nfit/ars: Allow root to busy-poll the ARS state machine (5479b275) · Commits · 戴 / test

The ARS implementation implements exponential back-off on the poll interval to prevent high-frequency access to the DIMM / platform interface. Depending on when the ARS completes the poll interval may exceed the completion event by minutes. Allow root to reset the timeout each time it probes the status. A one-second timeout is still enforced, but root can otherwise can control the poll interval. Fixes: ("nfit, address-range-scrub: rework and simplify ARS...") Cc: <stable@vger.kernel.org> Reported-by:

Erwin Tsaur <erwin.tsaur@oracle.com> Reviewed-by:

Toshi Kani <toshi.kani@hpe.com> Signed-off-by:

Dan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit/core.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1333,6 +1333,13 @@ static ssize_t scrub_show(struct device *dev,
		busy = test_bit(ARS_BUSY, &acpi_desc->scrub_flags)
		&& !test_bit(ARS_CANCEL, &acpi_desc->scrub_flags);
		rc = sprintf(buf, "%d%s", acpi_desc->scrub_count, busy ? "+\n" : "\n");
		/* Allow an admin to poll the busy state at a higher rate */
		if (busy && capable(CAP_SYS_RAWIO) && !test_and_set_bit(ARS_POLL,
		&acpi_desc->scrub_flags)) {
		acpi_desc->scrub_tmo = 1;
		mod_delayed_work(nfit_wq, &acpi_desc->dwork, HZ);
		}

		mutex_unlock(&acpi_desc->init_mutex);
		device_unlock(dev);
		return rc;
		@@ -3187,6 +3194,7 @@ static void acpi_nfit_scrub(struct work_struct *work)
		else
		notify_ars_done(acpi_desc);
		memset(acpi_desc->ars_status, 0, acpi_desc->max_ars);
		clear_bit(ARS_POLL, &acpi_desc->scrub_flags);
		mutex_unlock(&acpi_desc->init_mutex);
		}

drivers/acpi/nfit/nfit.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -213,6 +213,7 @@ struct nfit_mem {
		enum scrub_flags {
		ARS_BUSY,
		ARS_CANCEL,
		ARS_POLL,
		};

		struct acpi_nfit_desc {

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