[SCSI] scsi_host_lookup: error returns and NULL pointers

This patch cleans up the behavior of scsi_host_lookup().

The original implementation attempted to use the dual role of
either returning a pointer value, or a negative error code.
User's needed to use IS_ERR() to check the result. Additionally,
the IS_ERR() macro never checks for when a NULL pointer was
returned, so a NULL pointer actually passes with a success case.
Note: scsi_host_get(), used by scsi_host_lookup(), can return
a NULL pointer.

Talk about a mudhole for the unitiated to step into....

This patch converts scsi_host_lookup() to return either NULL
or a valid pointer. The consumers were updated for the change.

Signed-off-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

4 files changed, 10 insertions, 10 deletions

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index fed0b02ebc1d..3fdbb13e80a8 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -464,7 +464,7 @@ static int __scsi_host_match(struct device *dev, void *data)
 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 {
         struct device *cdev;
-        struct Scsi_Host *shost = ERR_PTR(-ENXIO);
+        struct Scsi_Host *shost = NULL;
 
         cdev = class_find_device(&shost_class, NULL, &hostnum,
                                  __scsi_host_match);
diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
index c6a904a45bf9..82f7b2dd08a2 100644
--- a/drivers/scsi/scsi_proc.c
+++ b/drivers/scsi/scsi_proc.c
@@ -259,8 +259,8 @@ static int scsi_add_single_device(uint host, uint channel, uint id, uint lun)
         int error = -ENXIO;
 
         shost = scsi_host_lookup(host);
-        if (IS_ERR(shost))
-                return PTR_ERR(shost);
+        if (!shost)
+                return error;
 
         if (shost->transportt->user_scan)
                 error = shost->transportt->user_scan(shost, channel, id, lun);
@@ -287,8 +287,8 @@ static int scsi_remove_single_device(uint host, uint channel, uint id, uint lun)
         int error = -ENXIO;
 
         shost = scsi_host_lookup(host);
-        if (IS_ERR(shost))
-                return PTR_ERR(shost);
+        if (!shost)
+                return error;
         sdev = scsi_device_lookup(shost, channel, id, lun);
         if (sdev) {
                 scsi_remove_device(sdev);
diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index 257e097c39af..f26299dfc5d5 100644
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -460,7 +460,7 @@ int scsi_tgt_kspace_exec(int host_no, u64 itn_id, int result, u64 tag,
 
         /* TODO: replace with a O(1) alg */
         shost = scsi_host_lookup(host_no);
-        if (IS_ERR(shost)) {
+        if (!shost) {
                 printk(KERN_ERR "Could not find host no %d\n", host_no);
                 return -EINVAL;
         }
@@ -550,7 +550,7 @@ int scsi_tgt_kspace_tsk_mgmt(int host_no, u64 itn_id, u64 mid, int result)
         dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);
 
         shost = scsi_host_lookup(host_no);
-        if (IS_ERR(shost)) {
+        if (!shost) {
                 printk(KERN_ERR "Could not find host no %d\n", host_no);
                 return err;
         }
@@ -603,7 +603,7 @@ int scsi_tgt_kspace_it_nexus_rsp(int host_no, u64 itn_id, int result)
         dprintk("%d %d%llx\n", host_no, result, (unsigned long long)itn_id);
 
         shost = scsi_host_lookup(host_no);
-        if (IS_ERR(shost)) {
+        if (!shost) {
                 printk(KERN_ERR "Could not find host no %d\n", host_no);
                 return err;
         }
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 043c3921164f..0ce5f7cdfe2a 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -1361,7 +1361,7 @@ iscsi_tgt_dscvr(struct iscsi_transport *transport,
                 return -EINVAL;
 
         shost = scsi_host_lookup(ev->u.tgt_dscvr.host_no);
-        if (IS_ERR(shost)) {
+        if (!shost) {
                 printk(KERN_ERR "target discovery could not find host no %u\n",
                        ev->u.tgt_dscvr.host_no);
                 return -ENODEV;
@@ -1387,7 +1387,7 @@ iscsi_set_host_param(struct iscsi_transport *transport,
                 return -ENOSYS;
 
         shost = scsi_host_lookup(ev->u.set_host_param.host_no);
-        if (IS_ERR(shost)) {
+        if (!shost) {
                 printk(KERN_ERR "set_host_param could not find host no %u\n",
                        ev->u.set_host_param.host_no);
                 return -ENODEV;