signals: x86 TS_RESTORE_SIGMASK

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.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 17 insertions, 16 deletions

diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index 8e05e7f7bd4..d9237363096 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -57,7 +57,7 @@ sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 
         current->state = TASK_INTERRUPTIBLE;
         schedule();
-        set_thread_flag(TIF_RESTORE_SIGMASK);
+        set_restore_sigmask();
 
         return -ERESTARTNOHAND;
 }
@@ -593,7 +593,7 @@ static void do_signal(struct pt_regs *regs)
         if (!user_mode(regs))
                 return;
 
-        if (test_thread_flag(TIF_RESTORE_SIGMASK))
+        if (current_thread_info()->status & TS_RESTORE_SIGMASK)
                 oldset = &current->saved_sigmask;
         else
                 oldset = &current->blocked;
@@ -612,13 +612,12 @@ static void do_signal(struct pt_regs *regs)
                 /* Whee! Actually deliver the signal.  */
                 if (handle_signal(signr, &info, &ka, oldset, regs) == 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
+                         * 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;
                 }
                 return;
         }
@@ -645,8 +644,8 @@ static void do_signal(struct pt_regs *regs)
          * 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 (current_thread_info()->status & TS_RESTORE_SIGMASK) {
+                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
         }
 }
@@ -665,7 +664,7 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
         }
 
         /* deal with pending signal delivery */
-        if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
+        if (thread_info_flags & _TIF_SIGPENDING)
                 do_signal(regs);
 
         if (thread_info_flags & _TIF_HRTICK_RESCHED)
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index ccb2a4560c2..e53b267662e 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -427,7 +427,7 @@ static void do_signal(struct pt_regs *regs)
         if (!user_mode(regs))
                 return;
 
-        if (test_thread_flag(TIF_RESTORE_SIGMASK))
+        if (current_thread_info()->status & TS_RESTORE_SIGMASK)
                 oldset = &current->saved_sigmask;
         else
                 oldset = &current->blocked;
@@ -444,11 +444,13 @@ static void do_signal(struct pt_regs *regs)
 
                 /* Whee!  Actually deliver the signal.  */
                 if (handle_signal(signr, &info, &ka, oldset, regs) == 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 */
-                        clear_thread_flag(TIF_RESTORE_SIGMASK);
+                         * clear the TS_RESTORE_SIGMASK flag.
+                         */
+                        current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
                 }
                 return;
         }
@@ -476,8 +478,8 @@ static void do_signal(struct pt_regs *regs)
          * 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 (current_thread_info()->status & TS_RESTORE_SIGMASK) {
+                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
         }
 }
@@ -498,7 +500,7 @@ void do_notify_resume(struct pt_regs *regs, void *unused,
 #endif /* CONFIG_X86_MCE */
 
         /* deal with pending signal delivery */
-        if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
+        if (thread_info_flags & _TIF_SIGPENDING)
                 do_signal(regs);
 
         if (thread_info_flags & _TIF_HRTICK_RESCHED)