summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-10-23 14:07:24 -0700
committerIngo Molnar <mingo@kernel.org>2017-10-25 11:01:05 +0200
commit3587679d93d0b0e4c31e5a2ad1dffdfcb77e8526 (patch)
tree93a7f54d20aba02c26a9090679a68c6531d497a3
parent5cd38016d0c88e3f67528c1a7380a6d5c90859e9 (diff)
downloadlinux-3587679d93d0b0e4c31e5a2ad1dffdfcb77e8526.tar.bz2
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>
-rw-r--r--Documentation/filesystems/path-lookup.md6
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
------------------