From 37a9d912b24f96a0591773e6e6c3642991ae5a70 Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Thu, 10 Mar 2011 18:48:51 -0800 Subject: futex: Sanitize cmpxchg_futex_value_locked API 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: Michel Lespinasse Acked-by: Chris Metcalf [tile] Acked-by: Tony Luck [ia64] Acked-by: Thomas Gleixner Tested-by: Michal Simek [microblaze] Acked-by: David Howells [frv] Cc: Darren Hart Cc: Peter Zijlstra Cc: Matt Turner Cc: Russell King Cc: Ralf Baechle Cc: "James E.J. Bottomley" Cc: Benjamin Herrenschmidt Cc: Martin Schwidefsky Cc: Paul Mundt Cc: "David S. Miller" Cc: Linus Torvalds LKML-Reference: <20110311024851.GC26122@google.com> Signed-off-by: Thomas Gleixner --- arch/tile/include/asm/futex.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'arch/tile') diff --git a/arch/tile/include/asm/futex.h b/arch/tile/include/asm/futex.h index fe0d10dcae57a..664b20aa2584f 100644 --- a/arch/tile/include/asm/futex.h +++ b/arch/tile/include/asm/futex.h @@ -119,8 +119,8 @@ static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr) return ret; } -static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, - int newval) +static inline int futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { struct __get_user asm_ret; @@ -128,7 +128,8 @@ static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, return -EFAULT; asm_ret = futex_cmpxchg(uaddr, oldval, newval); - return asm_ret.err ? asm_ret.err : asm_ret.val; + *uval = asm_ret.val; + return asm_ret.err; } #ifndef __tilegx__ -- cgit v1.2.3