cxlflash: Fix host link up event handling

Following a link up event, the LUNs available to the host may
have changed. Without rescanning the host, the LUN topology is
unknown to the user. In such a state, the user would be unable
to locate provisioned resources.

To remedy, the host should be rescanned after a link up event.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

drivers/scsi/cxlflash/common.h

@@ -102,6 +102,7 @@ struct cxlflash_cfg {
 	enum cxlflash_init_state init_state;
 	enum cxlflash_lr_state lr_state;
 	int lr_port;
+	atomic_t scan_host_needed;
 
 	struct cxl_afu *cxl_afu;
 

drivers/scsi/cxlflash/main.c

@@ -1119,17 +1119,17 @@ static const struct asyc_intr_info ainfo[] = {
 	{SISL_ASTATUS_FC0_CRC_T, "CRC threshold exceeded", 0, LINK_RESET},
 	{SISL_ASTATUS_FC0_LOGI_R, "login timed out, retrying", 0, 0},
 	{SISL_ASTATUS_FC0_LOGI_F, "login failed", 0, CLR_FC_ERROR},
-	{SISL_ASTATUS_FC0_LOGI_S, "login succeeded", 0, 0},
+	{SISL_ASTATUS_FC0_LOGI_S, "login succeeded", 0, SCAN_HOST},
 	{SISL_ASTATUS_FC0_LINK_DN, "link down", 0, 0},
-	{SISL_ASTATUS_FC0_LINK_UP, "link up", 0, 0},
+	{SISL_ASTATUS_FC0_LINK_UP, "link up", 0, SCAN_HOST},
 	{SISL_ASTATUS_FC1_OTHER, "other error", 1, CLR_FC_ERROR | LINK_RESET},
 	{SISL_ASTATUS_FC1_LOGO, "target initiated LOGO", 1, 0},
 	{SISL_ASTATUS_FC1_CRC_T, "CRC threshold exceeded", 1, LINK_RESET},
 	{SISL_ASTATUS_FC1_LOGI_R, "login timed out, retrying", 1, 0},
 	{SISL_ASTATUS_FC1_LOGI_F, "login failed", 1, CLR_FC_ERROR},
-	{SISL_ASTATUS_FC1_LOGI_S, "login succeeded", 1, 0},
+	{SISL_ASTATUS_FC1_LOGI_S, "login succeeded", 1, SCAN_HOST},
 	{SISL_ASTATUS_FC1_LINK_DN, "link down", 1, 0},
-	{SISL_ASTATUS_FC1_LINK_UP, "link up", 1, 0},
+	{SISL_ASTATUS_FC1_LINK_UP, "link up", 1, SCAN_HOST},
 	{0x0, "", 0, 0}		/* terminator */
 };
 
@@ -1350,6 +1350,11 @@ static irqreturn_t cxlflash_async_err_irq(int irq, void *data)
 			writeq_be(reg, &global->fc_regs[port][FC_ERROR / 8]);
 			writeq_be(0, &global->fc_regs[port][FC_ERRCAP / 8]);
 		}
+
+		if (info->action & SCAN_HOST) {
+			atomic_inc(&cfg->scan_host_needed);
+			schedule_work(&cfg->work_q);
+		}
 	}
 
 out:
@@ -2309,6 +2314,7 @@ MODULE_DEVICE_TABLE(pci, cxlflash_pci_table);
  * - Link reset which cannot be performed on interrupt context due to
  * blocking up to a few seconds
  * - Read AFU command room
+ * - Rescan the host
  */
 static void cxlflash_worker_thread(struct work_struct *work)
 {
@@ -2351,6 +2357,9 @@ static void cxlflash_worker_thread(struct work_struct *work)
 	}
 
 	spin_unlock_irqrestore(cfg->host->host_lock, lock_flags);
+
+	if (atomic_dec_if_positive(&cfg->scan_host_needed) >= 0)
+		scsi_scan_host(cfg->host);
 }
 
 /**

drivers/scsi/cxlflash/main.h

@@ -99,6 +99,7 @@ struct asyc_intr_info {
 	u8 action;
 #define CLR_FC_ERROR	0x01
 #define LINK_RESET	0x02
+#define SCAN_HOST	0x04
 };
 
 #ifndef CONFIG_CXL_EEH