From: Konstantin Shelekhin <k.shelekhin@xxxxxxxxx>
Get rid of spinlock and bump PR generation atomically. This is required
to prevent deadlock later on.
Signed-off-by: Konstantin Shelekhin <k.shelekhin@xxxxxxxxx>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@xxxxxxxxx>
---
drivers/target/target_core_configfs.c | 3 ++-
drivers/target/target_core_pr.c | 25 ++++++-------------------
include/target/target_core_base.h | 2 +-
3 files changed, 9 insertions(+), 21 deletions(-)
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 40b9808738d2..610de251994e 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -1814,7 +1814,8 @@ static ssize_t target_pr_res_pr_all_tgt_pts_show(struct config_item *item,
static ssize_t target_pr_res_pr_generation_show(struct config_item *item,
char *page)
{
- return sprintf(page, "0x%08x\n", pr_to_dev(item)->t10_pr.pr_generation);
+ return sprintf(page, "0x%08x\n",
+ atomic_read(&pr_to_dev(item)->t10_pr.pr_generation));
}
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 668670b1414a..8f3d920d2590 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -594,8 +594,6 @@ target_scsi3_pr_reservation_check(struct se_cmd *cmd)
static u32 core_scsi3_pr_generation(struct se_device *dev)
{
- u32 prg;
-
/*
* PRGeneration field shall contain the value of a 32-bit wrapping
* counter mainted by the device server.
@@ -605,11 +603,7 @@ static u32 core_scsi3_pr_generation(struct se_device *dev)
*
* See spc4r17 section 6.3.12 READ_KEYS service action
*/
- spin_lock(&dev->dev_reservation_lock);
- prg = dev->t10_pr.pr_generation++;
- spin_unlock(&dev->dev_reservation_lock);
-
- return prg;
+ return atomic_inc_return(&dev->t10_pr.pr_generation);
}
static struct t10_pr_registration *__core_scsi3_do_alloc_registration(
@@ -1057,15 +1051,8 @@ static void __core_scsi3_add_registration(
/*
* Increment PRgeneration counter for struct se_device upon a successful
* REGISTER, see spc4r17 section 6.3.2 READ_KEYS service action
- *
- * Also, when register_move = 1 for PROUT REGISTER_AND_MOVE service
- * action, the struct se_device->dev_reservation_lock will already be held,
- * so we do not call core_scsi3_pr_generation() which grabs the lock
- * for the REGISTER.
*/
- pr_reg->pr_res_generation = (register_move) ?
- dev->t10_pr.pr_generation++ :
- core_scsi3_pr_generation(dev);
+ pr_reg->pr_res_generation = core_scsi3_pr_generation(dev);
spin_lock(&pr_tmpl->registration_lock);
list_add_tail(&pr_reg->pr_reg_list, &pr_tmpl->registration_list);
@@ -3481,7 +3468,7 @@ core_scsi3_emulate_pro_register_and_move(struct se_cmd *cmd, u64 res_key,
* Increment PRGeneration for existing registrations..
*/
if (!new_reg)
- dest_pr_reg->pr_res_generation = pr_tmpl->pr_generation++;
+ dest_pr_reg->pr_res_generation = core_scsi3_pr_generation(dev);
spin_unlock(&dev->dev_reservation_lock);
pr_debug("SPC-3 PR [%s] Service Action: REGISTER_AND_MOVE"
@@ -3703,7 +3690,7 @@ core_scsi3_pri_read_keys(struct se_cmd *cmd)
if (!buf)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
- put_unaligned_be32(dev->t10_pr.pr_generation, buf);
+ put_unaligned_be32(atomic_read(&dev->t10_pr.pr_generation), buf);
spin_lock(&dev->t10_pr.registration_lock);
list_for_each_entry(pr_reg, &dev->t10_pr.registration_list,
@@ -3758,7 +3745,7 @@ core_scsi3_pri_read_reservation(struct se_cmd *cmd)
if (!buf)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
- put_unaligned_be32(dev->t10_pr.pr_generation, &buf[0]);
+ put_unaligned_be32(atomic_read(&dev->t10_pr.pr_generation), &buf[0]);
spin_lock(&dev->dev_reservation_lock);
pr_reg = dev->dev_pr_res_holder;
@@ -3900,7 +3887,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
if (!buf)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
- put_unaligned_be32(dev->t10_pr.pr_generation, &buf[0]);
+ put_unaligned_be32(atomic_read(&dev->t10_pr.pr_generation), &buf[0]);
spin_lock(&dev->dev_reservation_lock);
if (dev->dev_pr_res_holder) {
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 6ed484683ab6..7e13db647faa 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -385,7 +385,7 @@ struct t10_reservation {
* for SCSI device */
int pr_aptpl_active;
#define PR_APTPL_BUF_LEN 262144
- u32 pr_generation;
+ atomic_t pr_generation;
spinlock_t registration_lock;
spinlock_t aptpl_reg_lock;
/*
--
2.25.1
