Fix compile warnings: ignoring return value of 'xenbus_register_backend' ..

We neglect to check the return value of xenbus_register_backend
and take actions when that fails. This patch fixes that and adds
code to deal with those type of failures.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

4 files changed, 22 insertions, 11 deletions

diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index e9e3de119a73..a2ac7189cc0a 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -614,6 +614,7 @@ static void make_response(blkif_t *blkif, u64 id,
 static int __init blkif_init(void)
 {
         int i, mmap_pages;
+        int rc = 0;
 
         if (!xen_pv_domain())
                 return -ENODEV;
@@ -626,13 +627,17 @@ static int __init blkif_init(void)
                                         mmap_pages, GFP_KERNEL);
         pending_pages         = alloc_empty_pages_and_pagevec(mmap_pages);
 
-        if (!pending_reqs || !pending_grant_handles || !pending_pages)
+        if (!pending_reqs || !pending_grant_handles || !pending_pages) {
+                rc = -ENOMEM;
                 goto out_of_memory;
+        }
 
         for (i = 0; i < mmap_pages; i++)
                 pending_grant_handles[i] = BLKBACK_INVALID_HANDLE;
 
-        blkif_interface_init();
+        rc = blkif_interface_init();
+        if (rc)
+                goto failed_init;
 
         memset(pending_reqs, 0, sizeof(pending_reqs));
         INIT_LIST_HEAD(&pending_free);
@@ -640,16 +645,19 @@ static int __init blkif_init(void)
         for (i = 0; i < blkif_reqs; i++)
                 list_add_tail(&pending_reqs[i].free_list, &pending_free);
 
-        blkif_xenbus_init();
+        rc = blkif_xenbus_init();
+        if (rc)
+                goto failed_init;
 
         return 0;
 
  out_of_memory:
+        printk(KERN_ERR "%s: out of memory\n", __func__);
+ failed_init:
         kfree(pending_reqs);
         kfree(pending_grant_handles);
         free_empty_pages_and_pagevec(pending_pages, mmap_pages);
-        printk("%s: out of memory\n", __FUNCTION__);
-        return -ENOMEM;
+        return rc;
 }
 
 module_init(blkif_init);
diff --git a/drivers/xen/blkback/common.h b/drivers/xen/blkback/common.h
index 57b78250cfb7..aaf36485bc01 100644
--- a/drivers/xen/blkback/common.h
+++ b/drivers/xen/blkback/common.h
@@ -124,9 +124,9 @@ struct phys_req {
 
 int vbd_translate(struct phys_req *req, blkif_t *blkif, int operation);
 
-void blkif_interface_init(void);
+int blkif_interface_init(void);
 
-void blkif_xenbus_init(void);
+int blkif_xenbus_init(void);
 
 irqreturn_t blkif_be_int(int irq, void *dev_id);
 int blkif_schedule(void *arg);
diff --git a/drivers/xen/blkback/interface.c b/drivers/xen/blkback/interface.c
index c6c3e14776b9..e397a4134f1b 100644
--- a/drivers/xen/blkback/interface.c
+++ b/drivers/xen/blkback/interface.c
@@ -175,8 +175,12 @@ void blkif_free(blkif_t *blkif)
         kmem_cache_free(blkif_cachep, blkif);
 }
 
-void __init blkif_interface_init(void)
+int __init blkif_interface_init(void)
 {
         blkif_cachep = kmem_cache_create("blkif_cache", sizeof(blkif_t),
                                          0, 0, NULL);
+        if (!blkif_cachep)
+                return -ENOMEM;
+
+        return 0;
 }
diff --git a/drivers/xen/blkback/xenbus.c b/drivers/xen/blkback/xenbus.c
index 650f4b3e9b3c..04c0a12aff36 100644
--- a/drivers/xen/blkback/xenbus.c
+++ b/drivers/xen/blkback/xenbus.c
@@ -535,8 +535,7 @@ static struct xenbus_driver blkback = {
 };
 
 
-void blkif_xenbus_init(void)
+int blkif_xenbus_init(void)
 {
-        /* XXX must_check */
-        (void)xenbus_register_backend(&blkback);
+        return xenbus_register_backend(&blkback);
 }