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From: Dan Williams <dan.j.williams@intel.com>
To: stable@vger.kernel.org
Cc: Erwin Tsaur <erwin.tsaur@oracle.com>, linux-nvdimm@lists.01.org
Subject: [4.19, 5.0 stable PATCH 3/4] nfit/ars: Allow root to busy-poll the ARS state machine
Date: Mon, 22 Apr 2019 16:08:21 -0700	[thread overview]
Message-ID: <155597450168.2675082.12797199567190628607.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <155597449036.2675082.7035380482732870260.stgit@dwillia2-desk3.amr.corp.intel.com>

commit 5479b2757f26fe9908fc341d105b2097fe820b6f upstream.

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: bc6ba8085842 ("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 ++++++++
 drivers/acpi/nfit/nfit.h |    1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 64308e669250..61d3fd65fbe9 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1335,6 +1335,13 @@ 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;
@@ -3196,6 +3203,7 @@ 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);
 }
 
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index 897ce10192a0..d14bad687fb8 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -213,6 +213,7 @@ struct nfit_mem {
 enum scrub_flags {
 	ARS_BUSY,
 	ARS_CANCEL,
+	ARS_POLL,
 };
 
 struct acpi_nfit_desc {

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WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: stable@vger.kernel.org
Cc: Erwin Tsaur <erwin.tsaur@oracle.com>,
	Toshi Kani <toshi.kani@hpe.com>,
	vishal.l.verma@intel.com, linux-nvdimm@lists.01.org
Subject: [4.19, 5.0 stable PATCH 3/4] nfit/ars: Allow root to busy-poll the ARS state machine
Date: Mon, 22 Apr 2019 16:08:21 -0700	[thread overview]
Message-ID: <155597450168.2675082.12797199567190628607.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <155597449036.2675082.7035380482732870260.stgit@dwillia2-desk3.amr.corp.intel.com>

commit 5479b2757f26fe9908fc341d105b2097fe820b6f upstream.

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: bc6ba8085842 ("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 ++++++++
 drivers/acpi/nfit/nfit.h |    1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 64308e669250..61d3fd65fbe9 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1335,6 +1335,13 @@ 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;
@@ -3196,6 +3203,7 @@ 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);
 }
 
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index 897ce10192a0..d14bad687fb8 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -213,6 +213,7 @@ struct nfit_mem {
 enum scrub_flags {
 	ARS_BUSY,
 	ARS_CANCEL,
+	ARS_POLL,
 };
 
 struct acpi_nfit_desc {


  parent reply	other threads:[~2019-04-22 23:22 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-22 23:08 [4.19, 5.0 stable PATCH 1/4] nfit/ars: Remove ars_start_flags Dan Williams
2019-04-22 23:08 ` Dan Williams
2019-04-22 23:08 ` [4.19, 5.0 stable PATCH 2/4] nfit/ars: Introduce scrub_flags Dan Williams
2019-04-22 23:08   ` Dan Williams
2019-04-22 23:08 ` Dan Williams [this message]
2019-04-22 23:08   ` [4.19, 5.0 stable PATCH 3/4] nfit/ars: Allow root to busy-poll the ARS state machine Dan Williams
2019-04-22 23:08 ` [4.19, 5.0 stable PATCH 4/4] nfit/ars: Avoid stale ARS results Dan Williams
2019-04-22 23:08   ` Dan Williams
2019-04-23 13:24 ` [4.19, 5.0 stable PATCH 1/4] nfit/ars: Remove ars_start_flags Sasha Levin
2019-04-23 13:24   ` Sasha Levin

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