commit 4c663cfc52 upstream.
Many callers of the wait_event_timeout() and
wait_event_interruptible_timeout() expect that the return value will be
positive if the specified condition becomes true before the timeout
elapses. However, at the moment this isn't guaranteed. If the wake-up
handler is delayed enough, the time remaining until timeout will be
calculated as 0 - and passed back as a return value - even if the
condition became true before the timeout has passed.
Fix this by returning at least 1 if the condition becomes true. This
semantic is in line with what wait_for_condition_timeout() does; see
commit bb10ed09 ("sched: fix wait_for_completion_timeout() spurious
failure under heavy load").
Daniel said "We have 3 instances of this bug in drm/i915. One case even
where we switch between the interruptible and not interruptible
wait_event_timeout variants, foolishly presuming they have the same
semantics. I very much like this."
One such bug is reported at
https://bugs.freedesktop.org/show_bug.cgi?id=64133
Signed-off-by: Imre Deak <imre.deak@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 0720a06a75 upstream.
The utf8s_to_utf16s conversion routine needs to be improved. Unlike
its utf16s_to_utf8s sibling, it doesn't accept arguments specifying
the maximum length of the output buffer or the endianness of its
16-bit output.
This patch (as1501) adds the two missing arguments, and adjusts the
only two places in the kernel where the function is called. A
follow-on patch will add a third caller that does utilize the new
capabilities.
The two conversion routines are still annoyingly inconsistent in the
way they handle invalid byte combinations. But that's a subject for a
different patch.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
