linux-kernel - Re: [PATCH 02/13] EDAC, altera: kill off ACCESS

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Date:   Tue, 10 Oct 2017 10:30:11 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Thor Thayer <thor.thayer@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 02/13] EDAC, altera: kill off ACCESS_ONCE()

On Mon, Oct 09, 2017 at 06:12:10PM -0500, Thor Thayer wrote:
> On 10/09/2017 01:28 PM, Mark Rutland wrote:
> >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@...ux.intel.com>

Thanks, that's much appreciated!

Mark.