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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 /arch/x86/kernel/espfix_64.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 'arch/x86/kernel/espfix_64.c')
-rw-r--r--arch/x86/kernel/espfix_64.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index 9c4e7ba6870c..7d7715dde901 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -155,14 +155,14 @@ void init_espfix_ap(int cpu)
page = cpu/ESPFIX_STACKS_PER_PAGE;
/* Did another CPU already set this up? */
- stack_page = ACCESS_ONCE(espfix_pages[page]);
+ stack_page = READ_ONCE(espfix_pages[page]);
if (likely(stack_page))
goto done;
mutex_lock(&espfix_init_mutex);
/* Did we race on the lock? */
- stack_page = ACCESS_ONCE(espfix_pages[page]);
+ stack_page = READ_ONCE(espfix_pages[page]);
if (stack_page)
goto unlock_done;
@@ -200,7 +200,7 @@ void init_espfix_ap(int cpu)
set_pte(&pte_p[n*PTE_STRIDE], pte);
/* Job is done for this CPU and any CPU which shares this page */
- ACCESS_ONCE(espfix_pages[page]) = stack_page;
+ WRITE_ONCE(espfix_pages[page], stack_page);
unlock_done:
mutex_unlock(&espfix_init_mutex);