• Michel Lespinasse's avatar
    futex: Sanitize cmpxchg_futex_value_locked API · 37a9d912
    Michel Lespinasse authored
    The cmpxchg_futex_value_locked API was funny in that it returned either
    the original, user-exposed futex value OR an error code such as -EFAULT.
    This was confusing at best, and could be a source of livelocks in places
    that retry the cmpxchg_futex_value_locked after trying to fix the issue
    by running fault_in_user_writeable().
        
    This change makes the cmpxchg_futex_value_locked API more similar to the
    get_futex_value_locked one, returning an error code and updating the
    original value through a reference argument.
    Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
    Acked-by: Chris Metcalf <cmetcalf@tilera.com>  [tile]
    Acked-by: Tony Luck <tony.luck@intel.com>  [ia64]
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Tested-by: Michal Simek <monstr@monstr.eu>  [microblaze]
    Acked-by: David Howells <dhowells@redhat.com> [frv]
    Cc: Darren Hart <darren@dvhart.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Matt Turner <mattst88@gmail.com>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Cc: Paul Mundt <lethal@linux-sh.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    LKML-Reference: <20110311024851.GC26122@google.com>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    37a9d912
futex.h 3.41 KB