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Date:   Wed, 4 Dec 2019 16:09:52 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Ingo Molnar <mingo@kernel.org>,
        Jan Kratochvil <jan.kratochvil@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Pedro Alves <palves@redhat.com>, Peter Anvin <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [PATCH v3 1/4] introduce set_restart_fn() and arch_set_restart_data()
Message-ID: <20191204150952.GB14871@redhat.com>
References: <20191126110659.GA14042@redhat.com>
 <20191203141239.GA30688@redhat.com>
 <20191203141305.GB30688@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Preparation. Add the new helper which sets restart_block->fn and calls
the dummy arch_set_restart_data() helper.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 fs/select.c                    | 10 ++++------
 include/linux/thread_info.h    | 13 +++++++++++++
 kernel/futex.c                 |  3 +--
 kernel/time/alarmtimer.c       |  2 +-
 kernel/time/hrtimer.c          |  2 +-
 kernel/time/posix-cpu-timers.c |  2 +-
 6 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 53a0c14..e517960 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -1037,10 +1037,9 @@ static long do_restart_poll(struct restart_block *re=
start_block)
=20
 =09ret =3D do_sys_poll(ufds, nfds, to);
=20
-=09if (ret =3D=3D -ERESTARTNOHAND) {
-=09=09restart_block->fn =3D do_restart_poll;
-=09=09ret =3D -ERESTART_RESTARTBLOCK;
-=09}
+=09if (ret =3D=3D -ERESTARTNOHAND)
+=09=09ret =3D set_restart_fn(restart_block, do_restart_poll);
+
 =09return ret;
 }
=20
@@ -1062,7 +1061,6 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, u=
nsigned int, nfds,
 =09=09struct restart_block *restart_block;
=20
 =09=09restart_block =3D &current->restart_block;
-=09=09restart_block->fn =3D do_restart_poll;
 =09=09restart_block->poll.ufds =3D ufds;
 =09=09restart_block->poll.nfds =3D nfds;
=20
@@ -1073,7 +1071,7 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, u=
nsigned int, nfds,
 =09=09} else
 =09=09=09restart_block->poll.has_timeout =3D 0;
=20
-=09=09ret =3D -ERESTART_RESTARTBLOCK;
+=09=09ret =3D set_restart_fn(restart_block, do_restart_poll);
 =09}
 =09return ret;
 }
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 659a440..be124f0 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -11,6 +11,7 @@
 #include <linux/types.h>
 #include <linux/bug.h>
 #include <linux/restart_block.h>
+#include <linux/errno.h>
=20
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 /*
@@ -39,6 +40,18 @@ enum {
=20
 #ifdef __KERNEL__
=20
+#ifndef arch_set_restart_data
+#define arch_set_restart_data(restart) do { } while (0)
+#endif
+
+static inline long set_restart_fn(struct restart_block *restart,
+=09=09=09=09=09long (*fn)(struct restart_block *))
+{
+=09restart->fn =3D fn;
+=09arch_set_restart_data(restart);
+=09return -ERESTART_RESTARTBLOCK;
+}
+
 #ifndef THREAD_ALIGN
 #define THREAD_ALIGN=09THREAD_SIZE
 #endif
diff --git a/kernel/futex.c b/kernel/futex.c
index bd18f60..f4f20e9 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2753,14 +2753,13 @@ static int futex_wait(u32 __user *uaddr, unsigned i=
nt flags, u32 val,
 =09=09goto out;
=20
 =09restart =3D &current->restart_block;
-=09restart->fn =3D futex_wait_restart;
 =09restart->futex.uaddr =3D uaddr;
 =09restart->futex.val =3D val;
 =09restart->futex.time =3D *abs_time;
 =09restart->futex.bitset =3D bitset;
 =09restart->futex.flags =3D flags | FLAGS_HAS_TIMEOUT;
=20
-=09ret =3D -ERESTART_RESTARTBLOCK;
+=09ret =3D set_restart_fn(restart, futex_wait_restart);
=20
 out:
 =09if (to) {
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 451f9d0..a2ddf56 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -829,9 +829,9 @@ static int alarm_timer_nsleep(const clockid_t which_clo=
ck, int flags,
 =09if (flags =3D=3D TIMER_ABSTIME)
 =09=09return -ERESTARTNOHAND;
=20
-=09restart->fn =3D alarm_timer_nsleep_restart;
 =09restart->nanosleep.clockid =3D type;
 =09restart->nanosleep.expires =3D exp;
+=09set_restart_fn(restart, alarm_timer_nsleep_restart);
 =09return ret;
 }
=20
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 6560553..55f71c4 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1932,9 +1932,9 @@ long hrtimer_nanosleep(const struct timespec64 *rqtp,
 =09}
=20
 =09restart =3D &current->restart_block;
-=09restart->fn =3D hrtimer_nanosleep_restart;
 =09restart->nanosleep.clockid =3D t.timer.base->clockid;
 =09restart->nanosleep.expires =3D hrtimer_get_expires_tv64(&t.timer);
+=09set_restart_fn(restart, hrtimer_nanosleep_restart);
 out:
 =09destroy_hrtimer_on_stack(&t.timer);
 =09return ret;
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.=
c
index 42d512f..eacb0ca 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1335,8 +1335,8 @@ static int posix_cpu_nsleep(const clockid_t which_clo=
ck, int flags,
 =09=09if (flags & TIMER_ABSTIME)
 =09=09=09return -ERESTARTNOHAND;
=20
-=09=09restart_block->fn =3D posix_cpu_nsleep_restart;
 =09=09restart_block->nanosleep.clockid =3D which_clock;
+=09=09set_restart_fn(restart_block, posix_cpu_nsleep_restart);
 =09}
 =09return error;
 }
--=20
2.5.0