lkml.org 
[lkml]   [2017]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 02/13] EDAC, altera: kill off ACCESS_ONCE()
From
Date
On 10/09/2017 01:28 PM, Mark Rutland wrote:
> 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>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Thor Thayer <thor.thayer@linux.intel.com>
> ---
> drivers/edac/altera_edac.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c
> index 346c498..11d6419 100644
> --- a/drivers/edac/altera_edac.c
> +++ b/drivers/edac/altera_edac.c
> @@ -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");
>
>

Tested on Cyclone5 and Arria10. Thanks!
Acked-by: Thor Thayer <thor.thayer@linux.intel.com>

\
 
 \ /
  Last update: 2017-10-10 01:09    [W:0.201 / U:0.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site