Commit 5e8e19bf authored Sep 21, 2011 by Borislav Petkov Committed by Borislav Petkov Mar 19, 2012

EDAC: Correct scrub rate API



The original scrub rate API definition states that if scrub rate
accessors are not implemented, a negative value (-1) should be written
to the sysfs file (/sys/devices/system/edac/mc/mc<N>/sdram_scrub_rate,
where N is the memory controller number on the system). This is
counter-intuitive and awkward at the very least because, when setting
the scrub rate, userspace has to write to sysfs and then read it back to
check error status of the operation.

As Tony notes, best it would be to not have the sdram_scrub_rate in
sysfs if scrub rate support is not implemented. It is too late about
that and a bunch of drivers on a bunch of arches would need to be
changed and tested which is not a trivial task ATM.

Instead, settle for the next best thing of returning -ENODEV when
implementation is missing and -EINVAL when there was an error
encountered while setting the scrub rate.

Reported-by: Han Pingtian <phan@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20110916105856.GA13253@hpt.nay.redhat.com


Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

parent 11b0a314

Documentation/edac.txt

+2 −2

Original line number	Diff line number	Diff line
		@@ -334,8 +334,8 @@ Sdram memory scrubbing rate:

		Reading the file will return the actual scrubbing rate employed.

		If configuration fails or memory scrubbing is not implemented, the value
		of the attribute file will be -1.
		If configuration fails or memory scrubbing is not implemented, accessing
		that attribute will fail.

drivers/edac/edac_mc_sysfs.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -452,7 +452,7 @@ static ssize_t mci_sdram_scrub_rate_store(struct mem_ctl_info *mci,
		int new_bw = 0;

		if (!mci->set_sdram_scrub_rate)
		return -EINVAL;
		return -ENODEV;

		if (strict_strtoul(data, 10, &bandwidth) < 0)
		return -EINVAL;
		@@ -475,7 +475,7 @@ static ssize_t mci_sdram_scrub_rate_show(struct mem_ctl_info mci, char data)
		int bandwidth = 0;

		if (!mci->get_sdram_scrub_rate)
		return -EINVAL;
		return -ENODEV;

		bandwidth = mci->get_sdram_scrub_rate(mci);
		if (bandwidth < 0) {

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