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    Subject[RFC PATCH 10/10] pipe: Check for ring full inside of the spinlock in pipe_write() [ver #2]
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    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
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