select: change do_poll() to return -ERESTARTNOHAND rather than -EINTR

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.

Linus:

: The *right* return value will actually be then chosen by
: poll_select_copy_remaining(), which will turn ERESTARTNOHAND to EINTR
: when it can't update the timeout.
:
: Except for the cases that use restart_block and do that instead and
: don't have the whole timeout restart issue as a result.

Link: http://lkml.kernel.org/r/20190606140852.GB13440@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Laight <David.Laight@aculab.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Eric Wong <e@80x24.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/select.c b/fs/select.c
index 1fc1b24..57712c3 100644 (file)
--- 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;