Return 0 if the operation was successful, not the userspace memory value. Check that userspace value equals passed oldval, not itself. Don't update *uval if the value wasn't read from userspace memory.

This fixes process hang due to infinite loop in futex_lock_pi. It also fixes a bunch of glibc tests nptl/tst-mutexpi*.

Cc: stable@vger.kernel.org Signed-off-by: Max Filippov jcmvbkbc@gmail.com --- arch/xtensa/include/asm/futex.h | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/arch/xtensa/include/asm/futex.h b/arch/xtensa/include/asm/futex.h index eaaf1ebcc7a4..5bfbc1c401d4 100644 --- a/arch/xtensa/include/asm/futex.h +++ b/arch/xtensa/include/asm/futex.h @@ -92,7 +92,6 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval, u32 newval) { int ret = 0; - u32 prev;

if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) return -EFAULT; @@ -103,26 +102,24 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,

__asm__ __volatile__ ( " # futex_atomic_cmpxchg_inatomic\n" - "1: l32i %1, %3, 0\n" - " mov %0, %5\n" - " wsr %1, scompare1\n" - "2: s32c1i %0, %3, 0\n" - "3:\n" + " wsr %5, scompare1\n" + "1: s32c1i %1, %4, 0\n" + " s32i %1, %6, 0\n" + "2:\n" " .section .fixup,"ax"\n" " .align 4\n" - "4: .long 3b\n" - "5: l32r %1, 4b\n" - " movi %0, %6\n" + "3: .long 2b\n" + "4: l32r %1, 3b\n" + " movi %0, %7\n" " jx %1\n" " .previous\n" " .section __ex_table,"a"\n" - " .long 1b,5b,2b,5b\n" + " .long 1b,4b\n" " .previous\n" - : "+r" (ret), "=&r" (prev), "+m" (*uaddr) - : "r" (uaddr), "r" (oldval), "r" (newval), "I" (-EFAULT) + : "+r" (ret), "+r" (newval), "+m" (*uaddr), "+m" (*uval) + : "r" (uaddr), "r" (oldval), "r" (uval), "I" (-EFAULT) : "memory");

- *uval = prev; return ret; }