[tip: x86/urgent] kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()

[tip-bot2 for Oleg Nesterov]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     5abbe51a526253b9f003e9a0a195638dc882d660
Gitweb:        
https://git.kernel.org/tip/5abbe51a526253b9f003e9a0a195638dc882d660
Author:        Oleg Nesterov <o...@redhat.com>
AuthorDate:    Mon, 01 Feb 2021 18:46:41 +01:00
Committer:     Thomas Gleixner <t...@linutronix.de>
CommitterDate: Tue, 16 Mar 2021 22:13:10 +01:00

kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()

Preparation for fixing get_nr_restart_syscall() on X86 for COMPAT.

Add a new helper which sets restart_block->fn and calls a dummy
arch_set_restart_data() helper.

Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code")
Signed-off-by: Oleg Nesterov <o...@redhat.com>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: sta...@vger.kernel.org
Link: https://lore.kernel.org/r/20210201174641.ga17...@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 37aaa83..945896d 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -1055,10 +1055,9 @@ static long do_restart_poll(struct restart_block 
*restart_block)
 
        ret = do_sys_poll(ufds, nfds, to);
 
-       if (ret == -ERESTARTNOHAND) {
-               restart_block->fn = do_restart_poll;
-               ret = -ERESTART_RESTARTBLOCK;
-       }
+       if (ret == -ERESTARTNOHAND)
+               ret = set_restart_fn(restart_block, do_restart_poll);
+
        return ret;
 }
 
@@ -1080,7 +1079,6 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, 
unsigned int, nfds,
                struct restart_block *restart_block;
 
                restart_block = &current->restart_block;
-               restart_block->fn = do_restart_poll;
                restart_block->poll.ufds = ufds;
                restart_block->poll.nfds = nfds;
 
@@ -1091,7 +1089,7 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, 
unsigned int, nfds,
                } else
                        restart_block->poll.has_timeout = 0;
 
-               ret = -ERESTART_RESTARTBLOCK;
+               ret = set_restart_fn(restart_block, do_restart_poll);
        }
        return ret;
 }
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 9b2158c..157762d 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>
 
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 /*
@@ -59,6 +60,18 @@ enum syscall_work_bit {
 
 #ifdef __KERNEL__
 
+#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,
+                                       long (*fn)(struct restart_block *))
+{
+       restart->fn = fn;
+       arch_set_restart_data(restart);
+       return -ERESTART_RESTARTBLOCK;
+}
+
 #ifndef THREAD_ALIGN
 #define THREAD_ALIGN   THREAD_SIZE
 #endif
diff --git a/kernel/futex.c b/kernel/futex.c
index e68db77..00febd6 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2728,14 +2728,13 @@ retry:
                goto out;
 
        restart = &current->restart_block;
-       restart->fn = futex_wait_restart;
        restart->futex.uaddr = uaddr;
        restart->futex.val = val;
        restart->futex.time = *abs_time;
        restart->futex.bitset = bitset;
        restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
 
-       ret = -ERESTART_RESTARTBLOCK;
+       ret = set_restart_fn(restart, futex_wait_restart);
 
 out:
        if (to) {
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 98d7a15..4d94e2b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -854,9 +854,9 @@ static int alarm_timer_nsleep(const clockid_t which_clock, 
int flags,
        if (flags == TIMER_ABSTIME)
                return -ERESTARTNOHAND;
 
-       restart->fn = alarm_timer_nsleep_restart;
        restart->nanosleep.clockid = type;
        restart->nanosleep.expires = exp;
+       set_restart_fn(restart, alarm_timer_nsleep_restart);
        return ret;
 }
 
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 788b9d1..5c9d968 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1957,9 +1957,9 @@ long hrtimer_nanosleep(ktime_t rqtp, const enum 
hrtimer_mode mode,
        }
 
        restart = &current->restart_block;
-       restart->fn = hrtimer_nanosleep_restart;
        restart->nanosleep.clockid = t.timer.base->clockid;
        restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
+       set_restart_fn(restart, hrtimer_nanosleep_restart);
 out:
        destroy_hrtimer_on_stack(&t.timer);
        return ret;
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index a71758e..9abe152 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1480,8 +1480,8 @@ static int posix_cpu_nsleep(const clockid_t which_clock, 
int flags,
                if (flags & TIMER_ABSTIME)
                        return -ERESTARTNOHAND;
 
-               restart_block->fn = posix_cpu_nsleep_restart;
                restart_block->nanosleep.clockid = which_clock;
+               set_restart_fn(restart_block, posix_cpu_nsleep_restart);
        }
        return error;
 }