__set_current_blocked already has a test to see if the new
value and the old value of the signal mask differ.  Both
real_blocked and blocked should be on the same cache line,
and are a single word compare on 64bit.

Historically real_blocked or saved_sigmask could be garbage
so a test had to be used that always tested valid bits.
Now that real_blocked is alwasy valid there is no need
to test something different.

Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
---
 arch/arc/include/asm/thread_info.h       |  1 -
 arch/arm/include/asm/thread_info.h       |  1 -
 arch/arm64/include/asm/thread_info.h     |  1 -
 arch/c6x/include/asm/thread_info.h       |  1 -
 arch/csky/include/asm/thread_info.h      |  2 -
 arch/h8300/include/asm/thread_info.h     |  1 -
 arch/hexagon/include/asm/thread_info.h   |  1 -
 arch/m68k/include/asm/thread_info.h      |  1 -
 arch/mips/include/asm/thread_info.h      |  1 -
 arch/nds32/include/asm/thread_info.h     |  2 -
 arch/nios2/include/asm/thread_info.h     |  2 -
 arch/riscv/include/asm/thread_info.h     |  1 -
 arch/s390/include/asm/thread_info.h      |  1 -
 arch/sparc/include/asm/thread_info_32.h  |  1 -
 arch/um/include/asm/thread_info.h        |  1 -
 arch/unicore32/include/asm/thread_info.h |  1 -
 arch/xtensa/include/asm/thread_info.h    |  1 -
 include/linux/sched.h                    |  3 -
 include/linux/sched/signal.h             | 79 +-----------------------
 kernel/ptrace.c                          |  2 -
 kernel/signal.c                          |  7 ---
 21 files changed, 1 insertion(+), 110 deletions(-)

diff --git a/arch/arc/include/asm/thread_info.h 
b/arch/arc/include/asm/thread_info.h
index c85947bac5e5..bde0f76a986b 100644
--- a/arch/arc/include/asm/thread_info.h
+++ b/arch/arc/include/asm/thread_info.h
@@ -77,7 +77,6 @@ static inline __attribute_const__ struct thread_info 
*current_thread_info(void)
  * - pending work-to-be-done flags are in LSW
  * - other flags in MSW
  */
-#define TIF_RESTORE_SIGMASK    0       /* restore sig mask in do_signal() */
 #define TIF_NOTIFY_RESUME      1       /* resumption notification requested */
 #define TIF_SIGPENDING         2       /* signal pending */
 #define TIF_NEED_RESCHED       3       /* rescheduling necessary */
diff --git a/arch/arm/include/asm/thread_info.h 
b/arch/arm/include/asm/thread_info.h
index 286eb61c632b..d1ee97031c21 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -147,7 +147,6 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
 #define TIF_NOHZ               12      /* in adaptive nohz mode */
 #define TIF_USING_IWMMXT       17
 #define TIF_MEMDIE             18      /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK    20
 
 #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
diff --git a/arch/arm64/include/asm/thread_info.h 
b/arch/arm64/include/asm/thread_info.h
index eb3ef73e07cf..bb8fdc9f78d2 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -93,7 +93,6 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define TIF_SECCOMP            11
 #define TIF_MEMDIE             18      /* is terminating due to OOM killer */
 #define TIF_FREEZE             19
-#define TIF_RESTORE_SIGMASK    20
 #define TIF_SINGLESTEP         21
 #define TIF_32BIT              22      /* 32bit process */
 #define TIF_SVE                        23      /* Scalable Vector Extension in 
use */
diff --git a/arch/c6x/include/asm/thread_info.h 
b/arch/c6x/include/asm/thread_info.h
index 59a5697fe0f3..229d365ffa9d 100644
--- a/arch/c6x/include/asm/thread_info.h
+++ b/arch/c6x/include/asm/thread_info.h
@@ -84,7 +84,6 @@ struct thread_info *current_thread_info(void)
 #define TIF_NOTIFY_RESUME      1       /* resumption notification requested */
 #define TIF_SIGPENDING         2       /* signal pending */
 #define TIF_NEED_RESCHED       3       /* rescheduling necessary */
-#define TIF_RESTORE_SIGMASK    4       /* restore signal mask in do_signal() */
 
 #define TIF_MEMDIE             17      /* OOM killer killed process */
 
diff --git a/arch/csky/include/asm/thread_info.h 
b/arch/csky/include/asm/thread_info.h
index 0b546a55a8bf..f7261865e9dc 100644
--- a/arch/csky/include/asm/thread_info.h
+++ b/arch/csky/include/asm/thread_info.h
@@ -59,7 +59,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_AUDIT      5       /* syscall auditing */
 #define TIF_POLLING_NRFLAG     16      /* poll_idle() is TIF_NEED_RESCHED */
 #define TIF_MEMDIE             18      /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK    20      /* restore signal mask in do_signal() */
 #define TIF_SECCOMP            21      /* secure computing */
 
 #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
@@ -70,7 +69,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_AUDIT     (1 << TIF_SYSCALL_AUDIT)
 #define _TIF_POLLING_NRFLAG    (1 << TIF_POLLING_NRFLAG)
 #define _TIF_MEMDIE            (1 << TIF_MEMDIE)
-#define _TIF_RESTORE_SIGMASK   (1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP           (1 << TIF_SECCOMP)
 
 #endif /* _ASM_CSKY_THREAD_INFO_H */
diff --git a/arch/h8300/include/asm/thread_info.h 
b/arch/h8300/include/asm/thread_info.h
index 0cdaa302d3d2..8d5d5063628a 100644
--- a/arch/h8300/include/asm/thread_info.h
+++ b/arch/h8300/include/asm/thread_info.h
@@ -68,7 +68,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NEED_RESCHED       2       /* rescheduling necessary */
 #define TIF_SINGLESTEP         3       /* singlestepping active */
 #define TIF_MEMDIE             4       /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK    5       /* restore signal mask in do_signal() */
 #define TIF_NOTIFY_RESUME      6       /* callback before returning to user */
 #define TIF_SYSCALL_AUDIT      7       /* syscall auditing active */
 #define TIF_SYSCALL_TRACEPOINT 8       /* for ftrace syscall instrumentation */
diff --git a/arch/hexagon/include/asm/thread_info.h 
b/arch/hexagon/include/asm/thread_info.h
index f41f9c6f0e31..2d1183690bc5 100644
--- a/arch/hexagon/include/asm/thread_info.h
+++ b/arch/hexagon/include/asm/thread_info.h
@@ -107,7 +107,6 @@ register struct thread_info *__current_thread_info 
asm(QUOTED_THREADINFO_REG);
 #define TIF_SIGPENDING          2       /* signal pending */
 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
 #define TIF_SINGLESTEP          4       /* restore ss @ return to usr mode */
-#define TIF_RESTORE_SIGMASK     6       /* restore sig mask in do_signal() */
 /* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE              17      /* OOM killer killed process */
 
diff --git a/arch/m68k/include/asm/thread_info.h 
b/arch/m68k/include/asm/thread_info.h
index 015f1ca38305..d620cb4f240e 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -66,6 +66,5 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_DELAYED_TRACE      14      /* single step a syscall */
 #define TIF_SYSCALL_TRACE      15      /* syscall trace active */
 #define TIF_MEMDIE             16      /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK    18      /* restore signal mask in do_signal */
 
 #endif /* _ASM_M68K_THREAD_INFO_H */
diff --git a/arch/mips/include/asm/thread_info.h 
b/arch/mips/include/asm/thread_info.h
index 4993db40482c..b2327b51c141 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -97,7 +97,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SECCOMP            4       /* secure computing */
 #define TIF_NOTIFY_RESUME      5       /* callback before returning to user */
 #define TIF_UPROBE             6       /* breakpointed or singlestepping */
-#define TIF_RESTORE_SIGMASK    9       /* restore signal mask in do_signal() */
 #define TIF_USEDFPU            16      /* FPU was used by this task this 
quantum (SMP) */
 #define TIF_MEMDIE             18      /* is terminating due to OOM killer */
 #define TIF_NOHZ               19      /* in adaptive nohz mode */
diff --git a/arch/nds32/include/asm/thread_info.h 
b/arch/nds32/include/asm/thread_info.h
index c135111ec44e..79914ce56cd9 100644
--- a/arch/nds32/include/asm/thread_info.h
+++ b/arch/nds32/include/asm/thread_info.h
@@ -52,7 +52,6 @@ struct thread_info {
 #define TIF_POLLING_NRFLAG     17
 #define TIF_MEMDIE             18
 #define TIF_FREEZE             19
-#define TIF_RESTORE_SIGMASK    20
 
 #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
@@ -61,7 +60,6 @@ struct thread_info {
 #define _TIF_SYSCALL_TRACE     (1 << TIF_SYSCALL_TRACE)
 #define _TIF_POLLING_NRFLAG    (1 << TIF_POLLING_NRFLAG)
 #define _TIF_FREEZE            (1 << TIF_FREEZE)
-#define _TIF_RESTORE_SIGMASK   (1 << TIF_RESTORE_SIGMASK)
 
 /*
  * Change these and you break ASM code in entry-common.S
diff --git a/arch/nios2/include/asm/thread_info.h 
b/arch/nios2/include/asm/thread_info.h
index 7349a4fa635b..b17309c3a5b3 100644
--- a/arch/nios2/include/asm/thread_info.h
+++ b/arch/nios2/include/asm/thread_info.h
@@ -86,7 +86,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE             4       /* is terminating due to OOM killer */
 #define TIF_SECCOMP            5       /* secure computing */
 #define TIF_SYSCALL_AUDIT      6       /* syscall auditing active */
-#define TIF_RESTORE_SIGMASK    9       /* restore signal mask in do_signal() */
 
 #define TIF_POLLING_NRFLAG     16      /* true if poll_idle() is polling
                                           TIF_NEED_RESCHED */
@@ -97,7 +96,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
 #define _TIF_SECCOMP           (1 << TIF_SECCOMP)
 #define _TIF_SYSCALL_AUDIT     (1 << TIF_SYSCALL_AUDIT)
-#define _TIF_RESTORE_SIGMASK   (1 << TIF_RESTORE_SIGMASK)
 #define _TIF_POLLING_NRFLAG    (1 << TIF_POLLING_NRFLAG)
 
 /* work to do on interrupt/exception return */
diff --git a/arch/riscv/include/asm/thread_info.h 
b/arch/riscv/include/asm/thread_info.h
index 9c039870019b..6a1e393b4b5f 100644
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
@@ -79,7 +79,6 @@ struct thread_info {
 #define TIF_NOTIFY_RESUME      1       /* callback before returning to user */
 #define TIF_SIGPENDING         2       /* signal pending */
 #define TIF_NEED_RESCHED       3       /* rescheduling necessary */
-#define TIF_RESTORE_SIGMASK    4       /* restore signal mask in do_signal() */
 #define TIF_MEMDIE             5       /* is terminating due to OOM killer */
 #define TIF_SYSCALL_TRACEPOINT  6       /* syscall tracepoint instrumentation 
*/
 #define TIF_SYSCALL_AUDIT      7       /* syscall auditing */
diff --git a/arch/s390/include/asm/thread_info.h 
b/arch/s390/include/asm/thread_info.h
index ce4e17c9aad6..6a1d1636016b 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -71,7 +71,6 @@ void arch_setup_new_exec(void);
 
 #define TIF_31BIT              16      /* 32bit process */
 #define TIF_MEMDIE             17      /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK    18      /* restore signal mask in do_signal() */
 #define TIF_SINGLE_STEP                19      /* This task is single stepped 
*/
 #define TIF_BLOCK_STEP         20      /* This task is block stepped */
 #define TIF_UPROBE_SINGLESTEP  21      /* This task is uprobe single stepped */
diff --git a/arch/sparc/include/asm/thread_info_32.h 
b/arch/sparc/include/asm/thread_info_32.h
index 548b366165dd..567f472c730b 100644
--- a/arch/sparc/include/asm/thread_info_32.h
+++ b/arch/sparc/include/asm/thread_info_32.h
@@ -103,7 +103,6 @@ register struct thread_info *current_thread_info_reg 
asm("g6");
 #define TIF_NOTIFY_RESUME      1       /* callback before returning to user */
 #define TIF_SIGPENDING         2       /* signal pending */
 #define TIF_NEED_RESCHED       3       /* rescheduling necessary */
-#define TIF_RESTORE_SIGMASK    4       /* restore signal mask in do_signal() */
 #define TIF_USEDFPU            8       /* FPU was used by this task
                                         * this quantum (SMP) */
 #define TIF_POLLING_NRFLAG     9       /* true if poll_idle() is polling
diff --git a/arch/um/include/asm/thread_info.h 
b/arch/um/include/asm/thread_info.h
index 4eecd960ee8c..565b7db73083 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -60,7 +60,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTART_BLOCK      4
 #define TIF_MEMDIE             5       /* is terminating due to OOM killer */
 #define TIF_SYSCALL_AUDIT      6
-#define TIF_RESTORE_SIGMASK    7
 #define TIF_NOTIFY_RESUME      8
 #define TIF_SECCOMP            9       /* secure computing */
 
diff --git a/arch/unicore32/include/asm/thread_info.h 
b/arch/unicore32/include/asm/thread_info.h
index 5fb728f3b49a..0f38f6072839 100644
--- a/arch/unicore32/include/asm/thread_info.h
+++ b/arch/unicore32/include/asm/thread_info.h
@@ -119,7 +119,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NOTIFY_RESUME      2       /* callback before returning to user */
 #define TIF_SYSCALL_TRACE      8
 #define TIF_MEMDIE             18
-#define TIF_RESTORE_SIGMASK    20
 
 #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
diff --git a/arch/xtensa/include/asm/thread_info.h 
b/arch/xtensa/include/asm/thread_info.h
index f092cc3f4e66..27350241615c 100644
--- a/arch/xtensa/include/asm/thread_info.h
+++ b/arch/xtensa/include/asm/thread_info.h
@@ -108,7 +108,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SINGLESTEP         3       /* restore singlestep on return to user 
mode */
 #define TIF_SYSCALL_TRACEPOINT 4       /* syscall tracepoint instrumentation */
 #define TIF_MEMDIE             5       /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK    6       /* restore signal mask in do_signal() */
 #define TIF_NOTIFY_RESUME      7       /* callback before returning to user */
 #define TIF_DB_DISABLED                8       /* debug trap disabled for 
syscall */
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 520efbd355be..a5284f5ccb7c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -713,9 +713,6 @@ struct task_struct {
        /* Bit to tell LSMs we're in execve(): */
        unsigned                        in_execve:1;
        unsigned                        in_iowait:1;
-#ifndef TIF_RESTORE_SIGMASK
-       unsigned                        restore_sigmask:1;
-#endif
 #ifdef CONFIG_MEMCG
        unsigned                        in_user_fault:1;
 #endif
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 78678de45278..ac34566e762f 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -400,86 +400,9 @@ static inline void ptrace_signal_wake_up(struct 
task_struct *t, bool resume)
 
 void task_join_group_stop(struct task_struct *task);
 
-#ifdef TIF_RESTORE_SIGMASK
-/*
- * Legacy restore_sigmask accessors.  These are inefficient on
- * SMP architectures because they require atomic operations.
- */
-
-/**
- * set_restore_sigmask() - make sure real_sigmask processing gets done
- *
- * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
- * will run before returning to user mode, to process the flag.  For
- * all callers, TIF_SIGPENDING is already set or it's no harm to set
- * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
- * arch code will notice on return to user mode, in case those bits
- * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
- * signal code always gets run when TIF_RESTORE_SIGMASK is set.
- */
-static inline void set_restore_sigmask(void)
-{
-       set_thread_flag(TIF_RESTORE_SIGMASK);
-}
-
-static inline void clear_tsk_restore_sigmask(struct task_struct *task)
-{
-       clear_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
-}
-
-static inline void clear_restore_sigmask(void)
-{
-       clear_thread_flag(TIF_RESTORE_SIGMASK);
-}
-static inline bool test_tsk_restore_sigmask(struct task_struct *task)
-{
-       return test_tsk_thread_flag(task, TIF_RESTORE_SIGMASK);
-}
-static inline bool test_restore_sigmask(void)
-{
-       return test_thread_flag(TIF_RESTORE_SIGMASK);
-}
-static inline bool test_and_clear_restore_sigmask(void)
-{
-       return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
-}
-
-#else  /* TIF_RESTORE_SIGMASK */
-
-/* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
-static inline void set_restore_sigmask(void)
-{
-       current->restore_sigmask = true;
-}
-static inline void clear_tsk_restore_sigmask(struct task_struct *task)
-{
-       task->restore_sigmask = false;
-}
-static inline void clear_restore_sigmask(void)
-{
-       current->restore_sigmask = false;
-}
-static inline bool test_restore_sigmask(void)
-{
-       return current->restore_sigmask;
-}
-static inline bool test_tsk_restore_sigmask(struct task_struct *task)
-{
-       return task->restore_sigmask;
-}
-static inline bool test_and_clear_restore_sigmask(void)
-{
-       if (!current->restore_sigmask)
-               return false;
-       current->restore_sigmask = false;
-       return true;
-}
-#endif
-
 static inline void restore_saved_sigmask(void)
 {
-       if (test_and_clear_restore_sigmask())
-               __set_current_blocked(&current->real_blocked);
+       __set_current_blocked(&current->real_blocked);
 }
 
 extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 5ed6126e1cc5..08e25bbb04f4 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -963,8 +963,6 @@ int ptrace_request(struct task_struct *child, long request,
                child->real_blocked = new_set;
                spin_unlock_irq(&child->sighand->siglock);
 
-               clear_tsk_restore_sigmask(child);
-
                ret = 0;
                break;
        }
diff --git a/kernel/signal.c b/kernel/signal.c
index c37d4f209699..1358e6bf02d3 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2734,12 +2734,6 @@ static void signal_delivered(struct ksignal *ksig, int 
stepping)
 {
        sigset_t blocked;
 
-       /* A signal was successfully delivered, and the
-          saved sigmask was stored on the signal frame,
-          and will be restored by sigreturn.  So we can
-          simply clear the restore sigmask flag.  */
-       clear_restore_sigmask();
-
        sigorsets(&blocked, &current->blocked, &ksig->ka.sa.sa_mask);
        if (!(ksig->ka.sa.sa_flags & SA_NODEFER))
                sigaddset(&blocked, ksig->sig);
@@ -2940,7 +2934,6 @@ EXPORT_SYMBOL(sigprocmask);
 
 static int set_sigmask(sigset_t *newset)
 {
-       set_restore_sigmask();
        sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
        __set_current_blocked(newset);
 
-- 
2.21.0.dirty

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