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authorMichel Lespinasse <walken@google.com>2011-03-11 05:48:51 +0300
committerThomas Gleixner <tglx@linutronix.de>2011-03-11 14:23:08 +0300
commit37a9d912b24f96a0591773e6e6c3642991ae5a70 (patch)
tree5c4d5b9a52e2c533269e589115afbd25b6c8534b /arch/parisc
parent522d7decc0370070448a8c28982c8dfd8970489e (diff)
downloadlinux-37a9d912b24f96a0591773e6e6c3642991ae5a70.tar.xz
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 <walken@google.com> Acked-by: Chris Metcalf <cmetcalf@tilera.com> [tile] Acked-by: Tony Luck <tony.luck@intel.com> [ia64] Acked-by: Thomas 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: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/parisc')
-rw-r--r--arch/parisc/include/asm/futex.h18
1 files changed, 9 insertions, 9 deletions
diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h
index 0c705c3a55ef..4c6d8672325b 100644
--- a/arch/parisc/include/asm/futex.h
+++ b/arch/parisc/include/asm/futex.h
@@ -51,10 +51,10 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
/* Non-atomic version */
static inline int
-futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
+futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr,
+ int oldval, int newval)
{
- int err = 0;
- int uval;
+ int val;
/* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
* our gateway page, and causes no end of trouble...
@@ -65,12 +65,12 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
return -EFAULT;
- err = get_user(uval, uaddr);
- if (err) return -EFAULT;
- if (uval == oldval)
- err = put_user(newval, uaddr);
- if (err) return -EFAULT;
- return uval;
+ if (get_user(val, uaddr))
+ return -EFAULT;
+ if (val == oldval && put_user(newval, uaddr))
+ return -EFAULT;
+ *uval = val;
+ return 0;
}
#endif /*__KERNEL__*/