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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-10-23 14:07:24 -0700 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2017-10-25 11:01:05 +0200 |
commit | 3587679d93d0b0e4c31e5a2ad1dffdfcb77e8526 (patch) | |
tree | 93a7f54d20aba02c26a9090679a68c6531d497a3 /Documentation/filesystems | |
parent | 5cd38016d0c88e3f67528c1a7380a6d5c90859e9 (diff) | |
download | linux-stable-3587679d93d0b0e4c31e5a2ad1dffdfcb77e8526.tar.gz linux-stable-3587679d93d0b0e4c31e5a2ad1dffdfcb77e8526.tar.bz2 linux-stable-3587679d93d0b0e4c31e5a2ad1dffdfcb77e8526.zip |
locking/atomics, doc/filesystems: Convert ACCESS_ONCE() references
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 currently harmful.
However, for some features it is necessary to instrument reads and
writes separately, which is not possible with ACCESS_ONCE(). This
distinction is critical to correct operation.
It's possible to transform the bulk of kernel code using the Coccinelle
script below. However, this doesn't handle documentation, leaving
references to ACCESS_ONCE() instances which have been removed. As a
preparatory step, this patch converts the filesystems documentation to
use {READ,WRITE}_ONCE() consistently.
----
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: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.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
Link: http://lkml.kernel.org/r/1508792849-3115-14-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r-- | Documentation/filesystems/path-lookup.md | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/Documentation/filesystems/path-lookup.md b/Documentation/filesystems/path-lookup.md index 1b39e084a2b2..1933ef734e63 100644 --- a/Documentation/filesystems/path-lookup.md +++ b/Documentation/filesystems/path-lookup.md @@ -826,9 +826,9 @@ If the filesystem may need to revalidate dcache entries, then *is* passed the dentry but does not have access to the `inode` or the `seq` number from the `nameidata`, so it needs to be extra careful when accessing fields in the dentry. This "extra care" typically -involves using `ACCESS_ONCE()` or the newer [`READ_ONCE()`] to access -fields, and verifying the result is not NULL before using it. This -pattern can be see in `nfs_lookup_revalidate()`. +involves using [`READ_ONCE()`] to access fields, and verifying the +result is not NULL before using it. This pattern can be seen in +`nfs_lookup_revalidate()`. A pair of patterns ------------------ |