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>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f05a35a59694..4a560d30793d 100644
--- 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