linux-kernel - [PATCH 1/2] aio: simplify the usage of restore_saved_sigmask

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Date:   Fri, 7 Jun 2019 12:31:54 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Benjamin LaHaise <bcrl@...ck.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        David Laight <David.Laight@...LAB.COM>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Eric Wong <e@...24.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-aio@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] aio: simplify the usage of restore_saved_sigmask_unless()

Move the signal_pending() check and restore_saved_sigmask_unless()
into do_io_getevents() and simplify the callers.

The only complication is that non-restartable io_getevents() and
io_getevents_time32() have to translate ERESTARTNOHAND into EINTR.
They do not need restore_saved_sigmask_unless(), but it is harmless
and WARN_ON(!TIF_SIGPENDING) will be usefule after the next patch.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 fs/aio.c | 34 ++++++++--------------------------
 1 file changed, 8 insertions(+), 26 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 8200f97..944eef7 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -2034,6 +2034,7 @@ static long do_io_getevents(aio_context_t ctx_id,
 {
 	ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
 	struct kioctx *ioctx = lookup_ioctx(ctx_id);
+	bool interrupted;
 	long ret = -EINVAL;
 
 	if (likely(ioctx)) {
@@ -2042,6 +2043,11 @@ static long do_io_getevents(aio_context_t ctx_id,
 		percpu_ref_put(&ioctx->users);
 	}
 
+	interrupted = signal_pending(current);
+	restore_saved_sigmask_unless(interrupted);
+	if (interrupted && !ret)
+		ret = -ERESTARTNOHAND;
+
 	return ret;
 }
 
@@ -2072,7 +2078,7 @@ SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
 		return -EFAULT;
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
-	if (!ret && signal_pending(current))
+	if (ret == -ERESTARTNOHAND)
 		ret = -EINTR;
 	return ret;
 }
@@ -2094,7 +2100,6 @@ SYSCALL_DEFINE6(io_pgetevents,
 {
 	struct __aio_sigset	ksig = { NULL, };
 	struct timespec64	ts;
-	bool interrupted;
 	int ret;
 
 	if (timeout && unlikely(get_timespec64(&ts, timeout)))
@@ -2109,11 +2114,6 @@ SYSCALL_DEFINE6(io_pgetevents,
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
 
-	interrupted = signal_pending(current);
-	restore_saved_sigmask_unless(interrupted);
-	if (interrupted && !ret)
-		ret = -ERESTARTNOHAND;
-
 	return ret;
 }
 
@@ -2129,7 +2129,6 @@ SYSCALL_DEFINE6(io_pgetevents_time32,
 {
 	struct __aio_sigset	ksig = { NULL, };
 	struct timespec64	ts;
-	bool interrupted;
 	int ret;
 
 	if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
@@ -2145,11 +2144,6 @@ SYSCALL_DEFINE6(io_pgetevents_time32,
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
 
-	interrupted = signal_pending(current);
-	restore_saved_sigmask_unless(interrupted);
-	if (interrupted && !ret)
-		ret = -ERESTARTNOHAND;
-
 	return ret;
 }
 
@@ -2170,7 +2164,7 @@ SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
 		return -EFAULT;
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
-	if (!ret && signal_pending(current))
+	if (ret == -ERESTARTNOHAND)
 		ret = -EINTR;
 	return ret;
 }
@@ -2196,7 +2190,6 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents,
 {
 	struct __compat_aio_sigset ksig = { NULL, };
 	struct timespec64 t;
-	bool interrupted;
 	int ret;
 
 	if (timeout && get_old_timespec32(&t, timeout))
@@ -2211,11 +2204,6 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents,
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
 
-	interrupted = signal_pending(current);
-	restore_saved_sigmask_unless(interrupted);
-	if (interrupted && !ret)
-		ret = -ERESTARTNOHAND;
-
 	return ret;
 }
 
@@ -2231,7 +2219,6 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
 {
 	struct __compat_aio_sigset ksig = { NULL, };
 	struct timespec64 t;
-	bool interrupted;
 	int ret;
 
 	if (timeout && get_timespec64(&t, timeout))
@@ -2246,11 +2233,6 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
 
-	interrupted = signal_pending(current);
-	restore_saved_sigmask_unless(interrupted);
-	if (interrupted && !ret)
-		ret = -ERESTARTNOHAND;
-
 	return ret;
 }
 #endif
-- 
2.5.0