Re: [PATCH] scsi_dh_alua: Fix RCU annotations

[Christoph Hellwig]

On Thu, Dec 01, 2016 at 11:30:50AM -0800, Bart Van Assche wrote:
> This patch avoids that sparse complains about RCU pointer dereferences.

Looks good,

Reviewed-by: Christoph Hellwig 
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[PATCH] scsi_dh_alua: Fix RCU annotations

[Bart Van Assche]

This patch avoids that sparse complains about RCU pointer dereferences.

Signed-off-by: Bart Van Assche 
Cc: Hannes Reinecke 
Cc: tang.junhui 
Cc: 
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 16 +---
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
b/drivers/scsi/device_handler/scsi_dh_alua.c
index 7bb2068..815e648 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -95,7 +95,7 @@ struct alua_port_group {
 
 struct alua_dh_data {
struct list_headnode;
-   struct alua_port_group  *pg;
+   struct alua_port_group __rcu *pg;
int group_id;
spinlock_t  pg_lock;
struct scsi_device  *sdev;
@@ -369,7 +369,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h,
 
/* Check for existing port group references */
spin_lock(>pg_lock);
-   old_pg = h->pg;
+   old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(>pg_lock));
if (old_pg != pg) {
/* port group has changed. Update to new port group */
if (h->pg) {
@@ -388,7 +388,9 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h,
list_add_rcu(>node, >dh_list);
spin_unlock_irqrestore(>lock, flags);
 
-   alua_rtpg_queue(h->pg, sdev, NULL, true);
+   alua_rtpg_queue(rcu_dereference_protected(h->pg,
+ lockdep_is_held(>pg_lock)),
+   sdev, NULL, true);
spin_unlock(>pg_lock);
 
if (old_pg)
@@ -940,7 +942,7 @@ static int alua_initialize(struct scsi_device *sdev, struct 
alua_dh_data *h)
 static int alua_set_params(struct scsi_device *sdev, const char *params)
 {
struct alua_dh_data *h = sdev->handler_data;
-   struct alua_port_group __rcu *pg = NULL;
+   struct alua_port_group *pg = NULL;
unsigned int optimize = 0, argc;
const char *p = params;
int result = SCSI_DH_OK;
@@ -987,7 +989,7 @@ static int alua_activate(struct scsi_device *sdev,
struct alua_dh_data *h = sdev->handler_data;
int err = SCSI_DH_OK;
struct alua_queue_data *qdata;
-   struct alua_port_group __rcu *pg;
+   struct alua_port_group *pg;
 
qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
if (!qdata) {
@@ -1051,7 +1053,7 @@ static void alua_check(struct scsi_device *sdev, bool 
force)
 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
 {
struct alua_dh_data *h = sdev->handler_data;
-   struct alua_port_group __rcu *pg;
+   struct alua_port_group *pg;
unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
int ret = BLKPREP_OK;
 
@@ -1121,7 +1123,7 @@ static void alua_bus_detach(struct scsi_device *sdev)
struct alua_port_group *pg;
 
spin_lock(>pg_lock);
-   pg = h->pg;
+   pg = rcu_dereference_protected(h->pg, lockdep_is_held(>pg_lock));
rcu_assign_pointer(h->pg, NULL);
h->sdev = NULL;
spin_unlock(>pg_lock);
-- 
2.10.2

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