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locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Browse source 
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 <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Mark Rutland 2017-10-23 14:07:29 -07:00 • committed by Ingo Molnar
commit 6aa7de0591
180 changed files with 383 additions and 385 deletions
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10
drivers/firewire/ohci.c
View file

@ -734,7 +734,7 @@ static unsigned int ar_search_last_active_buffer(struct ar_context *ctx,
__le16 res_count, next_res_count;
i = ar_first_buffer_index(ctx);
res_count = ACCESS_ONCE(ctx->descriptors[i].res_count);
res_count = READ_ONCE(ctx->descriptors[i].res_count);
/* A buffer that is not yet completely filled must be the last one. */
while (i != last && res_count == 0) {
@ -742,8 +742,7 @@ static unsigned int ar_search_last_active_buffer(struct ar_context *ctx,
/* Peek at the next descriptor. */
next_i = ar_next_buffer_index(i);
rmb(); /* read descriptors in order */
next_res_count = ACCESS_ONCE(
ctx->descriptors[next_i].res_count);
next_res_count = READ_ONCE(ctx->descriptors[next_i].res_count);
/*
* If the next descriptor is still empty, we must stop at this
* descriptor.
@ -759,8 +758,7 @@ static unsigned int ar_search_last_active_buffer(struct ar_context *ctx,
if (MAX_AR_PACKET_SIZE > PAGE_SIZE && i != last) {
next_i = ar_next_buffer_index(next_i);
rmb();
next_res_count = ACCESS_ONCE(
ctx->descriptors[next_i].res_count);
next_res_count = READ_ONCE(ctx->descriptors[next_i].res_count);
if (next_res_count != cpu_to_le16(PAGE_SIZE))
goto next_buffer_is_active;
}
@ -2812,7 +2810,7 @@ static int handle_ir_buffer_fill(struct context *context,
u32 buffer_dma;
req_count = le16_to_cpu(last->req_count);
res_count = le16_to_cpu(ACCESS_ONCE(last->res_count));
res_count = le16_to_cpu(READ_ONCE(last->res_count));
completed = req_count - res_count;
buffer_dma = le32_to_cpu(last->data_address);