[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>

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index fed0b02ebc1d35ecba7c19b534956edf939eb7a6..3fdbb13e80a8ffa95a822ef30eb12a5cef7a5082 100644 (file)
--- 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 c6a904a45bf9871677e50ea762ceaf3c468ae049..82f7b2dd08a23e934aa4d6e08ce76e3c84ab1dc4 100644 (file)
--- 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 257e097c39afe708e2e5a4286948e0de246c5c92..f26299dfc5d5d01d7c0db27f92f1c9e987f5708a 100644 (file)
--- 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 043c3921164ff781f3b20e51232ee091d2381622..0ce5f7cdfe2a182a1e4216377e58476b6e2f1809 100644 (file)
--- 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;