[PATCH] scsi: alua: Fix alua_rtpg_queue()

Bart Van Assche
2022-11-15T22:49:49Z

Modify alua_rtpg_queue() such that it only requests the caller to drop
the sdev reference if necessary. This patch fixes a recently introduced
regression.

Cc: Sachin Sant <sachinp@linux.ibm.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin Wilck <mwilck@suse.com>
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Fixes: 0b25e17e9018 ("scsi: alua: Move a scsi_device_put() call out of alua_check_vpd()")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 31 ++++++++++++++--------
1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 693cd827e138..c1bf75673e89 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -102,7 +102,7 @@ struct alua_queue_data {

static void alua_rtpg_work(struct work_struct *work);
static bool alua_rtpg_queue(struct alua_port_group *pg,
- struct scsi_device *sdev,
+ struct scsi_device *sdev, bool *put_sdev,
struct alua_queue_data *qdata, bool force);
static void alua_check(struct scsi_device *sdev, bool force);

@@ -374,9 +374,9 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
list_add_rcu(&h->node, &pg->dh_list);
spin_unlock_irqrestore(&pg->lock, flags);

- put_sdev = alua_rtpg_queue(rcu_dereference_protected(h->pg,
+ alua_rtpg_queue(rcu_dereference_protected(h->pg,
lockdep_is_held(&h->pg_lock)),
- sdev, NULL, true);
+ sdev, &put_sdev, NULL, true);
spin_unlock(&h->pg_lock);

if (put_sdev)
@@ -983,17 +983,23 @@ static void alua_rtpg_work(struct work_struct *work)
*
* Returns true if and only if alua_rtpg_work() will be called asynchronously.
* That function is responsible for calling @qdata->fn(). If this function
- * returns true, the caller is responsible for invoking scsi_device_put(@sdev).
+ * sets *put_sdev to true, the caller is responsible for calling
+ * scsi_device_put(@sdev).
*/
-static bool __must_check alua_rtpg_queue(struct alua_port_group *pg,
- struct scsi_device *sdev,
+static bool alua_rtpg_queue(struct alua_port_group *pg,
+ struct scsi_device *sdev, bool *put_sdev,
struct alua_queue_data *qdata, bool force)
{
int start_queue = 0;
unsigned long flags;
+
+ *put_sdev = false;
+
if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
return false;

+ *put_sdev = true;
+
spin_lock_irqsave(&pg->lock, flags);
if (qdata) {
list_add_tail(&qdata->entry, &pg->rtpg_list);
@@ -1020,7 +1026,7 @@ static bool __must_check alua_rtpg_queue(struct alua_port_group *pg,
if (start_queue) {
if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
- sdev = NULL;
+ *put_sdev = false;
else
kref_put(&pg->kref, release_port_group);
}
@@ -1108,6 +1114,7 @@ static int alua_activate(struct scsi_device *sdev,
int err = SCSI_DH_OK;
struct alua_queue_data *qdata;
struct alua_port_group *pg;
+ bool put_sdev;

qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
if (!qdata) {
@@ -1130,8 +1137,9 @@ static int alua_activate(struct scsi_device *sdev,
rcu_read_unlock();
mutex_unlock(&h->init_mutex);

- if (alua_rtpg_queue(pg, sdev, qdata, true)) {
- scsi_device_put(sdev);
+ if (alua_rtpg_queue(pg, sdev, &put_sdev, qdata, true)) {
+ if (put_sdev)
+ scsi_device_put(sdev);
fn = NULL;
} else {
err = SCSI_DH_DEV_OFFLINED;
@@ -1153,6 +1161,7 @@ static void alua_check(struct scsi_device *sdev, bool force)
{
struct alua_dh_data *h = sdev->handler_data;
struct alua_port_group *pg;
+ bool put_sdev;

rcu_read_lock();
pg = rcu_dereference(h->pg);
@@ -1161,8 +1170,8 @@ static void alua_check(struct scsi_device *sdev, bool force)
return;
}
rcu_read_unlock();
-
- if (alua_rtpg_queue(pg, sdev, NULL, force))
+ alua_rtpg_queue(pg, sdev, &put_sdev, NULL, force);
+ if (put_sdev)
scsi_device_put(sdev);
kref_put(&pg->kref, release_port_group);
}