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

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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 <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Acked-by: Thor Thayer <[email protected]>
Cc: Borislav Petkov <[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]
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 14:07:12 -07:00 • committed by Ingo Molnar
commit 332efa6374
1 changed files with 5 additions and 5 deletions
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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
* (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.
*/
reg = ACCESS_ONCE(ptemp[0]);
read_reg = ACCESS_ONCE(ptemp[1]);
reg = READ_ONCE(ptemp[0]);
read_reg = READ_ONCE(ptemp[1]);
/* Force Read */
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++) {
/* Read data so we're in the correct state */
rmb();
if (ACCESS_ONCE(ptemp[i]))
if (READ_ONCE(ptemp[i]))
result = -1;
/* Toggle Error bit (it is latched), leave ECC enabled */
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 */
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,
"Read doesn't match written data\n");