From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Fri, 6 Jul 2012 00:34:02 +0000 (+1000)
Subject: Revert "arm: deal with handlerless restarts without leaving the kernel"
X-Git-Tag: next-20120724~4^2~1
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=42148731e0a6fa44ce94b493f5dfeefe9dec63ac;p=karo-tx-linux.git

Revert "arm: deal with handlerless restarts without leaving the kernel"

This reverts commit 9c802c169f964830496be6480ab71d2123cf38a7.

Requested by Russell King.
---

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 0e647da6a792..fbee93f536e9 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -54,12 +54,7 @@ work_pending:
 	mov	r0, sp				@ 'regs'
 	mov	r2, why				@ 'syscall'
 	bl	do_work_pending
-	tst	r0, #1
-	beq	no_work_pending
-	mov	r0, sp				@ pointer to regs
-	ldmia	r0, {r0 - r5}			@ have to reload r0 - r5
-	b	local_restart			@ ... and off we go
-
+	b	no_work_pending
 /*
  * "slow" syscall return path.  "why" tells us if this was a real syscall.
  */
@@ -407,7 +402,6 @@ ENTRY(vector_swi)
 	eor	scno, scno, #__NR_SYSCALL_BASE	@ check OS number
 #endif
 
-local_restart:
 	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
 	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
 
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index c4368c67b042..c0adc5e123be 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -568,13 +568,12 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
  * the kernel can handle, and then we build all the user-level signal handling
  * stack-frames in one go after that.
  */
-static int do_signal(struct pt_regs *regs, int syscall)
+static void do_signal(struct pt_regs *regs, int syscall)
 {
 	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
 	struct k_sigaction ka;
 	siginfo_t info;
 	int signr;
-	int restart = 0;
 
 	/*
 	 * If we were from a system call, check for system call restarting...
@@ -589,12 +588,10 @@ static int do_signal(struct pt_regs *regs, int syscall)
 		 * debugger will see the already changed PSW.
 		 */
 		switch (retval) {
-		case -ERESTART_RESTARTBLOCK:
-			restart++;
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
-			restart++;
+		case -ERESTART_RESTARTBLOCK:
 			regs->ARM_r0 = regs->ARM_ORIG_r0;
 			regs->ARM_pc = restart_addr;
 			break;
@@ -606,15 +603,13 @@ static int do_signal(struct pt_regs *regs, int syscall)
 	 * point the debugger may change all our registers ...
 	 */
 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
-	/*
-	 * Depending on the signal settings we may need to revert the
-	 * decision to restart the system call.  But skip this if a
-	 * debugger has chosen to restart at a different PC.
-	 */
-	if (regs->ARM_pc != restart_addr)
-		restart = 0;
 	if (signr > 0) {
-		if (unlikely(restart)) {
+		/*
+		 * Depending on the signal settings we may need to revert the
+		 * decision to restart the system call.  But skip this if a
+		 * debugger has chosen to restart at a different PC.
+		 */
+		if (regs->ARM_pc == restart_addr) {
 			if (retval == -ERESTARTNOHAND ||
 			    retval == -ERESTART_RESTARTBLOCK
 			    || (retval == -ERESTARTSYS
@@ -622,23 +617,28 @@ static int do_signal(struct pt_regs *regs, int syscall)
 				regs->ARM_r0 = -EINTR;
 				regs->ARM_pc = continue_addr;
 			}
+			clear_thread_flag(TIF_SYSCALL_RESTARTSYS);
 		}
 
 		handle_signal(signr, &ka, &info, regs);
-		return 0;
+		return;
 	}
 
-	if (unlikely(restart)) {
-		if (restart > 1)
+	if (syscall) {
+		/*
+		 * Handle restarting a different system call.  As above,
+		 * if a debugger has chosen to restart at a different PC,
+		 * ignore the restart.
+		 */
+		if (retval == -ERESTART_RESTARTBLOCK
+		    && regs->ARM_pc == restart_addr)
 			set_thread_flag(TIF_SYSCALL_RESTARTSYS);
-		regs->ARM_pc = continue_addr;
 	}
 
 	restore_saved_sigmask();
-	return restart;
 }
 
-asmlinkage int
+asmlinkage void
 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 {
 	do {
@@ -646,17 +646,10 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 			schedule();
 		} else {
 			if (unlikely(!user_mode(regs)))
-				return 0;
+				return;
 			local_irq_enable();
 			if (thread_flags & _TIF_SIGPENDING) {
-				if (unlikely(do_signal(regs, syscall))) {
-					/*
-					 * Restart without handlers.
-					 * Deal with it without leaving
-					 * the kernel space.
-					 */
-					return 1;
-				}
+				do_signal(regs, syscall);
 				syscall = 0;
 			} else {
 				clear_thread_flag(TIF_NOTIFY_RESUME);
@@ -666,5 +659,4 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 		local_irq_disable();
 		thread_flags = current_thread_info()->flags;
 	} while (thread_flags & _TIF_WORK_MASK);
-	return 0;
 }