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Thu, 09 Oct 2025 10:41:50 -0700 (PDT) Received: from m2max ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-42f9037c631sm12955045ab.33.2025.10.09.10.41.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Oct 2025 10:41:50 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 2/2] io_uring/waitid: use io_waitid_remove_wq() consistently Date: Thu, 9 Oct 2025 11:39:26 -0600 Message-ID: <20251009174145.2209946-3-axboe@kernel.dk> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251009174145.2209946-1-axboe@kernel.dk> References: <20251009174145.2209946-1-axboe@kernel.dk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Use it everywhere that the wait_queue_entry is removed from the head, and be a bit more cautious in zeroing out iw->head whenever the entry is removed from the list. Signed-off-by: Jens Axboe --- io_uring/waitid.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/io_uring/waitid.c b/io_uring/waitid.c index ebe3769c54dc..c5e0d979903a 100644 --- a/io_uring/waitid.c +++ b/io_uring/waitid.c @@ -179,18 +179,18 @@ bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx, static inline bool io_waitid_drop_issue_ref(struct io_kiocb *req) { struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); - struct io_waitid_async *iwa = req->async_data; if (!atomic_sub_return(1, &iw->refs)) return false; + io_waitid_remove_wq(req); + /* * Wakeup triggered, racing with us. It was prevented from * completing because of that, queue up the tw to do that. */ req->io_task_work.func = io_waitid_cb; io_req_task_work_add(req); - remove_wait_queue(iw->head, &iwa->wo.child_wait); return true; } @@ -245,6 +245,7 @@ static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode, return 0; list_del_init(&wait->entry); + iw->head = NULL; /* cancel is in progress */ if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK) @@ -271,6 +272,7 @@ int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) iw->which = READ_ONCE(sqe->len); iw->upid = READ_ONCE(sqe->fd); iw->options = READ_ONCE(sqe->file_index); + iw->head = NULL; iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2)); return 0; } @@ -301,11 +303,16 @@ int io_waitid(struct io_kiocb *req, unsigned int issue_flags) * callback. */ io_ring_submit_lock(ctx, issue_flags); + + /* + * iw->head is valid under the ring lock, and as long as the request + * is on the waitid_list where cancelations may find it. + */ + iw->head = ¤t->signal->wait_chldexit; hlist_add_head(&req->hash_node, &ctx->waitid_list); init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait); iwa->wo.child_wait.private = req->tctx->task; - iw->head = ¤t->signal->wait_chldexit; add_wait_queue(iw->head, &iwa->wo.child_wait); ret = __do_wait(&iwa->wo); @@ -328,7 +335,7 @@ int io_waitid(struct io_kiocb *req, unsigned int issue_flags) } hlist_del_init(&req->hash_node); - remove_wait_queue(iw->head, &iwa->wo.child_wait); + io_waitid_remove_wq(req); ret = io_waitid_finish(req, ret); io_ring_submit_unlock(ctx, issue_flags); -- 2.51.0