm_struct *mm_account; /* ctx exit and cancelation */ - struct llist_head fallback_llist; - struct delayed_work fallback_work; + struct io_wq_work_list fallback_list; + spinlock_t fallback_lock; + struct work_struct fallback_work; struct work_struct exit_work; struct list_head tctx_list; struct completion ref_comp; @@ -567,11 +569,7 @@ enum { typedef void (*io_req_tw_func_t)(struct io_kiocb *req, struct io_tw_state *ts); struct io_task_work { - /* DEFER_TASKRUN uses work_node, regular task_work node */ - union { - struct io_wq_work_node work_node; - struct llist_node node; - }; + struct io_wq_work_node node; io_req_tw_func_t func; }; diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index b7eb962e9872..3bb93c77ac3f 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -245,15 +245,26 @@ static __cold void io_ring_ctx_ref_free(struct percpu_ref *ref) 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; + fallback_work); + struct io_wq_work_node *node; struct io_tw_state ts = {}; + struct io_wq_work_list list; + + spin_lock_irq(&ctx->fallback_lock); + list = ctx->fallback_list; + INIT_WQ_LIST(&ctx->fallback_list); + spin_unlock_irq(&ctx->fallback_lock); percpu_ref_get(&ctx->refs); mutex_lock(&ctx->uring_lock); - llist_for_each_entry_safe(req, tmp, node, io_task_work.node) + node = list.first; + while (node) { + struct io_kiocb *req; + + req = container_of(node, struct io_kiocb, io_task_work.node); + node = node->next; req->io_task_work.func(req, &ts); + } io_submit_flush_completions(ctx); mutex_unlock(&ctx->uring_lock); percpu_ref_put(&ctx->refs); @@ -347,7 +358,9 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) #ifdef CONFIG_FUTEX INIT_HLIST_HEAD(&ctx->futex_list); #endif - INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func); + INIT_WORK(&ctx->fallback_work, io_fallback_req_func); + INIT_WQ_LIST(&ctx->fallback_list); + spin_lock_init(&ctx->fallback_lock); INIT_WQ_LIST(&ctx->submit_state.compl_reqs); INIT_HLIST_HEAD(&ctx->cancelable_uring_cmd); io_napi_init(ctx); @@ -1033,15 +1046,15 @@ static void ctx_flush_and_put(struct io_ring_ctx *ctx, struct io_tw_state *ts) * 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_wq_work_node *io_handle_tw_list(struct io_wq_work_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_wq_work_node *next = node->next; struct io_kiocb *req = container_of(node, struct io_kiocb, io_task_work.node); @@ -1067,55 +1080,84 @@ struct llist_node *io_handle_tw_list(struct llist_node *node, return node; } -static __cold void __io_fallback_tw(struct io_kiocb *req, bool sync, - struct io_ring_ctx **last_ctx) +static __cold void __io_fallback_schedule(struct io_ring_ctx *ctx, + struct io_wq_work_list *list, + bool sync) { - if (sync && *last_ctx != req->ctx) { - if (*last_ctx) { - 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, &req->ctx->fallback_llist)) - schedule_delayed_work(&req->ctx->fallback_work, 1); + bool kick_work = true; + unsigned long flags; + + spin_lock_irqsave(&ctx->fallback_lock, flags); + kick_work = !wq_list_splice_list(list, &ctx->fallback_list); + spin_unlock_irqrestore(&ctx->fallback_lock, flags); + if (kick_work) + schedule_work(&ctx->fallback_work); + + if (sync) + flush_work(&ctx->fallback_work); + percpu_ref_put(&ctx->refs); } -static void io_fallback_tw(struct io_uring_task *tctx, bool sync) +static void __io_fallback_tw(struct io_wq_work_list *list, spinlock_t *lock, + bool sync) { - struct llist_node *node = llist_del_all(&tctx->task_list); + struct io_wq_work_list local_list, ctx_list; struct io_ring_ctx *last_ctx = NULL; + struct io_wq_work_node *node; struct io_kiocb *req; + unsigned long flags; + + spin_lock_irqsave(lock, flags); + local_list = *list; + INIT_WQ_LIST(list); + spin_unlock_irqrestore(lock, flags); + INIT_WQ_LIST(&ctx_list); + node = local_list.first; while (node) { + struct io_wq_work_node *next = node->next; + req = container_of(node, struct io_kiocb, io_task_work.node); - node = node->next; - __io_fallback_tw(req, sync, &last_ctx); + if (last_ctx != req->ctx) { + if (last_ctx) + __io_fallback_schedule(last_ctx, &ctx_list, sync); + last_ctx = req->ctx; + percpu_ref_get(&last_ctx->refs); + } + wq_list_add_tail(node, &ctx_list); + node = next; } - if (last_ctx) { - flush_delayed_work(&last_ctx->fallback_work); - percpu_ref_put(&last_ctx->refs); - } + if (last_ctx) + __io_fallback_schedule(last_ctx, &ctx_list, sync); +} + +static void io_fallback_tw(struct io_uring_task *tctx, bool sync) +{ + __io_fallback_tw(&tctx->task_list, &tctx->task_lock, sync); } -struct llist_node *tctx_task_work_run(struct io_uring_task *tctx, - unsigned int max_entries, - unsigned int *count) +struct io_wq_work_node *tctx_task_work_run(struct io_uring_task *tctx, + unsigned int max_entries, + unsigned int *count) { - struct llist_node *node; + struct io_wq_work_node *node; if (unlikely(current->flags & PF_EXITING)) { io_fallback_tw(tctx, true); return NULL; } - node = llist_del_all(&tctx->task_list); - if (node) { - node = llist_reverse_order(node); + if (!READ_ONCE(tctx->task_list.first)) + return NULL; + + spin_lock_irq(&tctx->task_lock); + node = tctx->task_list.first; + INIT_WQ_LIST(&tctx->task_list); + spin_unlock_irq(&tctx->task_lock); + + if (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))) @@ -1128,13 +1170,11 @@ struct llist_node *tctx_task_work_run(struct io_uring_task *tctx, 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); + if (tctx_task_work_run(tctx, UINT_MAX, &count)) + WARN_ON_ONCE(1); } static inline void io_req_local_work_add(struct io_kiocb *req, @@ -1155,7 +1195,7 @@ static inline void io_req_local_work_add(struct io_kiocb *req, tw_flags &= ~IOU_F_TWQ_LAZY_WAKE; spin_lock_irqsave(&ctx->work_lock, flags); - wq_list_add_tail(&req->io_task_work.work_node, &ctx->work_list); + wq_list_add_tail(&req->io_task_work.node, &ctx->work_list); nr_tw_prev = ctx->work_items++; spin_unlock_irqrestore(&ctx->work_lock, flags); @@ -1192,9 +1232,16 @@ 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; + unsigned long flags; + bool was_empty; + + spin_lock_irqsave(&tctx->task_lock, flags); + was_empty = tctx->task_list.first == NULL; + wq_list_add_tail(&req->io_task_work.node, &tctx->task_list); + spin_unlock_irqrestore(&tctx->task_lock, flags); /* task_work already pending, we're done */ - if (!llist_add(&req->io_task_work.node, &tctx->task_list)) + if (!was_empty) return; if (ctx->flags & IORING_SETUP_TASKRUN_FLAG) @@ -1233,27 +1280,13 @@ void io_req_task_work_add_remote(struct io_kiocb *req, struct io_ring_ctx *ctx, static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx) { - struct io_ring_ctx *last_ctx = NULL; - struct io_wq_work_node *node; - unsigned long flags; - - spin_lock_irqsave(&ctx->work_lock, flags); - node = ctx->work_list.first; - INIT_WQ_LIST(&ctx->work_list); - ctx->work_items = 0; - spin_unlock_irqrestore(&ctx->work_lock, flags); - - while (node) { - struct io_kiocb *req; - - req = container_of(node, struct io_kiocb, io_task_work.work_node); - node = node->next; - __io_fallback_tw(req, false, &last_ctx); - } - if (last_ctx) { - flush_delayed_work(&last_ctx->fallback_work); - percpu_ref_put(&last_ctx->refs); - } + /* + * __io_fallback_tw() handles lists that can have multiple + * rings in it, which isn't the case here. But it'll work just + * fine, so use it anyway rather than have a special case for + * just a single ctx. + */ + __io_fallback_tw(&ctx->work_list, &ctx->work_lock, false); } static bool io_run_local_work_continue(struct io_ring_ctx *ctx, int events, @@ -1292,7 +1325,7 @@ static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts, while (node) { struct io_kiocb *req = container_of(node, struct io_kiocb, - io_task_work.work_node); + io_task_work.node); node = node->next; INDIRECT_CALL_2(req->io_task_work.func, io_poll_task_func, io_req_rw_complete, @@ -2967,7 +3000,7 @@ static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) io_unregister_personality(ctx, index); mutex_unlock(&ctx->uring_lock); - flush_delayed_work(&ctx->fallback_work); + flush_work(&ctx->fallback_work); INIT_WORK(&ctx->exit_work, io_ring_exit_work); /* @@ -3106,7 +3139,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, if (tctx) ret |= io_run_task_work() > 0; else - ret |= flush_delayed_work(&ctx->fallback_work); + ret |= flush_work(&ctx->fallback_work); return ret; } diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h index 2fae27803116..0b5181b128aa 100644 --- a/io_uring/io_uring.h +++ b/io_uring/io_uring.h @@ -91,8 +91,10 @@ void io_req_task_queue(struct io_kiocb *req); void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts); void io_req_task_queue_fail(struct io_kiocb *req, int ret); void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts); -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); +struct io_wq_work_node *io_handle_tw_list(struct io_wq_work_node *node, + unsigned int *count, unsigned int max_entries); +struct io_wq_work_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_cancel_generic(bool cancel_all, struct io_sq_data *sqd); int io_uring_alloc_task_context(struct task_struct *task, diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c index 6df5e649c413..615707260f25 100644 --- a/io_uring/sqpoll.c +++ b/io_uring/sqpoll.c @@ -221,7 +221,7 @@ static bool io_sqd_handle_event(struct io_sq_data *sqd) * than we were asked to process. Newly queued task_work isn't run until the * retry list has been fully processed. */ -static unsigned int io_sq_tw(struct llist_node **retry_list, int max_entries) +static unsigned int io_sq_tw(struct io_wq_work_node **retry_list, int max_entries) { struct io_uring_task *tctx = current->io_uring; unsigned int count = 0; @@ -239,11 +239,11 @@ static unsigned int io_sq_tw(struct llist_node **retry_list, int max_entries) return count; } -static bool io_sq_tw_pending(struct llist_node *retry_list) +static bool io_sq_tw_pending(struct io_wq_work_node *retry_list) { struct io_uring_task *tctx = current->io_uring; - return retry_list || !llist_empty(&tctx->task_list); + return retry_list || READ_ONCE(tctx->task_list.first); } static void io_sq_update_worktime(struct io_sq_data *sqd, struct rusage *start) @@ -259,7 +259,7 @@ static void io_sq_update_worktime(struct io_sq_data *sqd, struct rusage *start) static int io_sq_thread(void *data) { - struct llist_node *retry_list = NULL; + struct io_wq_work_node *retry_list = NULL; struct io_sq_data *sqd = data; struct io_ring_ctx *ctx; struct rusage start; diff --git a/io_uring/tctx.c b/io_uring/tctx.c index 503f3ff8bc4f..7155b3c56c85 100644 --- a/io_uring/tctx.c +++ b/io_uring/tctx.c @@ -87,7 +87,8 @@ __cold int io_uring_alloc_task_context(struct task_struct *task, atomic_set(&tctx->in_cancel, 0); atomic_set(&tctx->inflight_tracked, 0); task->io_uring = tctx; - init_llist_head(&tctx->task_list); + INIT_WQ_LIST(&tctx->task_list); + spin_lock_init(&tctx->task_lock); init_task_work(&tctx->task_work, tctx_task_work); return 0; }