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6aa7de0591
Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.
However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:
----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()
// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
103 lines
2.0 KiB
C
103 lines
2.0 KiB
C
#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include "internal.h"
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#include "mount.h"
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static DEFINE_SPINLOCK(pin_lock);
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void pin_remove(struct fs_pin *pin)
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{
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spin_lock(&pin_lock);
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hlist_del_init(&pin->m_list);
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hlist_del_init(&pin->s_list);
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spin_unlock(&pin_lock);
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spin_lock_irq(&pin->wait.lock);
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pin->done = 1;
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wake_up_locked(&pin->wait);
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spin_unlock_irq(&pin->wait.lock);
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}
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void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
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{
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spin_lock(&pin_lock);
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if (p)
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hlist_add_head(&pin->s_list, p);
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hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
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spin_unlock(&pin_lock);
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}
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void pin_insert(struct fs_pin *pin, struct vfsmount *m)
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{
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pin_insert_group(pin, m, &m->mnt_sb->s_pins);
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}
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void pin_kill(struct fs_pin *p)
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{
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wait_queue_entry_t wait;
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if (!p) {
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rcu_read_unlock();
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return;
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}
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init_wait(&wait);
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spin_lock_irq(&p->wait.lock);
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if (likely(!p->done)) {
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p->done = -1;
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spin_unlock_irq(&p->wait.lock);
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rcu_read_unlock();
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p->kill(p);
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return;
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}
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if (p->done > 0) {
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spin_unlock_irq(&p->wait.lock);
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rcu_read_unlock();
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return;
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}
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__add_wait_queue(&p->wait, &wait);
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while (1) {
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set_current_state(TASK_UNINTERRUPTIBLE);
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spin_unlock_irq(&p->wait.lock);
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rcu_read_unlock();
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schedule();
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rcu_read_lock();
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if (likely(list_empty(&wait.entry)))
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break;
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/* OK, we know p couldn't have been freed yet */
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spin_lock_irq(&p->wait.lock);
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if (p->done > 0) {
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spin_unlock_irq(&p->wait.lock);
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break;
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}
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}
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rcu_read_unlock();
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}
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void mnt_pin_kill(struct mount *m)
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{
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while (1) {
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struct hlist_node *p;
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rcu_read_lock();
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p = READ_ONCE(m->mnt_pins.first);
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if (!p) {
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rcu_read_unlock();
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break;
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}
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pin_kill(hlist_entry(p, struct fs_pin, m_list));
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}
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}
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void group_pin_kill(struct hlist_head *p)
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{
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while (1) {
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struct hlist_node *q;
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rcu_read_lock();
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q = READ_ONCE(p->first);
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if (!q) {
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rcu_read_unlock();
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break;
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}
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pin_kill(hlist_entry(q, struct fs_pin, s_list));
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}
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}
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