linux-kernel - [PATCH 2/2] select: shift restore_saved_sigmask_unless() into poll_select_copy

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Date:   Thu, 6 Jun 2019 16:09:15 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Deepa Dinamani <deepa.kernel@...il.com>
Cc:     linux-kernel@...r.kernel.org, arnd@...db.de, dbueso@...e.de,
        axboe@...nel.dk, dave@...olabs.net, e@...24.org, jbaron@...mai.com,
        linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
        omar.kilani@...il.com, tglx@...utronix.de, stable@...r.kernel.org,
        Al Viro <viro@...IV.linux.org.uk>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Laight <David.Laight@...LAB.COM>
Subject: [PATCH 2/2] select: shift restore_saved_sigmask_unless() into
 poll_select_copy_remaining()

Now that restore_saved_sigmask_unless() is always called with the same
argument right before poll_select_copy_remaining() we can move it into
poll_select_copy_remaining() and make it the only caller of restore()
in fs/select.c.

The patch also renames poll_select_copy_remaining(), poll_select_finish()
looks better after this change.

kern_select() doesn't use set_user_sigmask(), so in this case
poll_select_finish() does restore_saved_sigmask_unless() "for no reason".
But this won't hurt, and WARN_ON(!TIF_SIGPENDING) is still valid.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 fs/select.c | 46 +++++++++++++---------------------------------
 1 file changed, 13 insertions(+), 33 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 57712c3..51ceec2 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -294,12 +294,14 @@ enum poll_time_type {
 	PT_OLD_TIMESPEC = 3,
 };
 
-static int poll_select_copy_remaining(struct timespec64 *end_time,
-				      void __user *p,
-				      enum poll_time_type pt_type, int ret)
+static int poll_select_finish(struct timespec64 *end_time,
+			      void __user *p,
+			      enum poll_time_type pt_type, int ret)
 {
 	struct timespec64 rts;
 
+	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
+
 	if (!p)
 		return ret;
 
@@ -714,9 +716,7 @@ static int kern_select(int n, fd_set __user *inp, fd_set __user *outp,
 	}
 
 	ret = core_sys_select(n, inp, outp, exp, to);
-	ret = poll_select_copy_remaining(&end_time, tvp, PT_TIMEVAL, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tvp, PT_TIMEVAL, ret);
 }
 
 SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
@@ -757,10 +757,7 @@ static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
 		return ret;
 
 	ret = core_sys_select(n, inp, outp, exp, to);
-	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
-	ret = poll_select_copy_remaining(&end_time, tsp, type, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tsp, type, ret);
 }
 
 /*
@@ -1102,10 +1099,7 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
-	ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tsp, PT_TIMESPEC, ret);
 }
 
 #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
@@ -1131,10 +1125,7 @@ SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds, unsigned int, nfds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
-	ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tsp, PT_OLD_TIMESPEC, ret);
 }
 #endif
 
@@ -1271,9 +1262,7 @@ static int do_compat_select(int n, compat_ulong_t __user *inp,
 	}
 
 	ret = compat_core_sys_select(n, inp, outp, exp, to);
-	ret = poll_select_copy_remaining(&end_time, tvp, PT_OLD_TIMEVAL, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tvp, PT_OLD_TIMEVAL, ret);
 }
 
 COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp,
@@ -1333,10 +1322,7 @@ static long do_compat_pselect(int n, compat_ulong_t __user *inp,
 		return ret;
 
 	ret = compat_core_sys_select(n, inp, outp, exp, to);
-	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
-	ret = poll_select_copy_remaining(&end_time, tsp, type, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tsp, type, ret);
 }
 
 COMPAT_SYSCALL_DEFINE6(pselect6_time64, int, n, compat_ulong_t __user *, inp,
@@ -1405,10 +1391,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
-	ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tsp, PT_OLD_TIMESPEC, ret);
 }
 #endif
 
@@ -1434,10 +1417,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, struct pollfd __user *, ufds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
-	ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret);
-
-	return ret;
+	return poll_select_finish(&end_time, tsp, PT_TIMESPEC, ret);
 }
 
 #endif
-- 
2.5.0