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

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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>
This commit is contained in:
Mark Rutland
2017-10-23 14:07:29 -07:00
committed by Ingo Molnar
parent b03a0fe0c5
commit 6aa7de0591
180 changed files with 383 additions and 385 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
sound/soc/xtensa/xtfpga-i2s.c
View File

@@ -165,7 +165,7 @@ static bool xtfpga_pcm_push_tx(struct xtfpga_i2s *i2s)
tx_substream = rcu_dereference(i2s->tx_substream);
tx_active = tx_substream && snd_pcm_running(tx_substream);
if (tx_active) {
unsigned tx_ptr = ACCESS_ONCE(i2s->tx_ptr);
unsigned tx_ptr = READ_ONCE(i2s->tx_ptr);
unsigned new_tx_ptr = i2s->tx_fn(i2s, tx_substream->runtime,
tx_ptr);
@@ -437,7 +437,7 @@ static int xtfpga_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
case SNDRV_PCM_TRIGGER_START:
case SNDRV_PCM_TRIGGER_RESUME:
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
ACCESS_ONCE(i2s->tx_ptr) = 0;
WRITE_ONCE(i2s->tx_ptr, 0);
rcu_assign_pointer(i2s->tx_substream, substream);
xtfpga_pcm_refill_fifo(i2s);
break;
@@ -459,7 +459,7 @@ static snd_pcm_uframes_t xtfpga_pcm_pointer(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct xtfpga_i2s *i2s = runtime->private_data;
snd_pcm_uframes_t pos = ACCESS_ONCE(i2s->tx_ptr);
snd_pcm_uframes_t pos = READ_ONCE(i2s->tx_ptr);
return pos < runtime->buffer_size ? pos : 0;
}