diff options
author | Mark Rutland <mark.rutland@arm.com> | 2017-10-23 14:07:29 -0700 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2017-10-25 11:01:08 +0200 |
commit | 6aa7de059173a986114ac43b8f50b297a86f09a8 (patch) | |
tree | 77666afe795e022914ca26433d61686c694dc4fd /fs/userfaultfd.c | |
parent | b03a0fe0c5e4b46dcd400d27395b124499554a71 (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.c | 8 |
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; |