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| author | Christian Brauner <brauner@kernel.org> | 2025-01-10 11:59:08 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-01-10 11:59:45 +0100 |
| commit | 67cd2e23c0f353803f182ae790a7d5074d4c1a4d (patch) | |
| tree | 21b4329a819a52e988be56b5faefd9a78255f896 /io_uring | |
| parent | Linux 6.13-rc1 (diff) | |
| parent | poll: kill poll_does_not_wait() (diff) | |
| download | linux-67cd2e23c0f353803f182ae790a7d5074d4c1a4d.tar.xz linux-67cd2e23c0f353803f182ae790a7d5074d4c1a4d.zip | |
Merge patch series "poll_wait: add mb() to fix theoretical race between waitqueue_active() and .poll()"
Oleg Nesterov <oleg@redhat.com> says:
The waitqueue_active() helper can only be used if both waker and waiter
have memory barriers that pair with each other. But __pollwait() is
broken in this respect. Fix it.
* patches from https://lore.kernel.org/r/20250107162649.GA18886@redhat.com:
poll: kill poll_does_not_wait()
sock_poll_wait: kill the no longer necessary barrier after poll_wait()
io_uring_poll: kill the no longer necessary barrier after poll_wait()
poll_wait: kill the obsolete wait_address check
poll_wait: add mb() to fix theoretical race between waitqueue_active() and .poll()
Link: https://lore.kernel.org/r/20250107162649.GA18886@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 06ff41484e29..a64a82b93b86 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2809,13 +2809,12 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait) if (unlikely(!ctx->poll_activated)) io_activate_pollwq(ctx); - - poll_wait(file, &ctx->poll_wq, wait); /* - * synchronizes with barrier from wq_has_sleeper call in - * io_commit_cqring + * provides mb() which pairs with barrier from wq_has_sleeper + * call in io_commit_cqring */ - smp_rmb(); + poll_wait(file, &ctx->poll_wq, wait); + if (!io_sqring_full(ctx)) mask |= EPOLLOUT | EPOLLWRNORM; |