[PATCH] convert signal handling of NODEFER to act like other Unix boxes.

It has been reported that the way Linux handles NODEFER for signals is
not consistent with the way other Unix boxes handle it.  I've written a
program to test the behavior of how this flag affects signals and had
several reports from people who ran this on various Unix boxes,
confirming that Linux seems to be unique on the way this is handled.

The way NODEFER affects signals on other Unix boxes is as follows:

1) If NODEFER is set, other signals in sa_mask are still blocked.

2) If NODEFER is set and the signal is in sa_mask, then the signal is
still blocked. (Note: this is the behavior of all tested but Linux _and_
NetBSD 2.0 *).

The way NODEFER affects signals on Linux:

1) If NODEFER is set, other signals are _not_ blocked regardless of
sa_mask (Even NetBSD doesn't do this).

2) If NODEFER is set and the signal is in sa_mask, then the signal being
handled is not blocked.

The patch converts signal handling in all current Linux architectures to
the way most Unix boxes work.

Unix boxes that were tested:  DU4, AIX 5.2, Irix 6.5, NetBSD 2.0, SFU
3.5 on WinXP, AIX 5.3, Mac OSX, and of course Linux 2.6.13-rcX.

* NetBSD was the only other Unix to behave like Linux on point #2. The
main concern was brought up by point #1 which even NetBSD isn't like
Linux.  So with this patch, we leave NetBSD as the lonely one that
behaves differently here with #2.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/alpha/kernel/signal.c

@@ -566,14 +566,13 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
 	if (ka->sa.sa_flags & SA_RESETHAND)
 		ka->sa.sa_handler = SIG_DFL;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER)) 
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 static inline void
 syscall_restart(unsigned long r0, unsigned long r19,

arch/arm/kernel/signal.c

@@ -658,10 +658,11 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	/*
 	 * Block the signal if we were unsuccessful.
 	 */
-	if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
+	if (ret != 0) {
 		spin_lock_irq(&tsk->sighand->siglock);
 		sigorsets(&tsk->blocked, &tsk->blocked,
 			  &ka->sa.sa_mask);
+		if (!(ka->sa.sa_flags & SA_NODEFER))
 			sigaddset(&tsk->blocked, sig);
 		recalc_sigpending();
 		spin_unlock_irq(&tsk->sighand->siglock);

arch/arm26/kernel/signal.c

@@ -454,14 +454,13 @@ handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 		if (ka->sa.sa_flags & SA_ONESHOT)
 			ka->sa.sa_handler = SIG_DFL;
 
-		if (!(ka->sa.sa_flags & SA_NODEFER)) {
 		spin_lock_irq(&tsk->sighand->siglock);
 		sigorsets(&tsk->blocked, &tsk->blocked,
 			  &ka->sa.sa_mask);
+		if (!(ka->sa.sa_flags & SA_NODEFER))
 			sigaddset(&tsk->blocked, sig);
 		recalc_sigpending();
 		spin_unlock_irq(&tsk->sighand->siglock);
-		}
 		return;
 	}
 

arch/cris/arch-v10/kernel/signal.c

@@ -517,14 +517,13 @@ handle_signal(int canrestart, unsigned long sig,
 	if (ka->sa.sa_flags & SA_ONESHOT)
 		ka->sa.sa_handler = SIG_DFL;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/cris/arch-v32/kernel/signal.c

@@ -568,14 +568,13 @@ handle_signal(int canrestart, unsigned long sig,
 	if (ka->sa.sa_flags & SA_ONESHOT)
 		ka->sa.sa_handler = SIG_DFL;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/frv/kernel/signal.c

@@ -506,13 +506,12 @@ static void handle_signal(unsigned long sig, siginfo_t *info,
 	else
 		setup_frame(sig, ka, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked, sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
-	}
 } /* end handle_signal() */
 
 /*****************************************************************************/

arch/h8300/kernel/signal.c

@@ -488,14 +488,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	else
 		setup_frame(sig, ka, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/i386/kernel/signal.c

@@ -577,9 +577,10 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	else
 		ret = setup_frame(sig, ka, oldset, regs);
 
-	if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
+	if (ret) {
 		spin_lock_irq(&current->sighand->siglock);
 		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+		if (!(ka->sa.sa_flags & SA_NODEFER))
 			sigaddset(&current->blocked,sig);
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);

arch/ia64/kernel/signal.c

@@ -467,15 +467,12 @@ handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigse
 		if (!setup_frame(sig, ka, info, oldset, scr))
 			return 0;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
-		{
 	sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked, sig);
 	recalc_sigpending();
-		}
 	spin_unlock_irq(&current->sighand->siglock);
-	}
 	return 1;
 }
 

arch/m32r/kernel/signal.c

@@ -341,14 +341,13 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 	/* Set up the stack frame */
 	setup_rt_frame(sig, ka, info, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/m68knommu/kernel/signal.c

@@ -732,14 +732,13 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
 	if (ka->sa.sa_flags & SA_ONESHOT)
 		ka->sa.sa_handler = SIG_DFL;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/mips/kernel/irixsig.c

@@ -155,14 +155,13 @@ static inline void handle_signal(unsigned long sig, siginfo_t *info,
 	else
 		setup_irix_frame(ka, regs, sig, oldset);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 asmlinkage int do_irix_signal(sigset_t *oldset, struct pt_regs *regs)
 {

arch/mips/kernel/signal.c

@@ -425,14 +425,13 @@ static inline void handle_signal(unsigned long sig, siginfo_t *info,
 		setup_frame(ka, regs, sig, oldset);
 #endif
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
 extern int do_irix_signal(sigset_t *oldset, struct pt_regs *regs);

arch/mips/kernel/signal32.c

@@ -751,14 +751,13 @@ static inline void handle_signal(unsigned long sig, siginfo_t *info,
 	else
 		setup_frame(ka, regs, sig, oldset);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 int do_signal32(sigset_t *oldset, struct pt_regs *regs)
 {

arch/parisc/kernel/signal.c

@@ -517,13 +517,12 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	if (!setup_rt_frame(sig, ka, info, oldset, regs, in_syscall))
 		return 0;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
-	}
 	return 1;
 }
 

arch/ppc/kernel/signal.c

@@ -759,13 +759,12 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 	else
 		handle_signal(signr, &ka, &info, oldset, regs, newsp);
 
-	if (!(ka.sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka.sa.sa_mask);
+	if (!(ka.sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked, signr);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
-	}
 
 	return 1;
 }

arch/ppc64/kernel/signal.c

@@ -481,9 +481,10 @@ static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 	/* Set up Signal Frame */
 	ret = setup_rt_frame(sig, ka, info, oldset, regs);
 
-	if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
+	if (ret) {
 		spin_lock_irq(&current->sighand->siglock);
 		sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
+		if (!(ka->sa.sa_flags & SA_NODEFER))
 			sigaddset(&current->blocked,sig);
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);

arch/ppc64/kernel/signal32.c

@@ -976,10 +976,11 @@ int do_signal32(sigset_t *oldset, struct pt_regs *regs)
 	else
 		ret = handle_signal32(signr, &ka, &info, oldset, regs, newsp);
 
-	if (ret && !(ka.sa.sa_flags & SA_NODEFER)) {
+	if (ret) {
 		spin_lock_irq(&current->sighand->siglock);
 		sigorsets(&current->blocked, &current->blocked,
 			  &ka.sa.sa_mask);
+		if (!(ka.sa.sa_flags & SA_NODEFER))
 			sigaddset(&current->blocked, signr);
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);

arch/s390/kernel/compat_signal.c

@@ -637,12 +637,11 @@ handle_signal32(unsigned long sig, struct k_sigaction *ka,
 	else
 		setup_frame32(sig, ka, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 

arch/s390/kernel/signal.c

@@ -429,14 +429,13 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	else
 		setup_frame(sig, ka, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/sh/kernel/signal.c

@@ -546,14 +546,13 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 	if (ka->sa.sa_flags & SA_ONESHOT)
 		ka->sa.sa_handler = SIG_DFL;
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/sh64/kernel/signal.c

@@ -664,14 +664,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	else
 		setup_frame(sig, ka, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/sparc/kernel/signal.c

@@ -1034,14 +1034,13 @@ handle_signal(unsigned long signr, struct k_sigaction *ka,
 		else
 			setup_frame(&ka->sa, regs, signr, oldset, info);
 	}
-	if (!(ka->sa.sa_flags & SA_NOMASK)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NOMASK))
 		sigaddset(&current->blocked, signr);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 				   struct sigaction *sa)

arch/sparc64/kernel/signal.c

@@ -574,14 +574,13 @@ static inline void handle_signal(unsigned long signr, struct k_sigaction *ka,
 {
 	setup_rt_frame(ka, regs, signr, oldset,
 		       (ka->sa.sa_flags & SA_SIGINFO) ? info : NULL);
-	if (!(ka->sa.sa_flags & SA_NOMASK)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NOMASK))
 		sigaddset(&current->blocked,signr);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 				     struct sigaction *sa)

arch/sparc64/kernel/signal32.c

@@ -1325,14 +1325,13 @@ static inline void handle_signal32(unsigned long signr, struct k_sigaction *ka,
 		else
 			setup_frame32(&ka->sa, regs, signr, oldset, info);
 	}
-	if (!(ka->sa.sa_flags & SA_NOMASK)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NOMASK))
 		sigaddset(&current->blocked,signr);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 static inline void syscall_restart32(unsigned long orig_i0, struct pt_regs *regs,
 				     struct sigaction *sa)

arch/um/kernel/signal_kern.c

@@ -87,11 +87,11 @@ static int handle_signal(struct pt_regs *regs, unsigned long signr,
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);
 		force_sigsegv(signr, current);
-	}
-	else if(!(ka->sa.sa_flags & SA_NODEFER)){
+	} else {
 		spin_lock_irq(&current->sighand->siglock);
 		sigorsets(&current->blocked, &current->blocked, 
 			  &ka->sa.sa_mask);
+		 if(!(ka->sa.sa_flags & SA_NODEFER))
 			sigaddset(&current->blocked, signr);
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);

arch/v850/kernel/signal.c

@@ -462,14 +462,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	else
 		setup_frame(sig, ka, oldset, regs);
 
-	if (!(ka->sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked,sig);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 }
-}
 
 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't

arch/x86_64/kernel/signal.c

@@ -394,9 +394,10 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 #endif
 	ret = setup_rt_frame(sig, ka, info, oldset, regs);
 
-	if (ret && !(ka->sa.sa_flags & SA_NODEFER)) {
+	if (ret) {
 		spin_lock_irq(&current->sighand->siglock);
 		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+		if (!(ka->sa.sa_flags & SA_NODEFER))
 			sigaddset(&current->blocked,sig);
 		recalc_sigpending();
 		spin_unlock_irq(&current->sighand->siglock);

arch/xtensa/kernel/signal.c

@@ -702,12 +702,11 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (ka.sa.sa_flags & SA_ONESHOT)
 		ka.sa.sa_handler = SIG_DFL;
 
-	if (!(ka.sa.sa_flags & SA_NODEFER)) {
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked, &current->blocked, &ka.sa.sa_mask);
+	if (!(ka.sa.sa_flags & SA_NODEFER))
 		sigaddset(&current->blocked, signr);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
-	}
 	return 1;
 }