Re: [PATCH v4.4.y] futex: Ensure the correct return value from futex_lock_pi()

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Mar 02, 2021 at 11:47:49AM -0800, Sharan Turlapati wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> commit 12bb3f7f1b03d5913b3f9d4236a488aa7774dfe9 upstream
> 
> In case that futex_lock_pi() was aborted by a signal or a timeout and the
> task returned without acquiring the rtmutex, but is the designated owner of
> the futex due to a concurrent futex_unlock_pi() fixup_owner() is invoked to
> establish consistent state. In that case it invokes fixup_pi_state_owner()
> which in turn tries to acquire the rtmutex again. If that succeeds then it
> does not propagate this success to fixup_owner() and futex_lock_pi()
> returns -EINTR or -ETIMEOUT despite having the futex locked.
> 
> Return success from fixup_pi_state_owner() in all cases where the current
> task owns the rtmutex and therefore the futex and propagate it correctly
> through fixup_owner(). Fixup the other callsite which does not expect a
> positive return value.
> 
> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: stable@vger.kernel.org
> [Sharan: Backported patch for kernel 4.4.y. Also folded in is a part
>  of the cleanup patch d7c5ed73b19c("futex: Remove needless goto's")]
> Signed-off-by: Sharan Turlapati <sturlapati@vmware.com>
> ---
>  kernel/futex.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)

Now queued up, thanks.

greg k-h