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, 3 insertions, 8 deletions

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d682049c07b2..e2a66e12fbc6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2400,7 +2400,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 			  const sigset_t __user *sig, size_t sigsz)
 {
 	struct io_cq_ring *ring = ctx->cq_ring;
-	sigset_t ksigmask, sigsaved;
 	int ret;
 
 	if (io_cqring_events(ring) >= min_events)
@@ -2410,21 +2409,17 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 #ifdef CONFIG_COMPAT
 		if (in_compat_syscall())
 			ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
-						      &ksigmask, &sigsaved, sigsz);
+						      sigsz);
 		else
 #endif
-			ret = set_user_sigmask(sig, &ksigmask,
-					       &sigsaved, sigsz);
+			ret = set_user_sigmask(sig, sigsz);
 
 		if (ret)
 			return ret;
 	}
 
 	ret = wait_event_interruptible(ctx->wait, io_cqring_events(ring) >= min_events);
-
-	if (sig)
-		restore_user_sigmask(sig, &sigsaved, ret == -ERESTARTSYS);
-
+	restore_saved_sigmask_unless(ret == -ERESTARTSYS);
 	if (ret == -ERESTARTSYS)
 		ret = -EINTR;