[PATCH v2 1/2] EDAC/device_sysfs: Reject poll_msec value 0

[PATCH v2 1/2] EDAC/device_sysfs: Reject poll_msec value 0

[Jad Keskes]

The poll_msec store allows writing 0, which sets the workqueue delay
to 0 jiffies. This causes the poll work to spin without any delay,
consuming 100% CPU on the polling kworker.

The comment has said "must be at least one millisecond" since the file
was first added, but no validation was ever enforced. Add a check for
value < 1 and return -EINVAL.

Fixes: e27e3dac6517 ("drivers/edac: add edac_device class")
Signed-off-by: Jad Keskes <inasj268@gmail.com>
---
 drivers/edac/edac_device_sysfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/edac/edac_device_sysfs.c b/drivers/edac/edac_device_sysfs.c
index b1c2717cd023..89adfd3091e0 100644
--- a/drivers/edac/edac_device_sysfs.c
+++ b/drivers/edac/edac_device_sysfs.c
@@ -96,6 +96,9 @@ static ssize_t edac_device_ctl_poll_msec_store(struct edac_device_ctl_info
 	 * and set a new one.
 	 */
 	value = simple_strtoul(data, NULL, 0);
+	if (value < 1)
+		return -EINVAL;
+
 	edac_device_reset_delay_period(ctl_info, value);
 
 	return count;
-- 
2.55.0

[PATCH v2 2/2] EDAC/device: Don't re-arm workqueue during teardown

[Jad Keskes]

edac_device_del_device() stops the workqueue then removes the sysfs
attributes.  However, writing to poll_msec triggers
edac_device_reset_delay_period(), which unconditionally re-arms the
workqueue.  If writes occur during that window, the re-armed work
runs after edac_dev has been freed.

Fix this by checking op_state in reset_delay_period().  del_device()
already sets it to OP_OFFLINE before tearing down the workqueue, so
the new guard causes reset_delay_period() to skip mod_work() when
the device is being removed.

Signed-off-by: Jad Keskes <inasj268@gmail.com>
---
 drivers/edac/edac_device.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/edac/edac_device.c b/drivers/edac/edac_device.c
index cf0d3c2dfc04..50ae7f1e5152 100644
--- a/drivers/edac/edac_device.c
+++ b/drivers/edac/edac_device.c
@@ -354,6 +354,10 @@ void edac_device_reset_delay_period(struct edac_device_ctl_info *edac_dev,
 	edac_dev->poll_msec = msec;
 	edac_dev->delay	    = msecs_to_jiffies(msec);
 
+	/* Don't re-arm the workqueue if the device is being torn down */
+	if (edac_dev->op_state == OP_OFFLINE)
+		return;
+
 	/* See comment in edac_device_workq_setup() above */
 	if (edac_dev->poll_msec == DEFAULT_POLL_INTERVAL)
 		edac_mod_work(&edac_dev->work, round_jiffies_relative(edac_dev->delay));
-- 
2.55.0