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>

5 files changed, 44 insertions, 23 deletions

diff --git a/arch/sh/include/asm/thread_info.h b/arch/sh/include/asm/thread_info.h
index bdeb9d46d17d..23eeed89467a 100644
--- a/arch/sh/include/asm/thread_info.h
+++ b/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 */
diff --git a/arch/sh/kernel/cpu/sh5/entry.S b/arch/sh/kernel/cpu/sh5/entry.S
index b0aacf675258..8f13f73cb2cb 100644
--- a/arch/sh/kernel/cpu/sh5/entry.S
+++ b/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
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index 3eb84931d2aa..f0abd58c3a69 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/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
diff --git a/arch/sh/kernel/signal_32.c b/arch/sh/kernel/signal_32.c
index 3db37425210d..12815ce01ecd 100644
--- a/arch/sh/kernel/signal_32.c
+++ b/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);
         }
 }
diff --git a/arch/sh/kernel/signal_64.c b/arch/sh/kernel/signal_64.c
index 74793c80a57a..feb3dddd3192 100644
--- a/arch/sh/kernel/signal_64.c
+++ b/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