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pipe: wakeup wr_wait after setting max_usage

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Commit c73be61ced ("pipe: Add general notification queue support") a
regression was introduced that would lock up resized pipes under certain
conditions. See the reproducer in [1].

The commit resizing the pipe ring size was moved to a different
function, doing that moved the wakeup for pipe->wr_wait before actually
raising pipe->max_usage. If a pipe was full before the resize occured it
would result in the wakeup never actually triggering pipe_write.

Set @max_usage and @nr_accounted before waking writers if this isn't a
watch queue.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=212295 [1]
Link: https://lore.kernel.org/r/20231201-orchideen-modewelt-e009de4562c6@brauner
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Lukas Schauer <lukas@schauer.dev>
[Christian Brauner <brauner@kernel.org>: rewrite to account for watch queues]
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Lukas Schauer 2023-12-01 11:11:28 +01:00 committed by Christian Brauner
parent 055ca83559
commit e95aada4cb
No known key found for this signature in database
GPG key ID: 91C61BC06578DCA2
1 changed files with 5 additions and 2 deletions
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7
fs/pipe.c
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@ -1324,6 +1324,11 @@ int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
pipe->tail = tail;
pipe->head = head;
if (!pipe_has_watch_queue(pipe)) {
pipe->max_usage = nr_slots;
pipe->nr_accounted = nr_slots;
}
spin_unlock_irq(&pipe->rd_wait.lock);
/* This might have made more room for writers */
@ -1375,8 +1380,6 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned int arg)
if (ret < 0)
goto out_revert_acct;
pipe->max_usage = nr_slots;
pipe->nr_accounted = nr_slots;
return pipe->max_usage * PAGE_SIZE;
out_revert_acct: