[PATCH v1] scsi: Fix sas_user_scan() to handle wildcard and multi-channel scans

[Ranjan Kumar <ranjan.kumar@broadcom.com>]

sas_user_scan() did not fully process wildcard channel
scans (SCAN_WILD_CARD).When a transport-specific user_scan()
callback was present.Only channel 0 would be scanned via user_scan(),
while the remaining channels were skipped, potentially missing devices.

user_scan() invoke updated sas_user_scan() for channel 0,
and if successful,iteratively scan remaining
channels (1 to shost->max_channel) via scsi_scan_host_selected().
This ensures complete wildcard scanning without afftecting
transport-specific scanning behavior.

Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
---
 drivers/scsi/scsi_scan.c          |  2 +-
 drivers/scsi/scsi_transport_sas.c | 61 +++++++++++++++++++++++++------
 2 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 4833b8fe251b..396fcf194b6b 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1899,7 +1899,7 @@ int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
 
 	return 0;
 }
-
+EXPORT_SYMBOL(scsi_scan_host_selected);
 static void scsi_sysfs_add_devices(struct Scsi_Host *shost)
 {
 	struct scsi_device *sdev;
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 351b028ef893..42e79eccf05f 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -40,6 +40,8 @@
 #include <scsi/scsi_transport_sas.h>
 
 #include "scsi_sas_internal.h"
+#include "scsi_priv.h"
+
 struct sas_host_attrs {
 	struct list_head rphy_list;
 	struct mutex lock;
@@ -1683,32 +1685,67 @@ int scsi_is_sas_rphy(const struct device *dev)
 }
 EXPORT_SYMBOL(scsi_is_sas_rphy);
 
-
-/*
- * SCSI scan helper
- */
-
-static int sas_user_scan(struct Scsi_Host *shost, uint channel,
-		uint id, u64 lun)
+static void scan_channel_zero(struct Scsi_Host *shost, uint id, u64 lun)
 {
 	struct sas_host_attrs *sas_host = to_sas_host_attrs(shost);
 	struct sas_rphy *rphy;
 
-	mutex_lock(&sas_host->lock);
 	list_for_each_entry(rphy, &sas_host->rphy_list, list) {
 		if (rphy->identify.device_type != SAS_END_DEVICE ||
 		    rphy->scsi_target_id == -1)
 			continue;
 
-		if ((channel == SCAN_WILD_CARD || channel == 0) &&
-		    (id == SCAN_WILD_CARD || id == rphy->scsi_target_id)) {
+		if (id == SCAN_WILD_CARD || id == rphy->scsi_target_id) {
 			scsi_scan_target(&rphy->dev, 0, rphy->scsi_target_id,
 					 lun, SCSI_SCAN_MANUAL);
 		}
 	}
-	mutex_unlock(&sas_host->lock);
+}
 
-	return 0;
+/*
+ * SCSI scan helper
+ */
+
+static int sas_user_scan(struct Scsi_Host *shost, uint channel,
+		uint id, u64 lun)
+{
+	struct sas_host_attrs *sas_host = to_sas_host_attrs(shost);
+	int res = 0;
+	int i;
+
+	switch (channel) {
+	case 0:
+		mutex_lock(&sas_host->lock);
+		scan_channel_zero(shost, id, lun);
+		mutex_unlock(&sas_host->lock);
+		break;
+
+	case SCAN_WILD_CARD:
+
+		mutex_lock(&sas_host->lock);
+		scan_channel_zero(shost, id, lun);
+		mutex_unlock(&sas_host->lock);
+
+		for (i = 1; i <= shost->max_channel; i++) {
+			res = scsi_scan_host_selected(shost, i, id, lun,
+						      SCSI_SCAN_MANUAL);
+			if (res)
+				goto exit_scan;
+		}
+		break;
+
+	default:
+		if (channel < shost->max_channel) {
+			res = scsi_scan_host_selected(shost, channel, id, lun,
+						      SCSI_SCAN_MANUAL);
+		} else {
+			res = -EINVAL;
+		}
+		break;
+	}
+
+exit_scan:
+	return res;
 }
 
 
-- 
2.31.1