[PATCH] ppc signal handling fixes

2.6.8-rc2-mm1 reintroduced the signal-race-fixes patch for i386, x86_64,
s390, and ia64, breaking all other archs.

The patch below updates ppc, following the pattern of i386.  Compiled &
runtime tested.  No observable breakage.
Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc/kernel/signal.c

@@ -600,7 +600,7 @@ int sys_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
 int do_signal(sigset_t *oldset, struct pt_regs *regs)
 {
 	siginfo_t info;
-	struct k_sigaction *ka;
+	struct k_sigaction ka;
 	unsigned long frame, newsp;
 	int signr, ret;
 
@@ -609,9 +609,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 
 	newsp = frame = 0;
 
-	signr = get_signal_to_deliver(&info, regs, NULL);
-
-	ka = (signr == 0)? NULL: &current->sighand->action[signr-1];
+	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 
 	if (TRAP(regs) == 0x0C00		/* System Call! */
 	    && regs->ccr & 0x10000000		/* error signalled */
@@ -622,7 +620,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 		if (signr > 0
 		    && (ret == ERESTARTNOHAND || ret == ERESTART_RESTARTBLOCK
 			|| (ret == ERESTARTSYS
-			    && !(ka->sa.sa_flags & SA_RESTART)))) {
+			    && !(ka.sa.sa_flags & SA_RESTART)))) {
 			/* make the system call return an EINTR error */
 			regs->result = -EINTR;
 			regs->gpr[3] = EINTR;
@@ -641,7 +639,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 	if (signr == 0)
 		return 0;		/* no signals delivered */
 
-	if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
+	if ((ka.sa.sa_flags & SA_ONSTACK) && current->sas_ss_size
 	    && !on_sig_stack(regs->gpr[1]))
 		newsp = current->sas_ss_sp + current->sas_ss_size;
 	else
@@ -649,17 +647,14 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 	newsp &= ~0xfUL;
 
 	/* Whee!  Actually deliver the signal.  */
-	if (ka->sa.sa_flags & SA_SIGINFO)
-		handle_rt_signal(signr, ka, &info, oldset, regs, newsp);
+	if (ka.sa.sa_flags & SA_SIGINFO)
+		handle_rt_signal(signr, &ka, &info, oldset, regs, newsp);
 	else
-		handle_signal(signr, ka, &info, oldset, regs, newsp);
-
-	if (ka->sa.sa_flags & SA_ONESHOT)
-		ka->sa.sa_handler = SIG_DFL;
+		handle_signal(signr, &ka, &info, oldset, regs, newsp);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
+	if (!(ka.sa.sa_flags & SA_NODEFER)) {
 		spin_lock_irq(&current->sighand->siglock);
-		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+		sigorsets(&current->blocked,&current->blocked,&ka.sa.sa_mask);
 		sigaddset(&current->blocked, signr);
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);