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acpi, nfit: Fix scrub idle detection 

The notification of scrub completion happens within the scrub workqueue.
That can clearly race someone running scrub_show() and work_busy()
before the workqueue has a chance to flush the recently completed work.
Add a flag to reliably indicate the idle vs busy state. Without this
change applications using poll(2) to wait for scrub-completion may
falsely wakeup and read ARS as being busy even though the thread is
going idle and then hang indefinitely.

Fixes: bc6ba80858 ("nfit, address-range-scrub: rework and simplify ARS...")
Cc: <stable@vger.kernel.org>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Tested-by: Vishal Verma <vishal.l.verma@intel.com>
Reported-by: Lukasz Dorau <lukasz.dorau@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
hifive-unleashed-5.1
Dan Williams 2018-07-05 14:58:49 -07:00
parent 1273c253c3
commit 33cc2c9667
2 changed files with 34 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
drivers/acpi/nfit/core.c
View File

@ -1275,7 +1275,7 @@ static ssize_t scrub_show(struct device *dev,
mutex_lock(&acpi_desc->init_mutex);
rc = sprintf(buf, "%d%s", acpi_desc->scrub_count,
work_busy(&acpi_desc->dwork.work)
acpi_desc->scrub_busy
&& !acpi_desc->cancel ? "+\n" : "\n");
mutex_unlock(&acpi_desc->init_mutex);
}
@ -2941,6 +2941,32 @@ static unsigned int __acpi_nfit_scrub(struct acpi_nfit_desc *acpi_desc,
return 0;
}
static void __sched_ars(struct acpi_nfit_desc *acpi_desc, unsigned int tmo)
{
lockdep_assert_held(&acpi_desc->init_mutex);
acpi_desc->scrub_busy = 1;
/* note this should only be set from within the workqueue */
if (tmo)
acpi_desc->scrub_tmo = tmo;
queue_delayed_work(nfit_wq, &acpi_desc->dwork, tmo * HZ);
}
static void sched_ars(struct acpi_nfit_desc *acpi_desc)
{
__sched_ars(acpi_desc, 0);
}
static void notify_ars_done(struct acpi_nfit_desc *acpi_desc)
{
lockdep_assert_held(&acpi_desc->init_mutex);
acpi_desc->scrub_busy = 0;
acpi_desc->scrub_count++;
if (acpi_desc->scrub_count_state)
sysfs_notify_dirent(acpi_desc->scrub_count_state);
}
static void acpi_nfit_scrub(struct work_struct *work)
{
struct acpi_nfit_desc *acpi_desc;
@ -2951,14 +2977,10 @@ static void acpi_nfit_scrub(struct work_struct *work)
mutex_lock(&acpi_desc->init_mutex);
query_rc = acpi_nfit_query_poison(acpi_desc);
tmo = __acpi_nfit_scrub(acpi_desc, query_rc);
if (tmo) {
queue_delayed_work(nfit_wq, &acpi_desc->dwork, tmo * HZ);
acpi_desc->scrub_tmo = tmo;
} else {
acpi_desc->scrub_count++;
if (acpi_desc->scrub_count_state)
sysfs_notify_dirent(acpi_desc->scrub_count_state);
}
if (tmo)
__sched_ars(acpi_desc, tmo);
else
notify_ars_done(acpi_desc);
memset(acpi_desc->ars_status, 0, acpi_desc->max_ars);
mutex_unlock(&acpi_desc->init_mutex);
}
@ -3039,7 +3061,7 @@ static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc)
break;
}
queue_delayed_work(nfit_wq, &acpi_desc->dwork, 0);
sched_ars(acpi_desc);
return 0;
}
@ -3241,7 +3263,7 @@ int acpi_nfit_ars_rescan(struct acpi_nfit_desc *acpi_desc, unsigned long flags)
}
}
if (scheduled) {
queue_delayed_work(nfit_wq, &acpi_desc->dwork, 0);
sched_ars(acpi_desc);
dev_dbg(dev, "ars_scan triggered\n");
}
mutex_unlock(&acpi_desc->init_mutex);

1
drivers/acpi/nfit/nfit.h
View File

@ -203,6 +203,7 @@ struct acpi_nfit_desc {
unsigned int max_ars;
unsigned int scrub_count;
unsigned int scrub_mode;
unsigned int scrub_busy:1;
unsigned int cancel:1;
unsigned long dimm_cmd_force_en;
unsigned long bus_cmd_force_en;