Revision 34b3d5344719d14fd2185b2d9459b3abcb8cf9d8 authored by Petr Mladek on 25 June 2021, 01:39:45 UTC, committed by Linus Torvalds on 25 June 2021, 02:40:54 UTC
Patch series "kthread_worker: Fix race between kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync()". This patchset fixes the race between kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync() including proper return value handling. This patch (of 2): Simple code refactoring as a preparation step for fixing a race between kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync(). It does not modify the existing behavior. Link: https://lkml.kernel.org/r/20210610133051.15337-2-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: <jenhaochen@google.com> Cc: Martin Liu <liumartin@google.com> Cc: Minchan Kim <minchan@google.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fs_pin.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include "internal.h"
#include "mount.h"
static DEFINE_SPINLOCK(pin_lock);
void pin_remove(struct fs_pin *pin)
{
spin_lock(&pin_lock);
hlist_del_init(&pin->m_list);
hlist_del_init(&pin->s_list);
spin_unlock(&pin_lock);
spin_lock_irq(&pin->wait.lock);
pin->done = 1;
wake_up_locked(&pin->wait);
spin_unlock_irq(&pin->wait.lock);
}
void pin_insert(struct fs_pin *pin, struct vfsmount *m)
{
spin_lock(&pin_lock);
hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
spin_unlock(&pin_lock);
}
void pin_kill(struct fs_pin *p)
{
wait_queue_entry_t wait;
if (!p) {
rcu_read_unlock();
return;
}
init_wait(&wait);
spin_lock_irq(&p->wait.lock);
if (likely(!p->done)) {
p->done = -1;
spin_unlock_irq(&p->wait.lock);
rcu_read_unlock();
p->kill(p);
return;
}
if (p->done > 0) {
spin_unlock_irq(&p->wait.lock);
rcu_read_unlock();
return;
}
__add_wait_queue(&p->wait, &wait);
while (1) {
set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irq(&p->wait.lock);
rcu_read_unlock();
schedule();
rcu_read_lock();
if (likely(list_empty(&wait.entry)))
break;
/* OK, we know p couldn't have been freed yet */
spin_lock_irq(&p->wait.lock);
if (p->done > 0) {
spin_unlock_irq(&p->wait.lock);
break;
}
}
rcu_read_unlock();
}
void mnt_pin_kill(struct mount *m)
{
while (1) {
struct hlist_node *p;
rcu_read_lock();
p = READ_ONCE(m->mnt_pins.first);
if (!p) {
rcu_read_unlock();
break;
}
pin_kill(hlist_entry(p, struct fs_pin, m_list));
}
}
void group_pin_kill(struct hlist_head *p)
{
while (1) {
struct hlist_node *q;
rcu_read_lock();
q = READ_ONCE(p->first);
if (!q) {
rcu_read_unlock();
break;
}
pin_kill(hlist_entry(q, struct fs_pin, s_list));
}
}
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