[RFC PATCH 10/10] pipe: Check for ring full inside of the spinlock in pipe_write() [ver #2]
From: David Howells <dhowells@redhat.com>
Date: 2019-10-23 20:18:45
Also in:
keyrings, linux-block, linux-fsdevel, linux-security-module, linux-usb, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Make pipe_write() check to see if the ring has become full between it taking the pipe mutex, checking the ring status and then taking the spinlock. This can happen if a notification is written into the pipe as that happens without the pipe mutex. Signed-off-by: David Howells <dhowells@redhat.com> --- fs/pipe.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/fs/pipe.c b/fs/pipe.c
index 3df93990dd9d..6a982a88f658 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c@@ -462,6 +462,11 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) spin_lock_irq(&pipe->wait.lock); head = pipe->head; + if (pipe_full(head, pipe->tail, max_usage)) { + spin_unlock_irq(&pipe->wait.lock); + continue; + } + pipe_commit_write(pipe, head + 1); /* Always wake up, even if the copy fails. Otherwise