sh: TS_RESTORE_SIGMASK conversion.

Replace TIF_RESTORE_SIGMASK with TS_RESTORE_SIGMASK and define our own
set_restore_sigmask() function.  This saves the costly SMP-safe set_bit
operation, which we do not need for the sigmask flag since TIF_SIGPENDING
always has to be set too.

Based on the x86 and powerpc change.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/thread_info.h

@@ -19,6 +19,7 @@ struct thread_info {
 	struct task_struct	*task;		/* main task structure */
 	struct exec_domain	*exec_domain;	/* execution domain */
 	unsigned long		flags;		/* low level flags */
+	__u32			status;		/* thread synchronous flags */
 	__u32			cpu;
 	int			preempt_count; /* 0 => preemptable, <0 => BUG */
 	mm_segment_t		addr_limit;	/* thread address space */
@@ -111,7 +112,6 @@ extern void free_thread_info(struct thread_info *ti);
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_SIGPENDING		1	/* signal pending */
 #define TIF_NEED_RESCHED	2	/* rescheduling necessary */
-#define TIF_RESTORE_SIGMASK	3	/* restore signal mask in do_signal() */
 #define TIF_SINGLESTEP		4	/* singlestepping active */
 #define TIF_SYSCALL_AUDIT	5	/* syscall auditing active */
 #define TIF_SECCOMP		6	/* secure computing */
@@ -125,7 +125,6 @@ extern void free_thread_info(struct thread_info *ti);
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
-#define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
@@ -149,13 +148,32 @@ extern void free_thread_info(struct thread_info *ti);
 /* work to do on any return to u-space */
 #define _TIF_ALLWORK_MASK	(_TIF_SYSCALL_TRACE | _TIF_SIGPENDING      | \
 				 _TIF_NEED_RESCHED  | _TIF_SYSCALL_AUDIT   | \
-				 _TIF_SINGLESTEP    | _TIF_RESTORE_SIGMASK | \
-				 _TIF_NOTIFY_RESUME | _TIF_SYSCALL_TRACEPOINT)
+				 _TIF_SINGLESTEP    | _TIF_NOTIFY_RESUME   | \
+				 _TIF_SYSCALL_TRACEPOINT)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		(_TIF_ALLWORK_MASK & ~(_TIF_SYSCALL_TRACE | \
 				 _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP))
 
+/*
+ * Thread-synchronous status.
+ *
+ * This is different from the flags in that nobody else
+ * ever touches our thread-synchronous status, so we don't
+ * have to worry about atomic accesses.
+ */
+#define TS_RESTORE_SIGMASK	0x0001	/* restore signal mask in do_signal() */
+
+#ifndef __ASSEMBLY__
+#define HAVE_SET_RESTORE_SIGMASK	1
+static inline void set_restore_sigmask(void)
+{
+	struct thread_info *ti = current_thread_info();
+	ti->status |= TS_RESTORE_SIGMASK;
+	set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
+}
+#endif	/* !__ASSEMBLY__ */
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASM_SH_THREAD_INFO_H */

arch/sh/kernel/cpu/sh5/entry.S

@@ -933,7 +933,7 @@ ret_with_reschedule:
 
 	pta	restore_all, tr1
 
-	movi	(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r8
+	movi	_TIF_SIGPENDING, r8
 	and	r8, r7, r8
 	pta	work_notifysig, tr0
 	bne	r8, ZERO, tr0

arch/sh/kernel/entry-common.S

@@ -133,7 +133,7 @@ work_pending:
 	! r8: current_thread_info
 	! t:  result of "tst	#_TIF_NEED_RESCHED, r0"
 	bf/s	work_resched
-	 tst	#(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0
+	 tst	#_TIF_SIGPENDING, r0
 work_notifysig:
 	bt/s	__restore_all
 	 mov	r15, r4

arch/sh/kernel/signal_32.c

@@ -67,7 +67,8 @@ sys_sigsuspend(old_sigset_t mask,
 
 	current->state = TASK_INTERRUPTIBLE;
 	schedule();
-	set_thread_flag(TIF_RESTORE_SIGMASK);
+	set_restore_sigmask();
+
 	return -ERESTARTNOHAND;
 }
 
@@ -590,7 +591,7 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 	if (try_to_freeze())
 		goto no_signal;
 
-	if (test_thread_flag(TIF_RESTORE_SIGMASK))
+	if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 		oldset = &current->saved_sigmask;
 	else
 		oldset = &current->blocked;
@@ -602,12 +603,13 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 		/* Whee!  Actually deliver the signal.  */
 		if (handle_signal(signr, &ka, &info, oldset,
 				  regs, save_r0) == 0) {
-			/* a signal was successfully delivered; the saved
+			/*
+			 * 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);
+			 * clear the TS_RESTORE_SIGMASK flag
+			 */
+			current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 
 			tracehook_signal_handler(signr, &info, &ka, regs,
 					test_thread_flag(TIF_SINGLESTEP));
@@ -631,10 +633,12 @@ no_signal:
 		}
 	}
 
-	/* if there's no signal to deliver, we just put the saved sigmask
-	 * back */
-	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
-		clear_thread_flag(TIF_RESTORE_SIGMASK);
+	/*
+	 * If there's no signal to deliver, we just put the saved sigmask
+	 * back.
+	 */
+	if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
+		current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 	}
 }

arch/sh/kernel/signal_64.c

@@ -101,7 +101,7 @@ static int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (try_to_freeze())
 		goto no_signal;
 
-	if (test_thread_flag(TIF_RESTORE_SIGMASK))
+	if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 		oldset = &current->saved_sigmask;
 	else if (!oldset)
 		oldset = &current->blocked;
@@ -115,11 +115,9 @@ static int do_signal(struct pt_regs *regs, sigset_t *oldset)
 			/*
 			 * If a signal was successfully delivered, the
 			 * saved sigmask is in its frame, and we can
-			 * clear the TIF_RESTORE_SIGMASK flag.
+			 * clear the TS_RESTORE_SIGMASK flag.
 			 */
-			if (test_thread_flag(TIF_RESTORE_SIGMASK))
-				clear_thread_flag(TIF_RESTORE_SIGMASK);
-
+			current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 			tracehook_signal_handler(signr, &info, &ka, regs, 0);
 			return 1;
 		}
@@ -146,8 +144,8 @@ no_signal:
 	}
 
 	/* No signal to deliver -- put the saved sigmask back */
-	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
-		clear_thread_flag(TIF_RESTORE_SIGMASK);
+	if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
+		current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 	}
 
@@ -176,6 +174,7 @@ sys_sigsuspend(old_sigset_t mask,
 	while (1) {
 		current->state = TASK_INTERRUPTIBLE;
 		schedule();
+		set_restore_sigmask();
 		regs->pc += 4;    /* because sys_sigreturn decrements the pc */
 		if (do_signal(regs, &saveset)) {
 			/* pc now points at signal handler. Need to decrement