arm: if we get into work_pending while returning to kernel mode, just go away

checking in do_signal() is pointless - if we get there with !user_mode(regs)
(and we might), we'll end up looping indefinitely.  Check in work_pending
and break out of the loop if so.

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

2 files changed, 3 insertions, 9 deletions

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 82aaf0aeb85d..b669b49d7cc4 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -56,7 +56,10 @@ work_pending:
         /*
          * TIF_SIGPENDING or TIF_NOTIFY_RESUME must've been set if we got here
          */
+        ldr     r2, [sp, #S_PSR]
         mov     r0, sp                          @ 'regs'
+        tst     r2, #15                         @ are we returning to user mode?
+        bne     no_work_pending                 @ no?  just leave, then...
         mov     r2, why                         @ 'syscall'
         tst     r1, #_TIF_SIGPENDING            @ delivering a signal?
         movne   why, #0                         @ prevent further restarts
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 3b37c14c47f5..6b37d4ddf0b6 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -609,15 +609,6 @@ static void do_signal(struct pt_regs *regs, int syscall)
         int signr;
 
         /*
-         * We want the common case to go fast, which
-         * is why we may in certain cases get here from
-         * kernel mode. Just return without doing anything
-         * if so.
-         */
-        if (!user_mode(regs))
-                return;
-
-        /*
          * If we were from a system call, check for system call restarting...
          */
         if (syscall) {