ARM: prevent multiple syscall restarts

Al Viro reports that calling "sys_sigsuspend(-ERESTARTNOHAND, 0, 0)"
with two signals coming and being handled in kernel space results
in the syscall restart being done twice.

Avoid this by clearing the 'why' flag when we call the signal handling
code to prevent further syscall restarts after the first.

Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f05a35a59694dc7af54a76ffb899e02f8b849875..4a560d30793d568ab6fb3409f669b1a2e37d62ea 100644 (file)
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -48,6 +48,8 @@ work_pending:
        beq     no_work_pending
        mov     r0, sp                          @ 'regs'
        mov     r2, why                         @ 'syscall'
+       tst     r1, #_TIF_SIGPENDING            @ delivering a signal?
+       movne   why, #0                         @ prevent further restarts
        bl      do_notify_resume
        b       ret_slow_syscall                @ Check work again