[PATCH 2/2] x86 TS_RESTORE_SIGMASK

From: Roland McGrath
Date: Fri Mar 28 2008 - 23:16:03 EST

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@xxxxxxxxxx>
---
arch/x86/ia32/ia32_signal.c | 2 +-
arch/x86/kernel/signal_32.c | 19 ++++++++++---------
arch/x86/kernel/signal_64.c | 16 +++++++++-------
include/asm-x86/thread_info_32.h | 13 +++++++++++--
include/asm-x86/thread_info_64.h | 13 +++++++++++--
5 files changed, 42 insertions(+), 21 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 101b4b8..b7a531f 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 a06fa55..f8fbc20 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -45,7 +45,7 @@ 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;
}

@@ -591,7 +591,7 @@ 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;
@@ -608,12 +608,13 @@ 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 */
- 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;
}

return;
@@ -639,8 +640,8 @@ 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);
}
}
@@ -660,7 +661,7 @@ void do_notify_resume(struct pt_regs *regs, void *_unused,
}

/* 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 016413b..fc97dec 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -443,7 +443,7 @@ 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;
@@ -460,11 +460,13 @@ 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;
}
@@ -490,8 +492,8 @@ 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);
}
}
@@ -517,7 +519,7 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
#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 5bd5082..4c4fd4e 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)
@@ -186,9 +184,20 @@ static inline struct thread_info *current_thread_info(void)
*/
#define TS_USEDFPU 0x0001 /* FPU was used by this task 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 6c9b214..ead94d5 100644
--- a/include/asm-x86/thread_info_64.h
+++ b/include/asm-x86/thread_info_64.h
@@ -110,7 +110,6 @@ 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)
@@ -174,9 +172,20 @@ static inline struct thread_info *stack_thread_info(void)
#define TS_USEDFPU 0x0001 /* FPU was used by this task this quantum (SMP) */
#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 */
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