locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()
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>
diff --git a/fs/aio.c b/fs/aio.c
index 5a24872..e6de7715 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -576,7 +576,7 @@
* actually has a cancel function, hence the cmpxchg()
*/
- cancel = ACCESS_ONCE(kiocb->ki_cancel);
+ cancel = READ_ONCE(kiocb->ki_cancel);
do {
if (!cancel || cancel == KIOCB_CANCELLED)
return -EINVAL;
diff --git a/fs/buffer.c b/fs/buffer.c
index 170df85..32ce01f 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1692,7 +1692,8 @@
BUG_ON(!PageLocked(page));
if (!page_has_buffers(page))
- create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state);
+ create_empty_buffers(page, 1 << READ_ONCE(inode->i_blkbits),
+ b_state);
return page_buffers(page);
}
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index 8e704d1..0083bd4 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -373,7 +373,7 @@
struct fscrypt_info *prev;
if (ci == NULL)
- ci = ACCESS_ONCE(inode->i_crypt_info);
+ ci = READ_ONCE(inode->i_crypt_info);
if (ci == NULL)
return;
diff --git a/fs/direct-io.c b/fs/direct-io.c
index b53e66d..98fe132 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1152,7 +1152,7 @@
get_block_t get_block, dio_iodone_t end_io,
dio_submit_t submit_io, int flags)
{
- unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);
+ unsigned i_blkbits = READ_ONCE(inode->i_blkbits);
unsigned blkbits = i_blkbits;
unsigned blocksize_mask = (1 << blkbits) - 1;
ssize_t retval = -EINVAL;
diff --git a/fs/exec.c b/fs/exec.c
index 3e14ba2..1d6243d 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1911,7 +1911,7 @@
return;
do {
- old = ACCESS_ONCE(mm->flags);
+ old = READ_ONCE(mm->flags);
new = (old & ~MMF_DUMPABLE_MASK) | value;
} while (cmpxchg(&mm->flags, old, new) != old);
}
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 448a111..57bf296 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -724,7 +724,7 @@
* F_SETSIG can change ->signum lockless in parallel, make
* sure we read it once and use the same value throughout.
*/
- int signum = ACCESS_ONCE(fown->signum);
+ int signum = READ_ONCE(fown->signum);
if (!sigio_perm(p, fown, signum))
return;
diff --git a/fs/fs_pin.c b/fs/fs_pin.c
index e747b3d..2d07f29 100644
--- a/fs/fs_pin.c
+++ b/fs/fs_pin.c
@@ -78,7 +78,7 @@
while (1) {
struct hlist_node *p;
rcu_read_lock();
- p = ACCESS_ONCE(m->mnt_pins.first);
+ p = READ_ONCE(m->mnt_pins.first);
if (!p) {
rcu_read_unlock();
break;
@@ -92,7 +92,7 @@
while (1) {
struct hlist_node *q;
rcu_read_lock();
- q = ACCESS_ONCE(p->first);
+ q = READ_ONCE(p->first);
if (!q) {
rcu_read_unlock();
break;
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 13c65dd..a42d893 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -33,7 +33,7 @@
* Lockless access is OK, because file->private data is set
* once during mount and is valid until the file is released.
*/
- return ACCESS_ONCE(file->private_data);
+ return READ_ONCE(file->private_data);
}
static void fuse_request_init(struct fuse_req *req, struct page **pages,
diff --git a/fs/inode.c b/fs/inode.c
index d1e35b5..fd40102 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2090,7 +2090,7 @@
WARN_ON_ONCE(flags & ~mask);
do {
- old_flags = ACCESS_ONCE(inode->i_flags);
+ old_flags = READ_ONCE(inode->i_flags);
new_flags = (old_flags & ~mask) | flags;
} while (unlikely(cmpxchg(&inode->i_flags, old_flags,
new_flags) != old_flags));
diff --git a/fs/namei.c b/fs/namei.c
index c75ea03..40a0f34 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1209,7 +1209,7 @@
/* Given that we're not holding a lock here, we retain the value in a
* local variable for each dentry as we look at it so that we don't see
* the components of that value change under us */
- while (managed = ACCESS_ONCE(path->dentry->d_flags),
+ while (managed = READ_ONCE(path->dentry->d_flags),
managed &= DCACHE_MANAGED_DENTRY,
unlikely(managed != 0)) {
/* Allow the filesystem to manage the transit without i_mutex
@@ -1394,7 +1394,7 @@
unsigned managed;
int ret;
- while (managed = ACCESS_ONCE(path->dentry->d_flags),
+ while (managed = READ_ONCE(path->dentry->d_flags),
unlikely(managed & DCACHE_MANAGED_DENTRY)) {
/* Allow the filesystem to manage the transit without i_mutex
* being held.
diff --git a/fs/namespace.c b/fs/namespace.c
index d18deb4..e158ec6 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -353,7 +353,7 @@
* incremented count after it has set MNT_WRITE_HOLD.
*/
smp_mb();
- while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
+ while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
cpu_relax();
/*
* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 5ceaeb1..f439f1c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1081,7 +1081,7 @@
int error;
if (flags & LOOKUP_RCU) {
- parent = ACCESS_ONCE(dentry->d_parent);
+ parent = READ_ONCE(dentry->d_parent);
dir = d_inode_rcu(parent);
if (!dir)
return -ECHILD;
@@ -1168,7 +1168,7 @@
nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
out_valid:
if (flags & LOOKUP_RCU) {
- if (parent != ACCESS_ONCE(dentry->d_parent))
+ if (parent != READ_ONCE(dentry->d_parent))
return -ECHILD;
} else
dput(parent);
@@ -1582,7 +1582,7 @@
struct inode *dir;
if (flags & LOOKUP_RCU) {
- parent = ACCESS_ONCE(dentry->d_parent);
+ parent = READ_ONCE(dentry->d_parent);
dir = d_inode_rcu(parent);
if (!dir)
return -ECHILD;
@@ -1596,7 +1596,7 @@
ret = -ECHILD;
if (!(flags & LOOKUP_RCU))
dput(parent);
- else if (parent != ACCESS_ONCE(dentry->d_parent))
+ else if (parent != READ_ONCE(dentry->d_parent))
return -ECHILD;
goto out;
}
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 77a8eac..375e8bf 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -453,7 +453,7 @@
cutime = sig->cutime;
cstime = sig->cstime;
cgtime = sig->cgtime;
- rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
+ rsslim = READ_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
/* add up live thread stats at the group level */
if (whole) {
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 99dff22..03afd51 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -27,7 +27,7 @@
poll_wait(file, &p->ns->poll, wait);
- event = ACCESS_ONCE(ns->event);
+ event = READ_ONCE(ns->event);
if (m->poll_event != event) {
m->poll_event = event;
res |= POLLERR | POLLPRI;
diff --git a/fs/splice.c b/fs/splice.c
index f3084cc..39e2dc0 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -253,7 +253,7 @@
*/
int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
{
- unsigned int buffers = ACCESS_ONCE(pipe->buffers);
+ unsigned int buffers = READ_ONCE(pipe->buffers);
spd->nr_pages_max = buffers;
if (buffers <= PIPE_DEF_BUFFERS)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 1c713fd..f46d133 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -381,7 +381,7 @@
* in __get_user_pages if userfaultfd_release waits on the
* caller of handle_userfault to release the mmap_sem.
*/
- if (unlikely(ACCESS_ONCE(ctx->released))) {
+ if (unlikely(READ_ONCE(ctx->released))) {
/*
* Don't return VM_FAULT_SIGBUS in this case, so a non
* cooperative manager can close the uffd after the
@@ -477,7 +477,7 @@
vmf->flags, reason);
up_read(&mm->mmap_sem);
- if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&
+ if (likely(must_wait && !READ_ONCE(ctx->released) &&
(return_to_userland ? !signal_pending(current) :
!fatal_signal_pending(current)))) {
wake_up_poll(&ctx->fd_wqh, POLLIN);
@@ -586,7 +586,7 @@
set_current_state(TASK_KILLABLE);
if (ewq->msg.event == 0)
break;
- if (ACCESS_ONCE(ctx->released) ||
+ if (READ_ONCE(ctx->released) ||
fatal_signal_pending(current)) {
/*
* &ewq->wq may be queued in fork_event, but
@@ -833,7 +833,7 @@
struct userfaultfd_wake_range range = { .len = 0, };
unsigned long new_flags;
- ACCESS_ONCE(ctx->released) = true;
+ WRITE_ONCE(ctx->released, true);
if (!mmget_not_zero(mm))
goto wakeup;
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 51bf7b8..1299759 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -592,9 +592,9 @@
* a transiently forward state. Instead, we can see the LSN in a
* transiently behind state if we happen to race with a cycle wrap.
*/
- cur_cycle = ACCESS_ONCE(log->l_curr_cycle);
+ cur_cycle = READ_ONCE(log->l_curr_cycle);
smp_rmb();
- cur_block = ACCESS_ONCE(log->l_curr_block);
+ cur_block = READ_ONCE(log->l_curr_block);
if ((CYCLE_LSN(lsn) > cur_cycle) ||
(CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {