5 files changed, 58 insertions, 53 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 21fb97b01dd6..3dde8a35493f 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -726,17 +726,16 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
 
         scsi_device_unbusy(sdev);
 
-        /*
-         * Clear the flags which say that the device/host is no longer
-         * capable of accepting new commands.  These are set in scsi_queue.c
-         * for both the queue full condition on a device, and for a
-         * host full condition on the host.
-         *
-         * XXX(hch): What about locking?
-         */
-        shost->host_blocked = 0;
-        starget->target_blocked = 0;
-        sdev->device_blocked = 0;
+        /*
+         * Clear the flags that say that the device/target/host is no longer
+         * capable of accepting new commands.
+         */
+        if (atomic_read(&shost->host_blocked))
+                atomic_set(&shost->host_blocked, 0);
+        if (atomic_read(&starget->target_blocked))
+                atomic_set(&starget->target_blocked, 0);
+        if (atomic_read(&sdev->device_blocked))
+                atomic_set(&sdev->device_blocked, 0);
 
         /*
          * If we have valid sense information, then some kind of recovery
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1ddf0fb43b59..69da4cb5cb13 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -99,14 +99,16 @@ scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
          */
         switch (reason) {
         case SCSI_MLQUEUE_HOST_BUSY:
-                host->host_blocked = host->max_host_blocked;
+                atomic_set(&host->host_blocked, host->max_host_blocked);
                 break;
         case SCSI_MLQUEUE_DEVICE_BUSY:
         case SCSI_MLQUEUE_EH_RETRY:
-                device->device_blocked = device->max_device_blocked;
+                atomic_set(&device->device_blocked,
+                           device->max_device_blocked);
                 break;
         case SCSI_MLQUEUE_TARGET_BUSY:
-                starget->target_blocked = starget->max_target_blocked;
+                atomic_set(&starget->target_blocked,
+                           starget->max_target_blocked);
                 break;
         }
 }
@@ -351,29 +353,35 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev)
         spin_unlock_irqrestore(shost->host_lock, flags);
 }
 
-static inline int scsi_device_is_busy(struct scsi_device *sdev)
+static inline bool scsi_device_is_busy(struct scsi_device *sdev)
 {
-        if (atomic_read(&sdev->device_busy) >= sdev->queue_depth ||
-            sdev->device_blocked)
-                return 1;
-        return 0;
+        if (atomic_read(&sdev->device_busy) >= sdev->queue_depth)
+                return true;
+        if (atomic_read(&sdev->device_blocked) > 0)
+                return true;
+        return false;
 }
 
-static inline int scsi_target_is_busy(struct scsi_target *starget)
+static inline bool scsi_target_is_busy(struct scsi_target *starget)
 {
-        return ((starget->can_queue > 0 &&
-                 atomic_read(&starget->target_busy) >= starget->can_queue) ||
-                 starget->target_blocked);
+        if (starget->can_queue > 0 &&
+            atomic_read(&starget->target_busy) >= starget->can_queue)
+                return true;
+        if (atomic_read(&starget->target_blocked) > 0)
+                return true;
+        return false;
 }
 
-static inline int scsi_host_is_busy(struct Scsi_Host *shost)
+static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
 {
-        if ((shost->can_queue > 0 &&
-             atomic_read(&shost->host_busy) >= shost->can_queue) ||
-            shost->host_blocked || shost->host_self_blocked)
-                return 1;
-
-        return 0;
+        if (shost->can_queue > 0 &&
+            atomic_read(&shost->host_busy) >= shost->can_queue)
+                return true;
+        if (atomic_read(&shost->host_blocked) > 0)
+                return true;
+        if (shost->host_self_blocked)
+                return true;
+        return false;
 }
 
 static void scsi_starved_list_run(struct Scsi_Host *shost)
@@ -1256,14 +1264,14 @@ static inline int scsi_dev_queue_ready(struct request_queue *q,
         unsigned int busy;
 
         busy = atomic_inc_return(&sdev->device_busy) - 1;
-        if (sdev->device_blocked) {
+        if (atomic_read(&sdev->device_blocked)) {
                 if (busy)
                         goto out_dec;
 
                 /*
                  * unblock after device_blocked iterates to zero
                  */
-                if (--sdev->device_blocked != 0) {
+                if (atomic_dec_return(&sdev->device_blocked) > 0) {
                         blk_delay_queue(q, SCSI_QUEUE_DELAY);
                         goto out_dec;
                 }
@@ -1302,19 +1310,15 @@ static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
         }
 
         busy = atomic_inc_return(&starget->target_busy) - 1;
-        if (starget->target_blocked) {
+        if (atomic_read(&starget->target_blocked) > 0) {
                 if (busy)
                         goto starved;
 
                 /*
                  * unblock after target_blocked iterates to zero
                  */
-                spin_lock_irq(shost->host_lock);
-                if (--starget->target_blocked != 0) {
-                        spin_unlock_irq(shost->host_lock);
+                if (atomic_dec_return(&starget->target_blocked) > 0)
                         goto out_dec;
-                }
-                spin_unlock_irq(shost->host_lock);
 
                 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
                                  "unblocking target at zero depth\n"));
@@ -1349,19 +1353,15 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
                 return 0;
 
         busy = atomic_inc_return(&shost->host_busy) - 1;
-        if (shost->host_blocked) {
+        if (atomic_read(&shost->host_blocked) > 0) {
                 if (busy)
                         goto starved;
 
                 /*
                  * unblock after host_blocked iterates to zero
                  */
-                spin_lock_irq(shost->host_lock);
-                if (--shost->host_blocked != 0) {
-                        spin_unlock_irq(shost->host_lock);
+                if (atomic_dec_return(&shost->host_blocked) > 0)
                         goto out_dec;
-                }
-                spin_unlock_irq(shost->host_lock);
 
                 SCSI_LOG_MLQUEUE(3,
                         shost_printk(KERN_INFO, shost,
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 79df9847edef..209cae3097ea 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -584,7 +584,6 @@ static int scsi_sdev_check_buf_bit(const char *buf)
 /*
  * Create the actual show/store functions and data structures.
  */
-sdev_rd_attr (device_blocked, "%d\n");
 sdev_rd_attr (type, "%d\n");
 sdev_rd_attr (scsi_level, "%d\n");
 sdev_rd_attr (vendor, "%.8s\n");
@@ -600,6 +599,15 @@ sdev_show_device_busy(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR(device_busy, S_IRUGO, sdev_show_device_busy, NULL);
 
+static ssize_t
+sdev_show_device_blocked(struct device *dev, struct device_attribute *attr,
+                char *buf)
+{
+        struct scsi_device *sdev = to_scsi_device(dev);
+        return snprintf(buf, 20, "%d\n", atomic_read(&sdev->device_blocked));
+}
+static DEVICE_ATTR(device_blocked, S_IRUGO, sdev_show_device_blocked, NULL);
+
 /*
  * TODO: can we make these symlinks to the block layer ones?
  */
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 3329901c7243..0f853f2c9dc7 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -82,6 +82,8 @@ struct scsi_device {
         struct list_head    same_target_siblings; /* just the devices sharing same target id */
 
         atomic_t device_busy;           /* commands actually active on LLDD */
+        atomic_t device_blocked;        /* Device returned QUEUE_FULL. */
+
         spinlock_t list_lock;
         struct list_head cmd_list;      /* queue of in use SCSI Command structures */
         struct list_head starved_entry;
@@ -180,8 +182,6 @@ struct scsi_device {
         struct list_head event_list;    /* asserted events */
         struct work_struct event_work;
 
-        unsigned int device_blocked;    /* Device returned QUEUE_FULL. */
-
         unsigned int max_device_blocked; /* what device_blocked counts down from  */
 #define SCSI_DEFAULT_DEVICE_BLOCKED     3
 
@@ -291,12 +291,13 @@ struct scsi_target {
                                                  * the same target will also. */
         /* commands actually active on LLD. */
         atomic_t                target_busy;
+        atomic_t                target_blocked;
+
         /*
          * LLDs should set this in the slave_alloc host template callout.
          * If set to zero then there is not limit.
          */
         unsigned int            can_queue;
-        unsigned int            target_blocked;
         unsigned int            max_target_blocked;
 #define SCSI_DEFAULT_TARGET_BLOCKED     3
 
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 51f7911b1cbb..5e8ebc1ac12b 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -583,6 +583,8 @@ struct Scsi_Host {
         struct blk_queue_tag    *bqt;
 
         atomic_t host_busy;                /* commands actually active on low-level */
+        atomic_t host_blocked;
+
         unsigned int host_failed;          /* commands that failed.
                                               protected by host_lock */
         unsigned int host_eh_scheduled;    /* EH scheduled without command */
@@ -682,11 +684,6 @@ struct Scsi_Host {
         struct workqueue_struct *tmf_work_q;
 
         /*
-         * Host has rejected a command because it was busy.
-         */
-        unsigned int host_blocked;
-
-        /*
          * Value host_blocked counts down from
          */
         unsigned int max_host_blocked;