Merge tag 'tif-task_work.arch-2020-12-14' of git://git.kernel.dk/linux-block

Pull TIF_NOTIFY_SIGNAL updates from Jens Axboe:
 "This sits on top of of the core entry/exit and x86 entry branch from
  the tip tree, which contains the generic and x86 parts of this work.

  Here we convert the rest of the archs to support TIF_NOTIFY_SIGNAL.

  With that done, we can get rid of JOBCTL_TASK_WORK from task_work and
  signal.c, and also remove a deadlock work-around in io_uring around
  knowing that signal based task_work waking is invoked with the sighand
  wait queue head lock.

  The motivation for this work is to decouple signal notify based
  task_work, of which io_uring is a heavy user of, from sighand. The
  sighand lock becomes a huge contention point, particularly for
  threaded workloads where it's shared between threads. Even outside of
  threaded applications it's slower than it needs to be.

  Roman Gershman <romger@amazon.com> reported that his networked
  workload dropped from 1.6M QPS at 80% CPU to 1.0M QPS at 100% CPU
  after io_uring was changed to use TIF_NOTIFY_SIGNAL. The time was all
  spent hammering on the sighand lock, showing 57% of the CPU time there
  [1].

  There are further cleanups possible on top of this. One example is
  TIF_PATCH_PENDING, where a patch already exists to use
  TIF_NOTIFY_SIGNAL instead. Hopefully this will also lead to more
  consolidation, but the work stands on its own as well"

[1] https://github.com/axboe/liburing/issues/215

* tag 'tif-task_work.arch-2020-12-14' of git://git.kernel.dk/linux-block: (28 commits)
  io_uring: remove 'twa_signal_ok' deadlock work-around
  kernel: remove checking for TIF_NOTIFY_SIGNAL
  signal: kill JOBCTL_TASK_WORK
  io_uring: JOBCTL_TASK_WORK is no longer used by task_work
  task_work: remove legacy TWA_SIGNAL path
  sparc: add support for TIF_NOTIFY_SIGNAL
  riscv: add support for TIF_NOTIFY_SIGNAL
  nds32: add support for TIF_NOTIFY_SIGNAL
  ia64: add support for TIF_NOTIFY_SIGNAL
  h8300: add support for TIF_NOTIFY_SIGNAL
  c6x: add support for TIF_NOTIFY_SIGNAL
  alpha: add support for TIF_NOTIFY_SIGNAL
  xtensa: add support for TIF_NOTIFY_SIGNAL
  arm: add support for TIF_NOTIFY_SIGNAL
  microblaze: add support for TIF_NOTIFY_SIGNAL
  hexagon: add support for TIF_NOTIFY_SIGNAL
  csky: add support for TIF_NOTIFY_SIGNAL
  openrisc: add support for TIF_NOTIFY_SIGNAL
  sh: add support for TIF_NOTIFY_SIGNAL
  um: add support for TIF_NOTIFY_SIGNAL
  ...

arch/alpha/include/asm/thread_info.h

@@ -62,6 +62,7 @@ register struct thread_info *__current_thread_info __asm__("$8");
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_SYSCALL_AUDIT	4	/* syscall audit active */
+#define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #define TIF_DIE_IF_KERNEL	9	/* dik recursion lock */
 #define TIF_MEMDIE		13	/* is terminating due to OOM killer */
 #define TIF_POLLING_NRFLAG	14	/* idle is polling for TIF_NEED_RESCHED */
@@ -71,6 +72,7 @@ register struct thread_info *__current_thread_info __asm__("$8");
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 
 /* Work to do on interrupt/exception return.  */

arch/alpha/kernel/entry.S

@@ -544,7 +544,7 @@ $ret_success:
 	.align	4
 	.type	work_pending, @function
 work_pending:
-	and	$17, _TIF_NOTIFY_RESUME | _TIF_SIGPENDING, $2
+	and	$17, _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL, $2
 	bne	$2, $work_notifysig
 
 $work_resched:

arch/alpha/kernel/signal.c

@@ -527,7 +527,7 @@ do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 			schedule();
 		} else {
 			local_irq_enable();
-			if (thread_flags & _TIF_SIGPENDING) {
+			if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) {
 				do_signal(regs, r0, r19);
 				r0 = 0;
 			} else {

arch/arc/include/asm/thread_info.h

@@ -79,6 +79,7 @@ static inline __attribute_const__ struct thread_info *current_thread_info(void)
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_SYSCALL_AUDIT	4	/* syscall auditing active */
+#define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #define TIF_SYSCALL_TRACE	15	/* syscall trace active */
 
 /* true if poll_idle() is polling TIF_NEED_RESCHED */
@@ -89,11 +90,12 @@ static inline __attribute_const__ struct thread_info *current_thread_info(void)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_MEMDIE		(1<<TIF_MEMDIE)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
-				 _TIF_NOTIFY_RESUME)
+				 _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL)
 
 /*
  * _TIF_ALLWORK_MASK includes SYSCALL_TRACE, but we don't need it.

arch/arc/kernel/entry.S

@@ -307,7 +307,8 @@ resume_user_mode_begin:
 	mov r0, sp	; pt_regs for arg to do_signal()/do_notify_resume()
 
 	GET_CURR_THR_INFO_FLAGS   r9
-	bbit0  r9, TIF_SIGPENDING, .Lchk_notify_resume
+	and.f  0,  r9, TIF_SIGPENDING|TIF_NOTIFY_SIGNAL
+	bz .Lchk_notify_resume
 
 	; Normal Trap/IRQ entry only saves Scratch (caller-saved) regs
 	; in pt_reg since the "C" ABI (kernel code) will automatically

arch/arc/kernel/signal.c

@@ -362,7 +362,7 @@ void do_signal(struct pt_regs *regs)
 
 	restart_scall = in_syscall(regs) && syscall_restartable(regs);
 
-	if (get_signal(&ksig)) {
+	if (test_thread_flag(TIF_SIGPENDING) && get_signal(&ksig)) {
 		if (restart_scall) {
 			arc_restart_syscall(&ksig.ka, regs);
 			syscall_wont_restart(regs);	/* No more restarts */

arch/arm/include/asm/thread_info.h

@@ -126,6 +126,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
  * thread information flags:
  *  TIF_USEDFPU		- FPU was used by this task this quantum (SMP)
  *  TIF_POLLING_NRFLAG	- true if poll_idle() is polling TIF_NEED_RESCHED
+ *
+ * Any bit in the range of 0..15 will cause do_work_pending() to be invoked.
  */
 #define TIF_SIGPENDING		0	/* signal pending */
 #define TIF_NEED_RESCHED	1	/* rescheduling necessary */
@@ -135,6 +137,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
 #define TIF_SYSCALL_AUDIT	5	/* syscall auditing active */
 #define TIF_SYSCALL_TRACEPOINT	6	/* syscall tracepoint instrumentation */
 #define TIF_SECCOMP		7	/* seccomp syscall filtering active */
+#define TIF_NOTIFY_SIGNAL	8	/* signal notifications exist */
 
 #define TIF_USING_IWMMXT	17
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
@@ -148,6 +151,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 
 /* Checks for any syscall work in entry-common.S */
@@ -158,7 +162,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
  * Change these and you break ASM code in entry-common.S
  */
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
-				 _TIF_NOTIFY_RESUME | _TIF_UPROBE)
+				 _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
+				 _TIF_NOTIFY_SIGNAL)
 
 #endif /* __KERNEL__ */
 #endif /* __ASM_ARM_THREAD_INFO_H */

arch/arm/kernel/entry-common.S

@@ -53,7 +53,7 @@ __ret_fast_syscall:
 	cmp	r2, #TASK_SIZE
 	blne	addr_limit_check_failed
 	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
-	tst	r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
+	movs	r1, r1, lsl #16
 	bne	fast_work_pending
 
 
@@ -90,7 +90,7 @@ __ret_fast_syscall:
 	cmp	r2, #TASK_SIZE
 	blne	addr_limit_check_failed
 	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
-	tst	r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
+	movs	r1, r1, lsl #16
 	beq	no_work_pending
  UNWIND(.fnend		)
 ENDPROC(ret_fast_syscall)
@@ -131,7 +131,7 @@ ENTRY(ret_to_user_from_irq)
 	cmp	r2, #TASK_SIZE
 	blne	addr_limit_check_failed
 	ldr	r1, [tsk, #TI_FLAGS]
-	tst	r1, #_TIF_WORK_MASK
+	movs	r1, r1, lsl #16
 	bne	slow_work_pending
 no_work_pending:
 	asm_trace_hardirqs_on save = 0

arch/arm/kernel/entry-v7m.S

@@ -59,7 +59,7 @@ __irq_entry:
 
 	get_thread_info tsk
 	ldr	r2, [tsk, #TI_FLAGS]
-	tst	r2, #_TIF_WORK_MASK
+	movs	r2, r2, lsl #16
 	beq	2f			@ no work pending
 	mov	r0, #V7M_SCB_ICSR_PENDSVSET
 	str	r0, [r1, V7M_SCB_ICSR]	@ raise PendSV

arch/arm/kernel/signal.c

@@ -655,7 +655,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 			if (unlikely(!user_mode(regs)))
 				return 0;
 			local_irq_enable();
-			if (thread_flags & _TIF_SIGPENDING) {
+			if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
 				int restart = do_signal(regs, syscall);
 				if (unlikely(restart)) {
 					/*

arch/arm64/include/asm/thread_info.h

@@ -64,6 +64,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define TIF_FOREIGN_FPSTATE	3	/* CPU's FP state is not current's */
 #define TIF_UPROBE		4	/* uprobe breakpoint or singlestep */
 #define TIF_MTE_ASYNC_FAULT	5	/* MTE Asynchronous Tag Check Fault */
+#define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
 #define TIF_SYSCALL_TRACE	8	/* syscall trace active */
 #define TIF_SYSCALL_AUDIT	9	/* syscall auditing */
 #define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
@@ -93,10 +94,12 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define _TIF_32BIT		(1 << TIF_32BIT)
 #define _TIF_SVE		(1 << TIF_SVE)
 #define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
-				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT)
+				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
+				 _TIF_NOTIFY_SIGNAL)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \

arch/arm64/kernel/signal.c

@@ -939,7 +939,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
 					       (void __user *)NULL, current);
 			}
 
-			if (thread_flags & _TIF_SIGPENDING)
+			if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 				do_signal(regs);
 
 			if (thread_flags & _TIF_NOTIFY_RESUME) {

arch/c6x/include/asm/thread_info.h

@@ -82,6 +82,7 @@ struct thread_info *current_thread_info(void)
 #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_NOTIFY_SIGNAL	5	/* signal notifications exist */
 
 #define TIF_MEMDIE		17	/* OOM killer killed process */
 

arch/c6x/kernel/asm-offsets.c

@@ -116,6 +116,7 @@ void foo(void)
 	DEFINE(_TIF_NOTIFY_RESUME, (1<<TIF_NOTIFY_RESUME));
 	DEFINE(_TIF_SIGPENDING, (1<<TIF_SIGPENDING));
 	DEFINE(_TIF_NEED_RESCHED, (1<<TIF_NEED_RESCHED));
+	DEFINE(_TIF_NOTIFY_SIGNAL, (1<<TIF_NOTIFY_SIGNAL));
 
 	DEFINE(_TIF_ALLWORK_MASK, TIF_ALLWORK_MASK);
 	DEFINE(_TIF_WORK_MASK, TIF_WORK_MASK);

arch/c6x/kernel/signal.c

@@ -13,6 +13,7 @@
 #include <linux/syscalls.h>
 #include <linux/tracehook.h>
 
+#include <asm/asm-offsets.h>
 #include <asm/ucontext.h>
 #include <asm/cacheflush.h>
 
@@ -313,7 +314,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 				 int syscall)
 {
 	/* deal with pending signal delivery */
-	if (thread_info_flags & (1 << TIF_SIGPENDING))
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs, syscall);
 
 	if (thread_info_flags & (1 << TIF_NOTIFY_RESUME))

arch/csky/include/asm/thread_info.h

@@ -64,6 +64,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_TRACE	4	/* syscall trace active */
 #define TIF_SYSCALL_TRACEPOINT	5       /* syscall tracepoint instrumentation */
 #define TIF_SYSCALL_AUDIT	6	/* syscall auditing */
+#define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
 #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() */
@@ -75,6 +76,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_MEMDIE		(1 << TIF_MEMDIE)
@@ -82,7 +84,8 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
-				 _TIF_NOTIFY_RESUME | _TIF_UPROBE)
+				 _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
+				 _TIF_NOTIFY_SIGNAL)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)

arch/csky/kernel/signal.c

@@ -257,7 +257,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
 		uprobe_notify_resume(regs);
 
 	/* Handle pending signal delivery */
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {

arch/h8300/include/asm/thread_info.h

@@ -73,6 +73,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
 #define TIF_SYSCALL_TRACEPOINT	8	/* for ftrace syscall instrumentation */
 #define TIF_POLLING_NRFLAG	9	/* true if poll_idle() is polling TIF_NEED_RESCHED */
+#define TIF_NOTIFY_SIGNAL	10	/* signal notifications exist */
 
 /* as above, but as bit values */
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
@@ -83,6 +84,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 
 /* work to do in syscall trace */
 #define _TIF_WORK_SYSCALL_MASK	(_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
@@ -92,7 +94,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_ALLWORK_MASK	(_TIF_SYSCALL_TRACE | _TIF_SIGPENDING      | \
 				 _TIF_NEED_RESCHED  | _TIF_SYSCALL_AUDIT   | \
 				 _TIF_SINGLESTEP    | _TIF_NOTIFY_RESUME   | \
-				 _TIF_SYSCALL_TRACEPOINT)
+				 _TIF_SYSCALL_TRACEPOINT | _TIF_NOTIFY_SIGNAL)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		(_TIF_ALLWORK_MASK & ~(_TIF_SYSCALL_TRACE | \

arch/h8300/kernel/signal.c

@@ -279,7 +279,7 @@ static void do_signal(struct pt_regs *regs)
 
 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags)
 {
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME)

arch/hexagon/include/asm/thread_info.h

@@ -95,6 +95,7 @@ register struct thread_info *__current_thread_info asm(QUOTED_THREADINFO_REG);
 #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() */
+#define TIF_NOTIFY_SIGNAL	7       /* signal notifications exist */
 /* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE              17      /* OOM killer killed process */
 
@@ -103,6 +104,7 @@ register struct thread_info *__current_thread_info asm(QUOTED_THREADINFO_REG);
 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 
 /* work to do on interrupt/exception return - All but TIF_SYSCALL_TRACE */
 #define _TIF_WORK_MASK          (0x0000FFFF & ~_TIF_SYSCALL_TRACE)

arch/hexagon/kernel/process.c

@@ -174,7 +174,7 @@ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
 		return 1;
 	}
 
-	if (thread_info_flags & _TIF_SIGPENDING) {
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
 		do_signal(regs);
 		return 1;
 	}

arch/ia64/include/asm/thread_info.h

@@ -103,6 +103,7 @@ struct thread_info {
 #define TIF_SYSCALL_TRACE	2	/* syscall trace active */
 #define TIF_SYSCALL_AUDIT	3	/* syscall auditing active */
 #define TIF_SINGLESTEP		4	/* restore singlestep on return to user mode */
+#define TIF_NOTIFY_SIGNAL	5	/* signal notification exist */
 #define TIF_NOTIFY_RESUME	6	/* resumption notification requested */
 #define TIF_MEMDIE		17	/* is terminating due to OOM killer */
 #define TIF_MCA_INIT		18	/* this task is processing MCA or INIT */
@@ -115,6 +116,7 @@ struct thread_info {
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SYSCALL_TRACEAUDIT	(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_MCA_INIT		(1 << TIF_MCA_INIT)
@@ -124,7 +126,7 @@ struct thread_info {
 
 /* "work to do on user-return" bits */
 #define TIF_ALLWORK_MASK	(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SYSCALL_AUDIT|\
-				 _TIF_NEED_RESCHED|_TIF_SYSCALL_TRACE)
+				 _TIF_NEED_RESCHED|_TIF_SYSCALL_TRACE|_TIF_NOTIFY_SIGNAL)
 /* like TIF_ALLWORK_BITS but sans TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT */
 #define TIF_WORK_MASK		(TIF_ALLWORK_MASK&~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT))
 

arch/ia64/kernel/process.c

@@ -171,7 +171,8 @@ do_notify_resume_user(sigset_t *unused, struct sigscratch *scr, long in_syscall)
 	}
 
 	/* deal with pending signal delivery */
-	if (test_thread_flag(TIF_SIGPENDING)) {
+	if (test_thread_flag(TIF_SIGPENDING) ||
+	    test_thread_flag(TIF_NOTIFY_SIGNAL)) {
 		local_irq_enable();	/* force interrupt enable */
 		ia64_do_signal(scr, in_syscall);
 	}

arch/m68k/include/asm/thread_info.h

@@ -60,6 +60,7 @@ static inline struct thread_info *current_thread_info(void)
  * bits 0-7 are tested at every exception exit
  * bits 8-15 are also tested at syscall exit
  */
+#define TIF_NOTIFY_SIGNAL	4
 #define TIF_NOTIFY_RESUME	5	/* callback before returning to user */
 #define TIF_SIGPENDING		6	/* signal pending */
 #define TIF_NEED_RESCHED	7	/* rescheduling necessary */

arch/m68k/kernel/signal.c

@@ -1133,7 +1133,8 @@ static void do_signal(struct pt_regs *regs)
 
 void do_notify_resume(struct pt_regs *regs)
 {
-	if (test_thread_flag(TIF_SIGPENDING))
+	if (test_thread_flag(TIF_NOTIFY_SIGNAL) ||
+	    test_thread_flag(TIF_SIGPENDING))
 		do_signal(regs);
 
 	if (test_thread_flag(TIF_NOTIFY_RESUME))

arch/mips/include/asm/thread_info.h

@@ -115,6 +115,7 @@ 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_NOTIFY_SIGNAL	7	/* signal notifications exist */
 #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 */
@@ -139,6 +140,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SECCOMP		(1<<TIF_SECCOMP)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_UPROBE		(1<<TIF_UPROBE)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_USEDFPU		(1<<TIF_USEDFPU)
 #define _TIF_NOHZ		(1<<TIF_NOHZ)
 #define _TIF_FIXADE		(1<<TIF_FIXADE)
@@ -164,7 +166,7 @@ static inline struct thread_info *current_thread_info(void)
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		\
 	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_NOTIFY_RESUME |	\
-	 _TIF_UPROBE)
+	 _TIF_UPROBE | _TIF_NOTIFY_SIGNAL)
 /* work to do on any return to u-space */
 #define _TIF_ALLWORK_MASK	(_TIF_NOHZ | _TIF_WORK_MASK |		\
 				 _TIF_WORK_SYSCALL_EXIT |		\

arch/mips/kernel/signal.c

@@ -903,7 +903,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 		uprobe_notify_resume(regs);
 
 	/* deal with pending signal delivery */
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {

arch/nds32/include/asm/thread_info.h

@@ -48,6 +48,7 @@ struct thread_info {
 #define TIF_NEED_RESCHED	2
 #define TIF_SINGLESTEP		3
 #define TIF_NOTIFY_RESUME	4	/* callback before returning to user */
+#define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #define TIF_SYSCALL_TRACE	8
 #define TIF_POLLING_NRFLAG	17
 #define TIF_MEMDIE		18
@@ -57,6 +58,7 @@ struct thread_info {
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)

arch/nds32/kernel/ex-exit.S

@@ -120,7 +120,7 @@ work_pending:
 	andi	$p1, $r1, #_TIF_NEED_RESCHED
 	bnez	$p1, work_resched
 
-	andi	$p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME
+	andi	$p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME|#_TIF_NOTIFY_SIGNAL
 	beqz	$p1, no_work_pending
 
 	move	$r0, $sp			! 'regs'

arch/nds32/kernel/signal.c

@@ -376,7 +376,7 @@ static void do_signal(struct pt_regs *regs)
 asmlinkage void
 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags)
 {
-	if (thread_flags & _TIF_SIGPENDING)
+	if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (thread_flags & _TIF_NOTIFY_RESUME)

arch/nios2/include/asm/thread_info.h

@@ -86,6 +86,7 @@ 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_NOTIFY_SIGNAL	7	/* signal notifications exist */
 #define TIF_RESTORE_SIGMASK	9	/* restore signal mask in do_signal() */
 
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling
@@ -97,6 +98,7 @@ 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_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 

arch/nios2/kernel/signal.c

@@ -306,7 +306,8 @@ asmlinkage int do_notify_resume(struct pt_regs *regs)
 	if (!user_mode(regs))
 		return 0;
 
-	if (test_thread_flag(TIF_SIGPENDING)) {
+	if (test_thread_flag(TIF_SIGPENDING) ||
+	    test_thread_flag(TIF_NOTIFY_SIGNAL)) {
 		int restart = do_signal(regs);
 
 		if (unlikely(restart)) {

arch/openrisc/include/asm/thread_info.h

@@ -98,6 +98,7 @@ register struct thread_info *current_thread_info_reg asm("r10");
 #define TIF_SINGLESTEP		4	/* restore singlestep on return to user
 					 * mode
 					 */
+#define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #define TIF_SYSCALL_TRACEPOINT  8       /* for ftrace syscall instrumentation */
 #define TIF_RESTORE_SIGMASK     9
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling						 * TIF_NEED_RESCHED
@@ -109,6 +110,7 @@ register struct thread_info *current_thread_info_reg asm("r10");
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP		(1<<TIF_SINGLESTEP)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 
 

arch/openrisc/kernel/signal.c

@@ -299,7 +299,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 			if (unlikely(!user_mode(regs)))
 				return 0;
 			local_irq_enable();
-			if (thread_flags & _TIF_SIGPENDING) {
+			if (thread_flags & (_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)) {
 				int restart = do_signal(regs, syscall);
 				if (unlikely(restart)) {
 					/*

arch/parisc/include/asm/thread_info.h

@@ -52,6 +52,7 @@ struct thread_info {
 #define TIF_POLLING_NRFLAG	3	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_32BIT               4       /* 32 bit binary */
 #define TIF_MEMDIE		5	/* is terminating due to OOM killer */
+#define TIF_NOTIFY_SIGNAL	6	/* signal notifications exist */
 #define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
 #define TIF_NOTIFY_RESUME	8	/* callback before returning to user */
 #define TIF_SINGLESTEP		9	/* single stepping? */
@@ -61,6 +62,7 @@ struct thread_info {
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_32BIT		(1 << TIF_32BIT)
@@ -72,7 +74,7 @@ struct thread_info {
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 
 #define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
-                                 _TIF_NEED_RESCHED)
+                                 _TIF_NEED_RESCHED | _TIF_NOTIFY_SIGNAL)
 #define _TIF_SYSCALL_TRACE_MASK (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP |	\
 				 _TIF_BLOCKSTEP | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)

arch/parisc/kernel/signal.c

@@ -603,7 +603,8 @@ do_signal(struct pt_regs *regs, long in_syscall)
 
 void do_notify_resume(struct pt_regs *regs, long in_syscall)
 {
-	if (test_thread_flag(TIF_SIGPENDING))
+	if (test_thread_flag(TIF_SIGPENDING) ||
+	    test_thread_flag(TIF_NOTIFY_SIGNAL))
 		do_signal(regs, in_syscall);
 
 	if (test_thread_flag(TIF_NOTIFY_RESUME))

arch/powerpc/include/asm/thread_info.h

@@ -90,6 +90,7 @@ void arch_setup_new_exec(void);
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_SIGPENDING		1	/* signal pending */
 #define TIF_NEED_RESCHED	2	/* rescheduling necessary */
+#define TIF_NOTIFY_SIGNAL	3	/* signal notifications exist */
 #define TIF_SYSCALL_EMU		4	/* syscall emulation active */
 #define TIF_RESTORE_TM		5	/* need to restore TM FP/VEC/VSX */
 #define TIF_PATCH_PENDING	6	/* pending live patching update */
@@ -115,6 +116,7 @@ void arch_setup_new_exec(void);
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 #define _TIF_32BIT		(1<<TIF_32BIT)
 #define _TIF_RESTORE_TM		(1<<TIF_RESTORE_TM)
@@ -136,7 +138,8 @@ void arch_setup_new_exec(void);
 
 #define _TIF_USER_WORK_MASK	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
 				 _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
-				 _TIF_RESTORE_TM | _TIF_PATCH_PENDING)
+				 _TIF_RESTORE_TM | _TIF_PATCH_PENDING | \
+				 _TIF_NOTIFY_SIGNAL)
 #define _TIF_PERSYSCALL_MASK	(_TIF_RESTOREALL|_TIF_NOERROR)
 
 /* Bits in local_flags */

arch/powerpc/kernel/signal.c

@@ -318,7 +318,7 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 	if (thread_info_flags & _TIF_PATCH_PENDING)
 		klp_update_patch_state(current);
 
-	if (thread_info_flags & _TIF_SIGPENDING) {
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
 		BUG_ON(regs != current->thread.regs);
 		do_signal(current);
 	}

arch/riscv/include/asm/thread_info.h

@@ -74,6 +74,7 @@ struct thread_info {
 #define TIF_SYSCALL_TRACEPOINT  6       /* syscall tracepoint instrumentation */
 #define TIF_SYSCALL_AUDIT	7	/* syscall auditing */
 #define TIF_SECCOMP		8	/* syscall secure computing */
+#define TIF_NOTIFY_SIGNAL	9	/* signal notifications exist */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
@@ -82,9 +83,11 @@ struct thread_info {
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 
 #define _TIF_WORK_MASK \
-	(_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED)
+	(_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+	 _TIF_NOTIFY_SIGNAL)
 
 #define _TIF_SYSCALL_WORK \
 	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT | \

arch/riscv/kernel/signal.c

@@ -310,7 +310,7 @@ asmlinkage __visible void do_notify_resume(struct pt_regs *regs,
 					   unsigned long thread_info_flags)
 {
 	/* Handle pending signal delivery */
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME)

arch/s390/include/asm/thread_info.h

@@ -65,6 +65,7 @@ void arch_setup_new_exec(void);
 #define TIF_GUARDED_STORAGE	4	/* load guarded storage control block */
 #define TIF_PATCH_PENDING	5	/* pending live patching update */
 #define TIF_PGSTE		6	/* New mm's will use 4K page tables */
+#define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
 #define TIF_ISOLATE_BP		8	/* Run process with isolated BP */
 #define TIF_ISOLATE_BP_GUEST	9	/* Run KVM guests with isolated BP */
 
@@ -82,6 +83,7 @@ void arch_setup_new_exec(void);
 #define TIF_SYSCALL_TRACEPOINT	27	/* syscall tracepoint instrumentation */
 
 #define _TIF_NOTIFY_RESUME	BIT(TIF_NOTIFY_RESUME)
+#define _TIF_NOTIFY_SIGNAL	BIT(TIF_NOTIFY_SIGNAL)
 #define _TIF_SIGPENDING		BIT(TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	BIT(TIF_NEED_RESCHED)
 #define _TIF_UPROBE		BIT(TIF_UPROBE)

arch/s390/kernel/entry.S

@@ -52,7 +52,8 @@ STACK_SIZE  = 1 << STACK_SHIFT
 STACK_INIT = STACK_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE
 
 _TIF_WORK	= (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
-		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING)
+		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING | \
+		   _TIF_NOTIFY_SIGNAL)
 _TIF_TRACE	= (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
 		   _TIF_SYSCALL_TRACEPOINT)
 _CIF_WORK	= (_CIF_FPU)
@@ -486,8 +487,8 @@ ENTRY(system_call)
 #endif
 	TSTMSK	__PT_FLAGS(%r11),_PIF_SYSCALL_RESTART
 	jo	.Lsysc_syscall_restart
-	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
-	jo	.Lsysc_sigpending
+	TSTMSK	__TI_flags(%r12),(_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)
+	jnz	.Lsysc_sigpending
 	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
 	jo	.Lsysc_notify_resume
 	j	.Lsysc_return
@@ -865,8 +866,8 @@ ENTRY(io_int_handler)
 	TSTMSK	__TI_flags(%r12),_TIF_PATCH_PENDING
 	jo	.Lio_patch_pending
 #endif
-	TSTMSK	__TI_flags(%r12),_TIF_SIGPENDING
-	jo	.Lio_sigpending
+	TSTMSK	__TI_flags(%r12),(_TIF_SIGPENDING|_TIF_NOTIFY_SIGNAL)
+	jnz	.Lio_sigpending
 	TSTMSK	__TI_flags(%r12),_TIF_NOTIFY_RESUME
 	jo	.Lio_notify_resume
 	TSTMSK	__TI_flags(%r12),_TIF_GUARDED_STORAGE

arch/s390/kernel/signal.c

@@ -472,7 +472,7 @@ void do_signal(struct pt_regs *regs)
 	current->thread.system_call =
 		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
 
-	if (get_signal(&ksig)) {
+	if (test_thread_flag(TIF_SIGPENDING) && get_signal(&ksig)) {
 		/* Whee!  Actually deliver the signal.  */
 		if (current->thread.system_call) {
 			regs->int_code = current->thread.system_call;

arch/sh/include/asm/thread_info.h

@@ -105,6 +105,7 @@ extern void init_thread_xstate(void);
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_SIGPENDING		1	/* signal pending */
 #define TIF_NEED_RESCHED	2	/* rescheduling necessary */
+#define TIF_NOTIFY_SIGNAL	3	/* signal notifications exist */
 #define TIF_SINGLESTEP		4	/* singlestepping active */
 #define TIF_SYSCALL_AUDIT	5	/* syscall auditing active */
 #define TIF_SECCOMP		6	/* secure computing */
@@ -116,6 +117,7 @@ extern void init_thread_xstate(void);
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
@@ -132,7 +134,7 @@ extern void init_thread_xstate(void);
 #define _TIF_ALLWORK_MASK	(_TIF_SYSCALL_TRACE | _TIF_SIGPENDING      | \
 				 _TIF_NEED_RESCHED  | _TIF_SYSCALL_AUDIT   | \
 				 _TIF_SINGLESTEP    | _TIF_NOTIFY_RESUME   | \
-				 _TIF_SYSCALL_TRACEPOINT)
+				 _TIF_SYSCALL_TRACEPOINT | _TIF_NOTIFY_SIGNAL)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		(_TIF_ALLWORK_MASK & ~(_TIF_SYSCALL_TRACE | \

arch/sh/kernel/signal_32.c

@@ -499,7 +499,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
 				 unsigned long thread_info_flags)
 {
 	/* deal with pending signal delivery */
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs, save_r0);
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME)

arch/sparc/include/asm/thread_info_32.h

@@ -104,6 +104,7 @@ register struct thread_info *current_thread_info_reg asm("g6");
 #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_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #define TIF_USEDFPU		8	/* FPU was used by this task
 					 * this quantum (SMP) */
 #define TIF_POLLING_NRFLAG	9	/* true if poll_idle() is polling
@@ -115,11 +116,12 @@ register struct thread_info *current_thread_info_reg asm("g6");
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_USEDFPU		(1<<TIF_USEDFPU)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 
 #define _TIF_DO_NOTIFY_RESUME_MASK	(_TIF_NOTIFY_RESUME | \
-					 _TIF_SIGPENDING)
+					 _TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)
 
 #define is_32bit_task()	(1)
 

arch/sparc/include/asm/thread_info_64.h

@@ -180,7 +180,7 @@ extern struct thread_info *current_thread_info(void);
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
-/* flag bit 4 is available */
+#define TIF_NOTIFY_SIGNAL	4	/* signal notifications exist */
 #define TIF_UNALIGNED		5	/* allowed to do unaligned accesses */
 #define TIF_UPROBE		6	/* breakpointed or singlestepped */
 #define TIF_32BIT		7	/* 32-bit binary */
@@ -200,6 +200,7 @@ extern struct thread_info *current_thread_info(void);
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
 #define _TIF_UNALIGNED		(1<<TIF_UNALIGNED)
 #define _TIF_UPROBE		(1<<TIF_UPROBE)
 #define _TIF_32BIT		(1<<TIF_32BIT)
@@ -213,7 +214,8 @@ extern struct thread_info *current_thread_info(void);
 				 _TIF_DO_NOTIFY_RESUME_MASK | \
 				 _TIF_NEED_RESCHED)
 #define _TIF_DO_NOTIFY_RESUME_MASK	(_TIF_NOTIFY_RESUME | \
-					 _TIF_SIGPENDING | _TIF_UPROBE)
+					 _TIF_SIGPENDING | _TIF_UPROBE | \
+					 _TIF_NOTIFY_SIGNAL)
 
 #define is_32bit_task()	(test_thread_flag(TIF_32BIT))
 

arch/sparc/kernel/signal_32.c

@@ -521,7 +521,7 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
 		      unsigned long thread_info_flags)
 {
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs, orig_i0);
 	if (thread_info_flags & _TIF_NOTIFY_RESUME)
 		tracehook_notify_resume(regs);

arch/sparc/kernel/signal_64.c

@@ -549,7 +549,7 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long
 	user_exit();
 	if (thread_info_flags & _TIF_UPROBE)
 		uprobe_notify_resume(regs);
-	if (thread_info_flags & _TIF_SIGPENDING)
+	if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 		do_signal(regs, orig_i0);
 	if (thread_info_flags & _TIF_NOTIFY_RESUME)
 		tracehook_notify_resume(regs);

arch/um/include/asm/thread_info.h

@@ -57,6 +57,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_SIGPENDING		1	/* signal pending */
 #define TIF_NEED_RESCHED	2	/* rescheduling necessary */
+#define TIF_NOTIFY_SIGNAL	3	/* signal notifications exist */
 #define TIF_RESTART_BLOCK	4
 #define TIF_MEMDIE		5	/* is terminating due to OOM killer */
 #define TIF_SYSCALL_AUDIT	6
@@ -67,6 +68,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_MEMDIE		(1 << TIF_MEMDIE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)

arch/um/kernel/process.c

@@ -99,7 +99,8 @@ void interrupt_end(void)
 
 	if (need_resched())
 		schedule();
-	if (test_thread_flag(TIF_SIGPENDING))
+	if (test_thread_flag(TIF_SIGPENDING) ||
+	    test_thread_flag(TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 	if (test_thread_flag(TIF_NOTIFY_RESUME))
 		tracehook_notify_resume(regs);

arch/xtensa/include/asm/thread_info.h

@@ -111,18 +111,21 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NEED_RESCHED	2	/* rescheduling necessary */
 #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_NOTIFY_SIGNAL	5	/* signal notifications exist */
 #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 */
 #define TIF_SYSCALL_AUDIT	9	/* syscall auditing active */
 #define TIF_SECCOMP		10	/* secure computing */
+#define TIF_MEMDIE		11	/* is terminating due to OOM killer */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP		(1<<TIF_SINGLESTEP)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
+#define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
+#define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1<<TIF_SECCOMP)
 

arch/xtensa/kernel/entry.S

@@ -500,8 +500,8 @@ common_exception_return:
 	 */
 
 	_bbsi.l	a4, TIF_NEED_RESCHED, 3f
-	_bbsi.l	a4, TIF_NOTIFY_RESUME, 2f
-	_bbci.l	a4, TIF_SIGPENDING, 5f
+	movi	a2, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL
+	bnone	a4, a2, 5f
 
 2:	l32i	a4, a1, PT_DEPC
 	bgeui	a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f

arch/xtensa/kernel/signal.c

@@ -498,7 +498,8 @@ static void do_signal(struct pt_regs *regs)
 
 void do_notify_resume(struct pt_regs *regs)
 {
-	if (test_thread_flag(TIF_SIGPENDING))
+	if (test_thread_flag(TIF_SIGPENDING) ||
+	    test_thread_flag(TIF_NOTIFY_SIGNAL))
 		do_signal(regs);
 
 	if (test_thread_flag(TIF_NOTIFY_RESUME))

fs/io_uring.c

@@ -1996,7 +1996,7 @@ static struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 	return __io_req_find_next(req);
 }
 
-static int io_req_task_work_add(struct io_kiocb *req, bool twa_signal_ok)
+static int io_req_task_work_add(struct io_kiocb *req)
 {
 	struct task_struct *tsk = req->task;
 	struct io_ring_ctx *ctx = req->ctx;
@@ -2013,7 +2013,7 @@ static int io_req_task_work_add(struct io_kiocb *req, bool twa_signal_ok)
 	 * will do the job.
 	 */
 	notify = TWA_NONE;
-	if (!(ctx->flags & IORING_SETUP_SQPOLL) && twa_signal_ok)
+	if (!(ctx->flags & IORING_SETUP_SQPOLL))
 		notify = TWA_SIGNAL;
 
 	ret = task_work_add(tsk, &req->task_work, notify);
@@ -2075,7 +2075,7 @@ static void io_req_task_queue(struct io_kiocb *req)
 	init_task_work(&req->task_work, io_req_task_submit);
 	percpu_ref_get(&req->ctx->refs);
 
-	ret = io_req_task_work_add(req, true);
+	ret = io_req_task_work_add(req);
 	if (unlikely(ret)) {
 		struct task_struct *tsk;
 
@@ -2197,7 +2197,7 @@ static void io_free_req_deferred(struct io_kiocb *req)
 	int ret;
 
 	init_task_work(&req->task_work, io_put_req_deferred_cb);
-	ret = io_req_task_work_add(req, true);
+	ret = io_req_task_work_add(req);
 	if (unlikely(ret)) {
 		struct task_struct *tsk;
 
@@ -3305,7 +3305,7 @@ static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
 
 	/* submit ref gets dropped, acquire a new one */
 	refcount_inc(&req->refs);
-	ret = io_req_task_work_add(req, true);
+	ret = io_req_task_work_add(req);
 	if (unlikely(ret)) {
 		struct task_struct *tsk;
 
@@ -4859,7 +4859,6 @@ struct io_poll_table {
 static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
 			   __poll_t mask, task_work_func_t func)
 {
-	bool twa_signal_ok;
 	int ret;
 
 	/* for instances that support it check for an event match first: */
@@ -4874,21 +4873,13 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll,
 	init_task_work(&req->task_work, func);
 	percpu_ref_get(&req->ctx->refs);
 
-	/*
-	 * If we using the signalfd wait_queue_head for this wakeup, then
-	 * it's not safe to use TWA_SIGNAL as we could be recursing on the
-	 * tsk->sighand->siglock on doing the wakeup. Should not be needed
-	 * either, as the normal wakeup will suffice.
-	 */
-	twa_signal_ok = (poll->head != &req->task->sighand->signalfd_wqh);
-
 	/*
 	 * If this fails, then the task is exiting. When a task exits, the
 	 * work gets canceled, so just cancel this request as well instead
 	 * of executing it. We can't safely execute it anyway, as we may not
 	 * have the needed state needed for it anyway.
 	 */
-	ret = io_req_task_work_add(req, twa_signal_ok);
+	ret = io_req_task_work_add(req);
 	if (unlikely(ret)) {
 		struct task_struct *tsk;
 
@@ -6862,13 +6853,8 @@ static int io_run_task_work_sig(void)
 		return 1;
 	if (!signal_pending(current))
 		return 0;
-	if (current->jobctl & JOBCTL_TASK_WORK) {
-		spin_lock_irq(&current->sighand->siglock);
-		current->jobctl &= ~JOBCTL_TASK_WORK;
-		recalc_sigpending();
-		spin_unlock_irq(&current->sighand->siglock);
-		return 1;
-	}
+	if (test_tsk_thread_flag(current, TIF_NOTIFY_SIGNAL))
+		return -ERESTARTSYS;
 	return -EINTR;
 }
 

include/linux/entry-common.h

@@ -21,10 +21,6 @@
 # define _TIF_UPROBE			(0)
 #endif
 
-#ifndef _TIF_NOTIFY_SIGNAL
-# define _TIF_NOTIFY_SIGNAL		(0)
-#endif
-
 /*
  * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
  */

include/linux/sched/jobctl.h

@@ -19,7 +19,6 @@ struct task_struct;
 #define JOBCTL_TRAPPING_BIT	21	/* switching to TRACED */
 #define JOBCTL_LISTENING_BIT	22	/* ptracer is listening for events */
 #define JOBCTL_TRAP_FREEZE_BIT	23	/* trap for cgroup freezer */
-#define JOBCTL_TASK_WORK_BIT	24	/* set by TWA_SIGNAL */
 
 #define JOBCTL_STOP_DEQUEUED	(1UL << JOBCTL_STOP_DEQUEUED_BIT)
 #define JOBCTL_STOP_PENDING	(1UL << JOBCTL_STOP_PENDING_BIT)
@@ -29,10 +28,9 @@ struct task_struct;
 #define JOBCTL_TRAPPING		(1UL << JOBCTL_TRAPPING_BIT)
 #define JOBCTL_LISTENING	(1UL << JOBCTL_LISTENING_BIT)
 #define JOBCTL_TRAP_FREEZE	(1UL << JOBCTL_TRAP_FREEZE_BIT)
-#define JOBCTL_TASK_WORK	(1UL << JOBCTL_TASK_WORK_BIT)
 
 #define JOBCTL_TRAP_MASK	(JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY)
-#define JOBCTL_PENDING_MASK	(JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK | JOBCTL_TASK_WORK)
+#define JOBCTL_PENDING_MASK	(JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK)
 
 extern bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask);
 extern void task_clear_jobctl_trapping(struct task_struct *task);

include/linux/sched/signal.h

@@ -361,7 +361,6 @@ static inline int task_sigpending(struct task_struct *p)
 
 static inline int signal_pending(struct task_struct *p)
 {
-#if defined(TIF_NOTIFY_SIGNAL)
 	/*
 	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
 	 * behavior in terms of ensuring that we break out of wait loops
@@ -369,7 +368,6 @@ static inline int signal_pending(struct task_struct *p)
 	 */
 	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
 		return 1;
-#endif
 	return task_sigpending(p);
 }
 

include/linux/tracehook.h

@@ -206,12 +206,10 @@ static inline void tracehook_notify_resume(struct pt_regs *regs)
  */
 static inline void tracehook_notify_signal(void)
 {
-#if defined(TIF_NOTIFY_SIGNAL)
 	clear_thread_flag(TIF_NOTIFY_SIGNAL);
 	smp_mb__after_atomic();
 	if (current->task_works)
 		task_work_run();
-#endif
 }
 
 /*
@@ -219,11 +217,9 @@ static inline void tracehook_notify_signal(void)
  */
 static inline void set_notify_signal(struct task_struct *task)
 {
-#if defined(TIF_NOTIFY_SIGNAL)
 	if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) &&
 	    !wake_up_state(task, TASK_INTERRUPTIBLE))
 		kick_process(task);
-#endif
 }
 
 #endif	/* <linux/tracehook.h> */

kernel/signal.c

@@ -2555,14 +2555,12 @@ bool get_signal(struct ksignal *ksig)
 	 * that the arch handlers don't all have to do it. If we get here
 	 * without TIF_SIGPENDING, just exit after running signal work.
 	 */
-#ifdef TIF_NOTIFY_SIGNAL
 	if (!IS_ENABLED(CONFIG_GENERIC_ENTRY)) {
 		if (test_thread_flag(TIF_NOTIFY_SIGNAL))
 			tracehook_notify_signal();
 		if (!task_sigpending(current))
 			return false;
 	}
-#endif
 
 	if (unlikely(uprobe_deny_signal()))
 		return false;
@@ -2576,26 +2574,6 @@ bool get_signal(struct ksignal *ksig)
 
 relock:
 	spin_lock_irq(&sighand->siglock);
-	/*
-	 * Make sure we can safely read ->jobctl() in task_work add. As Oleg
-	 * states:
-	 *
-	 * It pairs with mb (implied by cmpxchg) before READ_ONCE. So we
-	 * roughly have
-	 *
-	 *	task_work_add:				get_signal:
-	 *	STORE(task->task_works, new_work);	STORE(task->jobctl);
-	 *	mb();					mb();
-	 *	LOAD(task->jobctl);			LOAD(task->task_works);
-	 *
-	 * and we can rely on STORE-MB-LOAD [ in task_work_add].
-	 */
-	smp_store_mb(current->jobctl, current->jobctl & ~JOBCTL_TASK_WORK);
-	if (unlikely(current->task_works)) {
-		spin_unlock_irq(&sighand->siglock);
-		task_work_run();
-		goto relock;
-	}
 
 	/*
 	 * Every stopped thread goes here after wakeup. Check to see if

kernel/task_work.c

@@ -5,34 +5,6 @@
 
 static struct callback_head work_exited; /* all we need is ->next == NULL */
 
-/*
- * TWA_SIGNAL signaling - use TIF_NOTIFY_SIGNAL, if available, as it's faster
- * than TIF_SIGPENDING as there's no dependency on ->sighand. The latter is
- * shared for threads, and can cause contention on sighand->lock. Even for
- * the non-threaded case TIF_NOTIFY_SIGNAL is more efficient, as no locking
- * or IRQ disabling is involved for notification (or running) purposes.
- */
-static void task_work_notify_signal(struct task_struct *task)
-{
-#if defined(TIF_NOTIFY_SIGNAL)
-	set_notify_signal(task);
-#else
-	unsigned long flags;
-
-	/*
-	 * Only grab the sighand lock if we don't already have some
-	 * task_work pending. This pairs with the smp_store_mb()
-	 * in get_signal(), see comment there.
-	 */
-	if (!(READ_ONCE(task->jobctl) & JOBCTL_TASK_WORK) &&
-	    lock_task_sighand(task, &flags)) {
-		task->jobctl |= JOBCTL_TASK_WORK;
-		signal_wake_up(task, 0);
-		unlock_task_sighand(task, &flags);
-	}
-#endif
-}
-
 /**
  * task_work_add - ask the @task to execute @work->func()
  * @task: the task which should run the callback
@@ -76,7 +48,7 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
 		set_notify_resume(task);
 		break;
 	case TWA_SIGNAL:
-		task_work_notify_signal(task);
+		set_notify_signal(task);
 		break;
 	default:
 		WARN_ON_ONCE(1);