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locking/atomics, EDAC/altera: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE() 

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 comments, leaving references
to ACCESS_ONCE() instances which have been removed. As a preparatory
step, this patch converts the Altera EDAC code and comments 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: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Thor Thayer <thor.thayer@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
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: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-2-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 14:07:12 -07:00 committed by Ingo Molnar
parent d3e632f07b
commit 332efa6374
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/edac/altera_edac.c
View File

@ -175,11 +175,11 @@ static ssize_t altr_sdr_mc_err_inject_write(struct file *file,
/* /*
* To trigger the error, we need to read the data back * To trigger the error, we need to read the data back
* (the data was written with errors above). * (the data was written with errors above).
* The ACCESS_ONCE macros and printk are used to prevent the * The READ_ONCE macros and printk are used to prevent the
* the compiler optimizing these reads out. * the compiler optimizing these reads out.
*/ */
reg = ACCESS_ONCE(ptemp[0]); reg = READ_ONCE(ptemp[0]);
read_reg = ACCESS_ONCE(ptemp[1]); read_reg = READ_ONCE(ptemp[1]);
/* Force Read */ /* Force Read */
rmb(); rmb();
@ -618,7 +618,7 @@ static ssize_t altr_edac_device_trig(struct file *file,
for (i = 0; i < (priv->trig_alloc_sz / sizeof(*ptemp)); i++) { for (i = 0; i < (priv->trig_alloc_sz / sizeof(*ptemp)); i++) {
/* Read data so we're in the correct state */ /* Read data so we're in the correct state */
rmb(); rmb();
if (ACCESS_ONCE(ptemp[i])) if (READ_ONCE(ptemp[i]))
result = -1; result = -1;
/* Toggle Error bit (it is latched), leave ECC enabled */ /* Toggle Error bit (it is latched), leave ECC enabled */
writel(error_mask, (drvdata->base + priv->set_err_ofst)); writel(error_mask, (drvdata->base + priv->set_err_ofst));
@ -635,7 +635,7 @@ static ssize_t altr_edac_device_trig(struct file *file,
/* Read out written data. ECC error caused here */ /* Read out written data. ECC error caused here */
for (i = 0; i < ALTR_TRIGGER_READ_WRD_CNT; i++) for (i = 0; i < ALTR_TRIGGER_READ_WRD_CNT; i++)
if (ACCESS_ONCE(ptemp[i]) != i) if (READ_ONCE(ptemp[i]) != i)
edac_printk(KERN_ERR, EDAC_DEVICE, edac_printk(KERN_ERR, EDAC_DEVICE,
"Read doesn't match written data\n"); "Read doesn't match written data\n");