signal: simplify set_user_sigmask/restore_user_sigmask

task->saved_sigmask and ->restore_sigmask are only used in the ret-from-
syscall paths.  This means that set_user_sigmask() can save ->blocked in
->saved_sigmask and do set_restore_sigmask() to indicate that ->blocked
was modified.

This way the callers do not need 2 sigset_t's passed to set/restore and
restore_user_sigmask() renamed to restore_saved_sigmask_unless() turns
into the trivial helper which just calls restore_saved_sigmask().

Link: http://lkml.kernel.org/r/20190606113206.GA9464@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Eric Wong <e@80x24.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: David Laight <David.Laight@aculab.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 8 deletions

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 4c74c768ae43..0f9c073d78d5 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2313,19 +2313,17 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
 		size_t, sigsetsize)
 {
 	int error;
-	sigset_t ksigmask, sigsaved;
 
 	/*
 	 * If the caller wants a certain signal mask to be set during the wait,
 	 * we apply it here.
 	 */
-	error = set_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize);
+	error = set_user_sigmask(sigmask, sigsetsize);
 	if (error)
 		return error;
 
 	error = do_epoll_wait(epfd, events, maxevents, timeout);
-
-	restore_user_sigmask(sigmask, &sigsaved, error == -EINTR);
+	restore_saved_sigmask_unless(error == -EINTR);
 
 	return error;
 }
@@ -2338,19 +2336,17 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 			compat_size_t, sigsetsize)
 {
 	long err;
-	sigset_t ksigmask, sigsaved;
 
 	/*
 	 * If the caller wants a certain signal mask to be set during the wait,
 	 * we apply it here.
 	 */
-	err = set_compat_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize);
+	err = set_compat_user_sigmask(sigmask, sigsetsize);
 	if (err)
 		return err;
 
 	err = do_epoll_wait(epfd, events, maxevents, timeout);
-
-	restore_user_sigmask(sigmask, &sigsaved, err == -EINTR);
+	restore_saved_sigmask_unless(err == -EINTR);
 
 	return err;
 }