target: Convert se_device statistics to atomic_long_t

This patch converts the handful of se_device statistics to type
atomic_long_t, instead of using se_device->stats_lock when
incrementing these values.

More importantly, go ahead and drop the spinlock usage within
transport_lookup_cmd_lun() fast-path code.

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index dbe40ef..986afd2 100644 (file)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -130,15 +130,12 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
        /* Directly associate cmd with se_dev */
        se_cmd->se_dev = se_lun->lun_se_dev;
 
-       /* TODO: get rid of this and use atomics for stats */
        dev = se_lun->lun_se_dev;
-       spin_lock_irqsave(&dev->stats_lock, flags);
-       dev->num_cmds++;
+       atomic_long_inc(&dev->num_cmds);
        if (se_cmd->data_direction == DMA_TO_DEVICE)
-               dev->write_bytes += se_cmd->data_length;
+               atomic_long_add(se_cmd->data_length, &dev->write_bytes);
        else if (se_cmd->data_direction == DMA_FROM_DEVICE)
-               dev->read_bytes += se_cmd->data_length;
-       spin_unlock_irqrestore(&dev->stats_lock, flags);
+               atomic_long_add(se_cmd->data_length, &dev->read_bytes);
 
        return 0;
 }
@@ -1426,7 +1423,6 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
        INIT_LIST_HEAD(&dev->state_list);
        INIT_LIST_HEAD(&dev->qf_cmd_list);
        INIT_LIST_HEAD(&dev->g_dev_node);
-       spin_lock_init(&dev->stats_lock);
        spin_lock_init(&dev->execute_task_lock);
        spin_lock_init(&dev->delayed_cmd_lock);
        spin_lock_init(&dev->dev_reservation_lock);

diff --git a/drivers/target/target_core_stat.c b/drivers/target/target_core_stat.c
index 632665c..0353899 100644 (file)
--- a/drivers/target/target_core_stat.c
+++ b/drivers/target/target_core_stat.c
@@ -213,7 +213,8 @@ static ssize_t target_stat_scsi_tgt_dev_show_attr_resets(
        struct se_device *dev =
                container_of(sgrps, struct se_device, dev_stat_grps);
 
-       return snprintf(page, PAGE_SIZE, "%u\n", dev->num_resets);
+       return snprintf(page, PAGE_SIZE, "%lu\n",
+                       atomic_long_read(&dev->num_resets));
 }
 DEV_STAT_SCSI_TGT_DEV_ATTR_RO(resets);
 
@@ -396,8 +397,8 @@ static ssize_t target_stat_scsi_lu_show_attr_num_cmds(
                container_of(sgrps, struct se_device, dev_stat_grps);
 
        /* scsiLuNumCommands */
-       return snprintf(page, PAGE_SIZE, "%llu\n",
-                       (unsigned long long)dev->num_cmds);
+       return snprintf(page, PAGE_SIZE, "%lu\n",
+                       atomic_long_read(&dev->num_cmds));
 }
 DEV_STAT_SCSI_LU_ATTR_RO(num_cmds);
 
@@ -408,7 +409,8 @@ static ssize_t target_stat_scsi_lu_show_attr_read_mbytes(
                container_of(sgrps, struct se_device, dev_stat_grps);
 
        /* scsiLuReadMegaBytes */
-       return snprintf(page, PAGE_SIZE, "%u\n", (u32)(dev->read_bytes >> 20));
+       return snprintf(page, PAGE_SIZE, "%lu\n",
+                       atomic_long_read(&dev->read_bytes) >> 20);
 }
 DEV_STAT_SCSI_LU_ATTR_RO(read_mbytes);
 
@@ -419,7 +421,8 @@ static ssize_t target_stat_scsi_lu_show_attr_write_mbytes(
                container_of(sgrps, struct se_device, dev_stat_grps);
 
        /* scsiLuWrittenMegaBytes */
-       return snprintf(page, PAGE_SIZE, "%u\n", (u32)(dev->write_bytes >> 20));
+       return snprintf(page, PAGE_SIZE, "%lu\n",
+                       atomic_long_read(&dev->write_bytes) >> 20);
 }
 DEV_STAT_SCSI_LU_ATTR_RO(write_mbytes);
 
@@ -430,7 +433,7 @@ static ssize_t target_stat_scsi_lu_show_attr_resets(
                container_of(sgrps, struct se_device, dev_stat_grps);
 
        /* scsiLuInResets */
-       return snprintf(page, PAGE_SIZE, "%u\n", dev->num_resets);
+       return snprintf(page, PAGE_SIZE, "%lu\n", atomic_long_read(&dev->num_resets));
 }
 DEV_STAT_SCSI_LU_ATTR_RO(resets);
 

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 2500099..70c638f 100644 (file)
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -386,9 +386,7 @@ int core_tmr_lun_reset(
                pr_debug("LUN_RESET: SCSI-2 Released reservation\n");
        }
 
-       spin_lock_irq(&dev->stats_lock);
-       dev->num_resets++;
-       spin_unlock_irq(&dev->stats_lock);
+       atomic_long_inc(&dev->num_resets);
 
        pr_debug("LUN_RESET: %s for [%s] Complete\n",
                        (preempt_and_abort_list) ? "Preempt" : "TMR",

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 96bf1b0..fab91ba 100644 (file)
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -683,11 +683,10 @@ struct se_device {
        /* Pointer to transport specific device structure */
        u32                     dev_index;
        u64                     creation_time;
-       u32                     num_resets;
-       u64                     num_cmds;
-       u64                     read_bytes;
-       u64                     write_bytes;
-       spinlock_t              stats_lock;
+       atomic_long_t           num_resets;
+       atomic_long_t           num_cmds;
+       atomic_long_t           read_bytes;
+       atomic_long_t           write_bytes;
        /* Active commands on this virtual SE device */
        atomic_t                simple_cmds;
        atomic_t                dev_ordered_id;