[PATCH 1/3] UML - Add TIF_RESTORE_SIGMASK support

[Jeff Dike <jdike@addtoit.com>]

Add support for TIF_RESTORE_SIGMASK.  I copy the i386 handling of the flag.
sys_sigsuspend is also changed to follow i386.
Also a bit of cleanup -
   turn an if into a switch
   get rid of a couple more emacs formatting comments

Signed-off-by: Jeff Dike <jdike@addtoit.com>

Index: linux-2.6.15-mm/arch/um/kernel/signal_kern.c
===================================================================
--- linux-2.6.15-mm.orig/arch/um/kernel/signal_kern.c	2006-01-14 18:50:04.000000000 -0500
+++ linux-2.6.15-mm/arch/um/kernel/signal_kern.c	2006-01-14 18:56:57.000000000 -0500
@@ -99,31 +99,46 @@ static int handle_signal(struct pt_regs 
 	return err;
 }
 
-static int kern_do_signal(struct pt_regs *regs, sigset_t *oldset)
+static int kern_do_signal(struct pt_regs *regs)
 {
 	struct k_sigaction ka_copy;
 	siginfo_t info;
+	sigset_t *oldset;
 	int sig, handled_sig = 0;
 
+	if (test_thread_flag(TIF_RESTORE_SIGMASK))
+		oldset = &current->saved_sigmask;
+	else
+		oldset = &current->blocked;
+
 	while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){
 		handled_sig = 1;
 		/* Whee!  Actually deliver the signal.  */
-		if(!handle_signal(regs, sig, &ka_copy, &info, oldset))
+		if(!handle_signal(regs, sig, &ka_copy, &info, oldset)){
+			/* a signal was successfully delivered; the saved
+			 * sigmask will have been stored in the signal frame,
+			 * and will be restored by sigreturn, so we can simply
+			 * clear the TIF_RESTORE_SIGMASK flag */
+			if (test_thread_flag(TIF_RESTORE_SIGMASK))
+				clear_thread_flag(TIF_RESTORE_SIGMASK);
 			break;
+		}
 	}
 
 	/* Did we come from a system call? */
 	if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){
 		/* Restart the system call - no handlers present */
-		if(PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOHAND ||
-		   PT_REGS_SYSCALL_RET(regs) == -ERESTARTSYS ||
-		   PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOINTR){
+		switch(PT_REGS_SYSCALL_RET(regs)){
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
 			PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 			PT_REGS_RESTART_SYSCALL(regs);
-		}
-		else if(PT_REGS_SYSCALL_RET(regs) == -ERESTART_RESTARTBLOCK){
+			break;
+		case -ERESTART_RESTARTBLOCK:
 			PT_REGS_SYSCALL_RET(regs) = __NR_restart_syscall;
 			PT_REGS_RESTART_SYSCALL(regs);
+			break;
  		}
 	}
 
@@ -137,12 +152,19 @@ static int kern_do_signal(struct pt_regs
 	if(current->ptrace & PT_DTRACE)
 		current->thread.singlestep_syscall =
 			is_syscall(PT_REGS_IP(&current->thread.regs));
+
+	/* if there's no signal to deliver, we just put the saved sigmask
+	 * back */
+	if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
+		clear_thread_flag(TIF_RESTORE_SIGMASK);
+		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+	}
 	return(handled_sig);
 }
 
 int do_signal(void)
 {
-	return(kern_do_signal(&current->thread.regs, &current->blocked));
+	return(kern_do_signal(&current->thread.regs));
 }
 
 /*
@@ -150,27 +172,22 @@ int do_signal(void)
  */
 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 {
-	sigset_t saveset;
-
 	mask &= _BLOCKABLE;
 	spin_lock_irq(&current->sighand->siglock);
-	saveset = current->blocked;
+	current->saved_sigmask = current->blocked;
 	siginitset(&current->blocked, mask);
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 
-	PT_REGS_SYSCALL_RET(&current->thread.regs) = -EINTR;
-	while (1) {
-		current->state = TASK_INTERRUPTIBLE;
-		schedule();
-		if(kern_do_signal(&current->thread.regs, &saveset))
-			return(-EINTR);
-	}
+	current->state = TASK_INTERRUPTIBLE;
+	schedule();
+	set_thread_flag(TIF_RESTORE_SIGMASK);
+	return -ERESTARTNOHAND;
 }
 
 long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
 {
-	sigset_t saveset, newset;
+	sigset_t newset;
 
 	/* XXX: Don't preclude handling different sized sigset_t's.  */
 	if (sigsetsize != sizeof(sigset_t))
@@ -181,32 +198,18 @@ long sys_rt_sigsuspend(sigset_t __user *
 	sigdelsetmask(&newset, ~_BLOCKABLE);
 
 	spin_lock_irq(&current->sighand->siglock);
-	saveset = current->blocked;
+	current->saved_sigmask = current->blocked;
 	current->blocked = newset;
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 
-	PT_REGS_SYSCALL_RET(&current->thread.regs) = -EINTR;
-	while (1) {
-		current->state = TASK_INTERRUPTIBLE;
-		schedule();
-		if (kern_do_signal(&current->thread.regs, &saveset))
-			return(-EINTR);
-	}
+	current->state = TASK_INTERRUPTIBLE;
+	schedule();
+	set_thread_flag(TIF_RESTORE_SIGMASK);
+	return -ERESTARTNOHAND;
 }
 
 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 {
 	return(do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs)));
 }
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
Index: linux-2.6.15-mm/include/asm-um/thread_info.h
===================================================================
--- linux-2.6.15-mm.orig/include/asm-um/thread_info.h	2006-01-14 18:14:20.000000000 -0500
+++ linux-2.6.15-mm/include/asm-um/thread_info.h	2006-01-14 18:58:15.000000000 -0500
@@ -69,6 +69,7 @@ static inline struct thread_info *curren
 #define TIF_RESTART_BLOCK 	4
 #define TIF_MEMDIE	 	5
 #define TIF_SYSCALL_AUDIT	6
+#define TIF_RESTORE_SIGMASK	7
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
@@ -76,16 +77,6 @@ static inline struct thread_info *curren
 #define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
 #define _TIF_MEMDIE		(1 << TIF_MEMDIE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
+#define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 
 #endif
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */