[PATCH 1/2] select: change do_poll() to return -ERESTARTNOHAND rather than -EINTR

[Oleg Nesterov]

do_poll() returns -EINTR if interrupted and after that all its callers
have to translate it into -ERESTARTNOHAND. Change do_poll() to return
-ERESTARTNOHAND and update (simplify) the callers.

Note that this also unifies all users of restore_saved_sigmask_unless(),
see the next patch.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
 fs/select.c | 30 +++++++-----------------------
 1 file changed, 7 insertions(+), 23 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 1fc1b24..57712c3 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -925,7 +925,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
 		if (!count) {
 			count = wait->error;
 			if (signal_pending(current))
-				count = -EINTR;
+				count = -ERESTARTNOHAND;
 		}
 		if (count || timed_out)
 			break;
@@ -1040,7 +1040,7 @@ static long do_restart_poll(struct restart_block *restart_block)
 
 	ret = do_sys_poll(ufds, nfds, to);
 
-	if (ret == -EINTR) {
+	if (ret == -ERESTARTNOHAND) {
 		restart_block->fn = do_restart_poll;
 		ret = -ERESTART_RESTARTBLOCK;
 	}
@@ -1061,7 +1061,7 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
 
 	ret = do_sys_poll(ufds, nfds, to);
 
-	if (ret == -EINTR) {
+	if (ret == -ERESTARTNOHAND) {
 		struct restart_block *restart_block;
 
 		restart_block = &current->restart_block;
@@ -1102,11 +1102,7 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-
-	restore_saved_sigmask_unless(ret == -EINTR);
-	/* We can restart this syscall, usually */
-	if (ret == -EINTR)
-		ret = -ERESTARTNOHAND;
+	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
 	ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret);
 
 	return ret;
@@ -1135,11 +1131,7 @@ 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 == -EINTR);
-	/* We can restart this syscall, usually */
-	if (ret == -EINTR)
-		ret = -ERESTARTNOHAND;
+	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
 	ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret);
 
 	return ret;
@@ -1413,11 +1405,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, struct pollfd __user *, ufds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-
-	restore_saved_sigmask_unless(ret == -EINTR);
-	/* We can restart this syscall, usually */
-	if (ret == -EINTR)
-		ret = -ERESTARTNOHAND;
+	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
 	ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret);
 
 	return ret;
@@ -1446,11 +1434,7 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, struct pollfd __user *, ufds,
 		return ret;
 
 	ret = do_sys_poll(ufds, nfds, to);
-
-	restore_saved_sigmask_unless(ret == -EINTR);
-	/* We can restart this syscall, usually */
-	if (ret == -EINTR)
-		ret = -ERESTARTNOHAND;
+	restore_saved_sigmask_unless(ret == -ERESTARTNOHAND);
 	ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret);
 
 	return ret;
-- 
2.5.0