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authorMark Rutland <mark.rutland@arm.com>2017-10-23 14:07:29 -0700
committerIngo Molnar <mingo@kernel.org>2017-10-25 11:01:08 +0200
commit6aa7de059173a986114ac43b8f50b297a86f09a8 (patch)
tree77666afe795e022914ca26433d61686c694dc4fd /fs/userfaultfd.c
parentb03a0fe0c5e4b46dcd400d27395b124499554a71 (diff)
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>
Diffstat (limited to 'fs/userfaultfd.c')
-rw-r--r--fs/userfaultfd.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 1c713fd5b3e6..f46d133c0949 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -381,7 +381,7 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
* 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 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
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 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
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 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
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;