signals: add set_restore_sigmask

This adds the set_restore_sigmask() inline in <linux/thread_info.h> and
replaces every set_thread_flag(TIF_RESTORE_SIGMASK) with a call to it.  No
change, but abstracts the details of the flag protocol from all the calls.

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>

fs/compat.c

@@ -1720,7 +1720,7 @@ asmlinkage long compat_sys_pselect7(int n, compat_ulong_t __user *inp,
 		if (sigmask) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 					sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		}
 	} else if (sigmask)
 		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
@@ -1791,7 +1791,7 @@ asmlinkage long compat_sys_ppoll(struct pollfd __user *ufds,
 		if (sigmask) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 				sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		}
 		ret = -ERESTARTNOHAND;
 	} else if (sigmask)
@@ -2117,7 +2117,7 @@ asmlinkage long compat_sys_epoll_pwait(int epfd,
 		if (err == -EINTR) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 			       sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		} else
 			sigprocmask(SIG_SETMASK, &sigsaved, NULL);
 	}

fs/eventpoll.c

@@ -1279,7 +1279,7 @@ asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
 		if (error == -EINTR) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 			       sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		} else
 			sigprocmask(SIG_SETMASK, &sigsaved, NULL);
 	}
@@ -1309,4 +1309,3 @@ static int __init eventpoll_init(void)
 	return 0;
 }
 fs_initcall(eventpoll_init);
-

fs/select.c

@@ -498,7 +498,7 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
 		if (sigmask) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 					sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		}
 	} else if (sigmask)
 		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
@@ -805,7 +805,7 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
 		if (sigmask) {
 			memcpy(&current->saved_sigmask, &sigsaved,
 					sizeof(sigsaved));
-			set_thread_flag(TIF_RESTORE_SIGMASK);
+			set_restore_sigmask();
 		}
 		ret = -ERESTARTNOHAND;
 	} else if (sigmask)

include/linux/thread_info.h

@@ -92,6 +92,19 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
 #define set_need_resched()	set_thread_flag(TIF_NEED_RESCHED)
 #define clear_need_resched()	clear_thread_flag(TIF_NEED_RESCHED)
 
-#endif
+#ifdef TIF_RESTORE_SIGMASK
+/**
+ * set_restore_sigmask() - make sure saved_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.
+ */
+static inline void set_restore_sigmask(void)
+{
+	set_thread_flag(TIF_RESTORE_SIGMASK);
+}
+#endif	/* TIF_RESTORE_SIGMASK */
+
+#endif	/* __KERNEL__ */
 
 #endif /* _LINUX_THREAD_INFO_H */

kernel/compat.c

@@ -898,7 +898,7 @@ asmlinkage long compat_sys_rt_sigsuspend(compat_sigset_t __user *unewset, compat
 
 	current->state = TASK_INTERRUPTIBLE;
 	schedule();
-	set_thread_flag(TIF_RESTORE_SIGMASK);
+	set_restore_sigmask();
 	return -ERESTARTNOHAND;
 }
 #endif /* __ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND */
@@ -1080,4 +1080,3 @@ compat_sys_sysinfo(struct compat_sysinfo __user *info)
 
 	return 0;
 }
-

kernel/signal.c

@@ -2541,7 +2541,7 @@ asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
 
 	current->state = TASK_INTERRUPTIBLE;
 	schedule();
-	set_thread_flag(TIF_RESTORE_SIGMASK);
+	set_restore_sigmask();
 	return -ERESTARTNOHAND;
 }
 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */