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Subject[PATCH 5.10 141/157] kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()
Date
From: Oleg Nesterov <oleg@redhat.com>

commit 5abbe51a526253b9f003e9a0a195638dc882d660 upstream.

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 <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210201174641.GA17871@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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(-)

--- a/fs/select.c
+++ b/fs/select.c
@@ -1055,10 +1055,9 @@ static long do_restart_poll(struct resta

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 __us
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 __us
} else
restart_block->poll.has_timeout = 0;

- ret = -ERESTART_RESTARTBLOCK;
+ ret = set_restart_fn(restart_block, do_restart_poll);
}
return ret;
}
--- 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
/*
@@ -39,6 +40,18 @@ enum {

#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
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2730,14 +2730,13 @@ 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) {
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -848,9 +848,9 @@ static int alarm_timer_nsleep(const cloc
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;
}

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1957,9 +1957,9 @@ long hrtimer_nanosleep(ktime_t rqtp, con
}

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;
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1480,8 +1480,8 @@ static int posix_cpu_nsleep(const clocki
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;
}

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