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>

5 files changed, 40 insertions, 21 deletions

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index bbed3a26ce55..cb3856a18c85 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -128,7 +128,7 @@ asmlinkage long sys32_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;
 }
 
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index 8e05e7f7bd40..d92373630963 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 ccb2a4560c2d..e53b267662e7 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)
diff --git a/include/asm-x86/thread_info_32.h b/include/asm-x86/thread_info_32.h
index 531859962096..b6338829d1a8 100644
--- a/include/asm-x86/thread_info_32.h
+++ b/include/asm-x86/thread_info_32.h
@@ -131,7 +131,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_EMU         5       /* syscall emulation active */
 #define TIF_SYSCALL_AUDIT       6       /* syscall auditing active */
 #define TIF_SECCOMP             7       /* secure computing */
-#define TIF_RESTORE_SIGMASK     8       /* restore signal mask in do_signal() */
 #define TIF_HRTICK_RESCHED      9       /* reprogram hrtick timer */
 #define TIF_MEMDIE              16
 #define TIF_DEBUG               17      /* uses debug registers */
@@ -151,7 +150,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
-#define _TIF_RESTORE_SIGMASK    (1 << TIF_RESTORE_SIGMASK)
 #define _TIF_HRTICK_RESCHED     (1 << TIF_HRTICK_RESCHED)
 #define _TIF_DEBUG              (1 << TIF_DEBUG)
 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
@@ -188,9 +186,20 @@ static inline struct thread_info *current_thread_info(void)
                                            this quantum (SMP) */
 #define TS_POLLING              0x0002  /* True if in idle loop
                                            and not sleeping */
+#define TS_RESTORE_SIGMASK      0x0004  /* restore signal mask in do_signal() */
 
 #define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
 
+#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, &ti->flags);
+}
+#endif  /* !__ASSEMBLY__ */
+
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_THREAD_INFO_H */
diff --git a/include/asm-x86/thread_info_64.h b/include/asm-x86/thread_info_64.h
index ed664e874dec..cb69f70abba1 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -109,7 +109,6 @@ static inline struct thread_info *stack_thread_info(void)
 #define TIF_IRET                5       /* force IRET */
 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 #define TIF_SECCOMP             8       /* secure computing */
-#define TIF_RESTORE_SIGMASK     9       /* restore signal mask in do_signal */
 #define TIF_MCE_NOTIFY          10      /* notify userspace of an MCE */
 #define TIF_HRTICK_RESCHED      11      /* reprogram hrtick timer */
 /* 16 free */
@@ -133,7 +132,6 @@ static inline struct thread_info *stack_thread_info(void)
 #define _TIF_IRET               (1 << TIF_IRET)
 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
-#define _TIF_RESTORE_SIGMASK    (1 << TIF_RESTORE_SIGMASK)
 #define _TIF_MCE_NOTIFY         (1 << TIF_MCE_NOTIFY)
 #define _TIF_HRTICK_RESCHED     (1 << TIF_HRTICK_RESCHED)
 #define _TIF_IA32               (1 << TIF_IA32)
@@ -178,9 +176,20 @@ static inline struct thread_info *stack_thread_info(void)
 #define TS_COMPAT               0x0002  /* 32bit syscall active */
 #define TS_POLLING              0x0004  /* true if in idle loop
                                            and not sleeping */
+#define TS_RESTORE_SIGMASK      0x0008  /* restore signal mask in do_signal() */
 
 #define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
 
+#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, &ti->flags);
+}
+#endif  /* !__ASSEMBLY__ */
+
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_THREAD_INFO_H */