This patch implements a VPD page rescan if the 'rescan' sysfs
attribute is triggered.

Signed-off-by: Hannes Reinecke <[email protected]>
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 11 +++++++----
 drivers/scsi/scsi.c                        | 20 +++++++++++++++++---
 drivers/scsi/scsi_scan.c                   |  4 ++++
 drivers/scsi/scsi_sysfs.c                  |  8 ++++++--
 drivers/scsi/ses.c                         |  6 ++++--
 include/scsi/scsi_device.h                 |  1 +
 6 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
b/drivers/scsi/device_handler/scsi_dh_alua.c
index d077014..e4cabc8 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -264,8 +264,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h)
        int device_id_size, device_id_type = 0;
        struct alua_port_group *tmp_pg, *pg = NULL;
 
-       if (!sdev->vpd_pg83)
+       rcu_read_lock();
+       if (!rcu_dereference(sdev->vpd_pg83)) {
+               rcu_read_unlock();
                return SCSI_DH_DEV_UNSUPP;
+       }
 
        /*
         * Look for the correct descriptor.
@@ -281,8 +284,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h)
         */
        memset(device_id_str, 0, 256);
        device_id_size = 0;
-       d = sdev->vpd_pg83 + 4;
-       while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
+       d = rcu_dereference(sdev->vpd_pg83) + 4;
+       while (d < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) {
                switch (d[1] & 0xf) {
                case 0x2:
                        /* EUI-64 */
@@ -366,7 +369,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h)
                }
                d += d[3] + 4;
        }
-
+       rcu_read_unlock();
        if (group_id == -1) {
                /*
                 * Internal error; TPGS supported but required
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 207d6a7..f1c0fb5 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -803,7 +803,7 @@ void scsi_attach_vpd(struct scsi_device *sdev)
        int vpd_len = SCSI_VPD_PG_LEN;
        int pg80_supported = 0;
        int pg83_supported = 0;
-       unsigned char *vpd_buf;
+       unsigned char *vpd_buf, *orig_vpd_buf = NULL;
 
        if (sdev->skip_vpd_pages)
                return;
@@ -849,8 +849,16 @@ retry_pg80:
                        kfree(vpd_buf);
                        goto retry_pg80;
                }
+               mutex_lock(&sdev->inquiry_mutex);
+               orig_vpd_buf = sdev->vpd_pg80;
                sdev->vpd_pg80_len = result;
-               sdev->vpd_pg80 = vpd_buf;
+               rcu_assign_pointer(sdev->vpd_pg80, vpd_buf);
+               mutex_unlock(&sdev->inquiry_mutex);
+               synchronize_rcu();
+               if (orig_vpd_buf) {
+                       kfree(orig_vpd_buf);
+                       orig_vpd_buf = NULL;
+               }
                vpd_len = SCSI_VPD_PG_LEN;
        }
 
@@ -870,8 +878,14 @@ retry_pg83:
                        kfree(vpd_buf);
                        goto retry_pg83;
                }
+               mutex_lock(&sdev->inquiry_mutex);
+               orig_vpd_buf = sdev->vpd_pg83;
                sdev->vpd_pg83_len = result;
-               sdev->vpd_pg83 = vpd_buf;
+               rcu_assign_pointer(sdev->vpd_pg83, vpd_buf);
+               mutex_unlock(&sdev->inquiry_mutex);
+               synchronize_rcu();
+               if (orig_vpd_buf)
+                       kfree(orig_vpd_buf);
        }
 }
 
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index f9f3f82..190d743 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -235,6 +235,7 @@ static struct scsi_device *scsi_alloc_sdev(struct 
scsi_target *starget,
        INIT_LIST_HEAD(&sdev->starved_entry);
        INIT_LIST_HEAD(&sdev->event_list);
        spin_lock_init(&sdev->list_lock);
+       mutex_init(&sdev->inquiry_mutex);
        INIT_WORK(&sdev->event_work, scsi_evt_thread);
        INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue);
 
@@ -1516,6 +1517,9 @@ EXPORT_SYMBOL(scsi_add_device);
 void scsi_rescan_device(struct device *dev)
 {
        device_lock(dev);
+
+       scsi_attach_vpd(to_scsi_device(dev));
+
        if (dev->driver && try_module_get(dev->driver->owner)) {
                struct scsi_driver *drv = to_scsi_driver(dev->driver);
 
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index e3c3b86..b4de776 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -759,11 +759,15 @@ show_vpd_##_page(struct file *filp, struct kobject *kobj, 
\
 {                                                                      \
        struct device *dev = container_of(kobj, struct device, kobj);   \
        struct scsi_device *sdev = to_scsi_device(dev);                 \
+       int ret;                                                        \
        if (!sdev->vpd_##_page)                                         \
                return -EINVAL;                                         \
-       return memory_read_from_buffer(buf, count, &off,                \
-                                      sdev->vpd_##_page,               \
+       rcu_read_lock();                                                \
+       ret = memory_read_from_buffer(buf, count, &off,                 \
+                                     rcu_dereference(sdev->vpd_##_page), \
                                       sdev->vpd_##_page##_len);        \
+       rcu_read_unlock();                                              \
+       return ret;                                             \
 }                                                                      \
 static struct bin_attribute dev_attr_vpd_##_page = {           \
        .attr = {.name = __stringify(vpd_##_page), .mode = S_IRUGO },   \
diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index dcb0d76..1fc372e 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -563,8 +563,9 @@ static void ses_match_to_enclosure(struct enclosure_device 
*edev,
        if (!sdev->vpd_pg83_len)
                return;
 
-       desc = sdev->vpd_pg83 + 4;
-       while (desc < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
+       rcu_read_lock();
+       desc = rcu_dereference(sdev->vpd_pg83) + 4;
+       while (desc < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) {
                enum scsi_protocol proto = desc[0] >> 4;
                u8 code_set = desc[0] & 0x0f;
                u8 piv = desc[1] & 0x80;
@@ -578,6 +579,7 @@ static void ses_match_to_enclosure(struct enclosure_device 
*edev,
 
                desc += len + 4;
        }
+       rcu_read_unlock();
        if (efd.addr) {
                efd.dev = &sdev->sdev_gendev;
 
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 2725f8f..d2f8b7a 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -109,6 +109,7 @@ struct scsi_device {
        char type;
        char scsi_level;
        char inq_periph_qual;   /* PQ from INQUIRY data */      
+       struct mutex inquiry_mutex;
        unsigned char inquiry_len;      /* valid bytes in 'inquiry' */
        unsigned char * inquiry;        /* INQUIRY response data */
        const char * vendor;            /* [back_compat] point into 'inquiry' 
... */
-- 
1.8.5.2

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