scsi: Protect SCSI device state changes with a mutex

Serializing SCSI device state changes avoids that two state changes can
occur concurrently, e.g. the state changes in scsi_target_block() and
__scsi_remove_device(). This serialization is essential to make patch
"Make __scsi_remove_device go straight from BLOCKED to DEL" work
reliably.

Enable this mechanism for all scsi_target_*block() callers but not for
the scsi_internal_device_unblock() calls from the mpt3sas driver because
that driver can call scsi_internal_device_unblock() from atomic context.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index ecc07dab893dc473c831227e567cddbbb04e1852..ac3196420435ef25e974c34328ce0ddc2764d795 100644 (file)
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1628,11 +1628,17 @@ static void scsi_eh_offline_sdevs(struct list_head *work_q,
                                  struct list_head *done_q)
 {
        struct scsi_cmnd *scmd, *next;
+       struct scsi_device *sdev;
 
        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
                sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
                            "not ready after error recovery\n");
-               scsi_device_set_state(scmd->device, SDEV_OFFLINE);
+               sdev = scmd->device;
+
+               mutex_lock(&sdev->state_mutex);
+               scsi_device_set_state(sdev, SDEV_OFFLINE);
+               mutex_unlock(&sdev->state_mutex);
+
                scsi_eh_finish_cmd(scmd, done_q);
        }
        return;

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f0eb55744513fb9f0cfa49f6c5d2cfec18ce179f..4b0bac3ac6abab4626c0084f7daa742e15c4eb3f 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2882,7 +2882,12 @@ static void scsi_wait_for_queuecommand(struct scsi_device *sdev)
 int
 scsi_device_quiesce(struct scsi_device *sdev)
 {
-       int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
+       int err;
+
+       mutex_lock(&sdev->state_mutex);
+       err = scsi_device_set_state(sdev, SDEV_QUIESCE);
+       mutex_unlock(&sdev->state_mutex);
+
        if (err)
                return err;
 
@@ -2910,10 +2915,11 @@ void scsi_device_resume(struct scsi_device *sdev)
         * so assume the state is being managed elsewhere (for example
         * device deleted during suspend)
         */
-       if (sdev->sdev_state != SDEV_QUIESCE ||
-           scsi_device_set_state(sdev, SDEV_RUNNING))
-               return;
-       scsi_run_queue(sdev->request_queue);
+       mutex_lock(&sdev->state_mutex);
+       if (sdev->sdev_state == SDEV_QUIESCE &&
+           scsi_device_set_state(sdev, SDEV_RUNNING) == 0)
+               scsi_run_queue(sdev->request_queue);
+       mutex_unlock(&sdev->state_mutex);
 }
 EXPORT_SYMBOL(scsi_device_resume);
 
@@ -3012,6 +3018,7 @@ static int scsi_internal_device_block(struct scsi_device *sdev)
        struct request_queue *q = sdev->request_queue;
        int err;
 
+       mutex_lock(&sdev->state_mutex);
        err = scsi_internal_device_block_nowait(sdev);
        if (err == 0) {
                if (q->mq_ops)
@@ -3019,6 +3026,8 @@ static int scsi_internal_device_block(struct scsi_device *sdev)
                else
                        scsi_wait_for_queuecommand(sdev);
        }
+       mutex_unlock(&sdev->state_mutex);
+
        return err;
 }
  
@@ -3089,7 +3098,13 @@ EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
 static int scsi_internal_device_unblock(struct scsi_device *sdev,
                                        enum scsi_device_state new_state)
 {
-       return scsi_internal_device_unblock_nowait(sdev, new_state);
+       int ret;
+
+       mutex_lock(&sdev->state_mutex);
+       ret = scsi_internal_device_unblock_nowait(sdev, new_state);
+       mutex_unlock(&sdev->state_mutex);
+
+       return ret;
 }
 
 static void

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 6f7128f49c30d62d381556275d667c84eda6ab62..e6de4eee97a3e3009d8a12d49c9adfd0a43ecfec 100644 (file)
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -231,6 +231,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
        sdev->id = starget->id;
        sdev->lun = lun;
        sdev->channel = starget->channel;
+       mutex_init(&sdev->state_mutex);
        sdev->sdev_state = SDEV_CREATED;
        INIT_LIST_HEAD(&sdev->siblings);
        INIT_LIST_HEAD(&sdev->same_target_siblings);
@@ -943,16 +944,17 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 
        /* set the device running here so that slave configure
         * may do I/O */
+       mutex_lock(&sdev->state_mutex);
        ret = scsi_device_set_state(sdev, SDEV_RUNNING);
-       if (ret) {
+       if (ret)
                ret = scsi_device_set_state(sdev, SDEV_BLOCK);
+       mutex_unlock(&sdev->state_mutex);
 
-               if (ret) {
-                       sdev_printk(KERN_ERR, sdev,
-                                   "in wrong state %s to complete scan\n",
-                                   scsi_device_state_name(sdev->sdev_state));
-                       return SCSI_SCAN_NO_RESPONSE;
-               }
+       if (ret) {
+               sdev_printk(KERN_ERR, sdev,
+                           "in wrong state %s to complete scan\n",
+                           scsi_device_state_name(sdev->sdev_state));
+               return SCSI_SCAN_NO_RESPONSE;
        }
 
        if (*bflags & BLIST_MS_192_BYTES_FOR_3F)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 82dfe07b1d47f7e1f8ae3517191f15d190168834..a91537a3abbfad3f8e16c638504cc098c51b0cb6 100644 (file)
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -719,7 +719,7 @@ static ssize_t
 store_state_field(struct device *dev, struct device_attribute *attr,
                  const char *buf, size_t count)
 {
-       int i;
+       int i, ret;
        struct scsi_device *sdev = to_scsi_device(dev);
        enum scsi_device_state state = 0;
 
@@ -734,9 +734,11 @@ store_state_field(struct device *dev, struct device_attribute *attr,
        if (!state)
                return -EINVAL;
 
-       if (scsi_device_set_state(sdev, state))
-               return -EINVAL;
-       return count;
+       mutex_lock(&sdev->state_mutex);
+       ret = scsi_device_set_state(sdev, state);
+       mutex_unlock(&sdev->state_mutex);
+
+       return ret == 0 ? count : -EINVAL;
 }
 
 static ssize_t
@@ -1272,6 +1274,7 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 void __scsi_remove_device(struct scsi_device *sdev)
 {
        struct device *dev = &sdev->sdev_gendev;
+       int res;
 
        /*
         * This cleanup path is not reentrant and while it is impossible
@@ -1282,7 +1285,15 @@ void __scsi_remove_device(struct scsi_device *sdev)
                return;
 
        if (sdev->is_visible) {
-               if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0)
+               /*
+                * If scsi_internal_target_block() is running concurrently,
+                * wait until it has finished before changing the device state.
+                */
+               mutex_lock(&sdev->state_mutex);
+               res = scsi_device_set_state(sdev, SDEV_CANCEL);
+               mutex_unlock(&sdev->state_mutex);
+
+               if (res != 0)
                        return;
 
                bsg_unregister_queue(sdev->request_queue);
@@ -1298,7 +1309,10 @@ void __scsi_remove_device(struct scsi_device *sdev)
         * scsi_run_queue() invocations have finished before tearing down the
         * device.
         */
+       mutex_lock(&sdev->state_mutex);
        scsi_device_set_state(sdev, SDEV_DEL);
+       mutex_unlock(&sdev->state_mutex);
+
        blk_cleanup_queue(sdev->request_queue);
        cancel_work_sync(&sdev->requeue_work);
 

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index 3c5d89852e9f0a8ed124444b25fc13f7f1fe937d..f617021c94f740e6dd8fe8ac2526405a4319c6d2 100644 (file)
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -554,11 +554,12 @@ int srp_reconnect_rport(struct srp_rport *rport)
                 * invoking scsi_target_unblock() won't change the state of
                 * these devices into running so do that explicitly.
                 */
-               spin_lock_irq(shost->host_lock);
-               __shost_for_each_device(sdev, shost)
+               shost_for_each_device(sdev, shost) {
+                       mutex_lock(&sdev->state_mutex);
                        if (sdev->sdev_state == SDEV_OFFLINE)
                                sdev->sdev_state = SDEV_RUNNING;
-               spin_unlock_irq(shost->host_lock);
+                       mutex_unlock(&sdev->state_mutex);
+               }
        } else if (rport->state == SRP_RPORT_RUNNING) {
                /*
                 * srp_reconnect_rport() has been invoked with fast_io_fail

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b6bb4e0ce0e3288f321ef1319621063f02d6c868..53b6d72c214d65c7ca3b911c76b66697397f77c5 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1818,8 +1818,9 @@ static void sd_eh_reset(struct scsi_cmnd *scmd)
 static int sd_eh_action(struct scsi_cmnd *scmd, int eh_disp)
 {
        struct scsi_disk *sdkp = scsi_disk(scmd->request->rq_disk);
+       struct scsi_device *sdev = scmd->device;
 
-       if (!scsi_device_online(scmd->device) ||
+       if (!scsi_device_online(sdev) ||
            !scsi_medium_access_command(scmd) ||
            host_byte(scmd->result) != DID_TIME_OUT ||
            eh_disp != SUCCESS)
@@ -1845,7 +1846,9 @@ static int sd_eh_action(struct scsi_cmnd *scmd, int eh_disp)
        if (sdkp->medium_access_timed_out >= sdkp->max_medium_access_timeouts) {
                scmd_printk(KERN_ERR, scmd,
                            "Medium access timeout failure. Offlining disk!\n");
-               scsi_device_set_state(scmd->device, SDEV_OFFLINE);
+               mutex_lock(&sdev->state_mutex);
+               scsi_device_set_state(sdev, SDEV_OFFLINE);
+               mutex_unlock(&sdev->state_mutex);
 
                return SUCCESS;
        }

diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 5f24dae2a8e1185ca5b261d6818fe99b0425a413..d13bc80825b1992b0ecb4af329b6e616e0860a57 100644 (file)
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -207,6 +207,7 @@ struct scsi_device {
        void                    *handler_data;
 
        unsigned char           access_state;
+       struct mutex            state_mutex;
        enum scsi_device_state sdev_state;
        unsigned long           sdev_data[0];
 } __attribute__((aligned(sizeof(unsigned long))));