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SubjectRe: [PATCH] libsas: flush pending destruct work in sas_unregister_domain_devices()
On Thu, Dec 7, 2017 at 2:57 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Thu, Dec 7, 2017 at 5:37 AM, John Garry <john.garry@huawei.com> wrote:
>> On 28/11/2017 17:04, Cong Wang wrote:
>>>
>>> I don't understand, the only caller of sas_unregister_domain_devices()
>>> is sas_deform_port().
>>>
>>
>> And sas_deform_port() may be called from another worker on the same queue,
>> right? As in sas_phye_loss_of_signal()->sas_deform_port()
>
> Oh, good catch! I didn't notice this subtle call path.
>
> Do you have any better idea to fix this? We saw this on 4.9 too.
>

I think we can just cancel the destruct work before calling
sas_port_delete(). This should work even if it is called in
another work.

So does the attached (untested) patch make any sense now?
diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 60de66252fa2..bc512d65e2ca 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -565,6 +565,21 @@ int sas_discover_event(struct asd_sas_port *port, enum discover_event ev)
return 0;
}

+static void sas_cancel_work(struct sas_work *sw)
+{
+ cancel_work_sync(&sw->work);
+}
+
+void sas_cancel_event(struct asd_sas_port *port, enum discover_event ev)
+{
+ struct sas_discovery *disc;
+
+ if (!port)
+ return;
+ disc = &port->disc;
+ sas_cancel_work(&disc->disc_work[ev].work);
+}
+
/**
* sas_init_disc -- initialize the discovery struct in the port
* @port: pointer to struct port
diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index d3c5297c6c89..89e37640e26c 100644
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -219,6 +219,7 @@ void sas_deform_port(struct asd_sas_phy *phy, int gone)

if (port->num_phys == 1) {
sas_unregister_domain_devices(port, gone);
+ sas_cancel_event(port, DISCE_DESTRUCT);
sas_port_delete(port->port);
port->port = NULL;
} else {
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 6df6fe0c2198..5b8a7fadd9b4 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -680,6 +680,7 @@ int sas_ex_revalidate_domain(struct domain_device *);
void sas_unregister_domain_devices(struct asd_sas_port *port, int gone);
void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *);
int sas_discover_event(struct asd_sas_port *, enum discover_event ev);
+void sas_cancel_event(struct asd_sas_port *port, enum discover_event ev);

int sas_discover_sata(struct domain_device *);
int sas_discover_end_dev(struct domain_device *);
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