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io_uring/waitid: use io_waitid_remove_wq() consistently

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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 <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2025-10-09 10:55:08 -06:00
parent a48c0cbf28
commit ab673c1bca
1 changed files with 11 additions and 4 deletions
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15
io_uring/waitid.c
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@ -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) 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 *iw = io_kiocb_to_cmd(req, struct io_waitid);
struct io_waitid_async *iwa = req->async_data;
if (!atomic_sub_return(1, &iw->refs)) if (!atomic_sub_return(1, &iw->refs))
return false; return false;
io_waitid_remove_wq(req);
/* /*
* Wakeup triggered, racing with us. It was prevented from * Wakeup triggered, racing with us. It was prevented from
* completing because of that, queue up the tw to do that. * completing because of that, queue up the tw to do that.
*/ */
req->io_task_work.func = io_waitid_cb; req->io_task_work.func = io_waitid_cb;
io_req_task_work_add(req); io_req_task_work_add(req);
remove_wait_queue(iw->head, &iwa->wo.child_wait);
return true; return true;
} }
@ -245,6 +245,7 @@ static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode,
return 0; return 0;
list_del_init(&wait->entry); list_del_init(&wait->entry);
iw->head = NULL;
/* cancel is in progress */ /* cancel is in progress */
if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK) 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->which = READ_ONCE(sqe->len);
iw->upid = READ_ONCE(sqe->fd); iw->upid = READ_ONCE(sqe->fd);
iw->options = READ_ONCE(sqe->file_index); iw->options = READ_ONCE(sqe->file_index);
iw->head = NULL;
iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2)); iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2));
return 0; return 0;
} }
@ -301,11 +303,16 @@ int io_waitid(struct io_kiocb *req, unsigned int issue_flags)
* callback. * callback.
*/ */
io_ring_submit_lock(ctx, issue_flags); 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 = &current->signal->wait_chldexit;
hlist_add_head(&req->hash_node, &ctx->waitid_list); hlist_add_head(&req->hash_node, &ctx->waitid_list);
init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait); init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait);
iwa->wo.child_wait.private = req->tctx->task; iwa->wo.child_wait.private = req->tctx->task;
iw->head = &current->signal->wait_chldexit;
add_wait_queue(iw->head, &iwa->wo.child_wait); add_wait_queue(iw->head, &iwa->wo.child_wait);
ret = __do_wait(&iwa->wo); 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); 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); ret = io_waitid_finish(req, ret);
io_ring_submit_unlock(ctx, issue_flags); io_ring_submit_unlock(ctx, issue_flags);