Re: [Xen-devel] [PATCH] linux/usbback: fix usbstub_exit() placement

[Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>]

Hi,

Jan Beulich wrote:
> Yes, this is what I needed to do there, since I needed to make it return
> a value there, as a result of xenbus_register_backend() becoming
> __must_check. But really your code, even without the __must_check,
> shouldn't ignore failure from xenbus_register_backend().
I added the checking return value of xenbus_register in usbback_init().
I haven't tested, but probably ok.

Signed-off-by: Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>

diff -r ba13757d92ce -r b40bbc96f74c drivers/xen/usbback/usbback.c
--- a/drivers/xen/usbback/usbback.c     Thu Oct 08 15:37:22 2009 +0900
+++ b/drivers/xen/usbback/usbback.c     Fri Oct 16 23:17:17 2009 +0900
@@ -1093,13 +1093,11 @@
 static int __init usbback_init(void)
 {
        int i, mmap_pages;
+       int err = 0;

        if (!is_running_on_xen())
                return -ENODEV;

-       if (usbstub_init())
-               return -ENODEV;
-
        mmap_pages = usbif_reqs * USBIF_MAX_SEGMENTS_PER_REQUEST;
        pending_reqs = kmalloc(sizeof(pending_reqs[0]) *
                        usbif_reqs, GFP_KERNEL);
@@ -1107,8 +1105,10 @@
                        mmap_pages, GFP_KERNEL);
        pending_pages = alloc_empty_pages_and_pagevec(mmap_pages);

-       if (!pending_reqs || !pending_grant_handles || !pending_pages)
-               goto out_of_memory;
+       if (!pending_reqs || !pending_grant_handles || !pending_pages) {
+               err = -ENOMEM;
+               goto out_mem;
+       }

        for (i = 0; i < mmap_pages; i++)
                pending_grant_handles[i] = USBBACK_INVALID_HANDLE;
@@ -1119,16 +1119,23 @@
        for (i = 0; i < usbif_reqs; i++)
                list_add_tail(&pending_reqs[i].free_list, &pending_free);

-       usbback_xenbus_init();
+       err = usbstub_init();
+       if (err)
+               goto out_mem;
+
+       err = usbback_xenbus_init();
+       if (err)
+               goto out_xenbus;

        return 0;

- out_of_memory:
-        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;
+out_xenbus:
+       usbstub_exit();
+out_mem:
+       kfree(pending_reqs);
+       kfree(pending_grant_handles);
+       free_empty_pages_and_pagevec(pending_pages, mmap_pages);
+       return err;
 }

 static void __exit usbback_exit(void)
diff -r ba13757d92ce -r b40bbc96f74c drivers/xen/usbback/usbback.h
--- a/drivers/xen/usbback/usbback.h     Thu Oct 08 15:37:22 2009 +0900
+++ b/drivers/xen/usbback/usbback.h     Fri Oct 16 23:17:17 2009 +0900
@@ -145,7 +145,7 @@
        } while (0)

 usbif_t *find_usbif(domid_t domid, unsigned int handle);
-void usbback_xenbus_init(void);
+int usbback_xenbus_init(void);
 void usbback_xenbus_exit(void);
 struct vusb_port_id *find_portid_by_busid(const char *busid);
 struct vusb_port_id *find_portid(const domid_t domid,
diff -r ba13757d92ce -r b40bbc96f74c drivers/xen/usbback/usbstub.c
--- a/drivers/xen/usbback/usbstub.c     Thu Oct 08 15:37:22 2009 +0900
+++ b/drivers/xen/usbback/usbstub.c     Fri Oct 16 23:17:17 2009 +0900
@@ -317,7 +317,7 @@
        return err;
 }

-void __exit usbstub_exit(void)
+void usbstub_exit(void)
 {
        driver_remove_file(&usbback_usb_driver.driver,
                                &driver_attr_port_ids);
diff -r ba13757d92ce -r b40bbc96f74c drivers/xen/usbback/xenbus.c
--- a/drivers/xen/usbback/xenbus.c      Thu Oct 08 15:37:22 2009 +0900
+++ b/drivers/xen/usbback/xenbus.c      Fri Oct 16 23:17:17 2009 +0900
@@ -327,12 +327,12 @@
        .remove = usbback_remove,
 };

-void usbback_xenbus_init(void)
+int __init usbback_xenbus_init(void)
 {
-       xenbus_register_backend(&usbback_driver);
+       return xenbus_register_backend(&usbback_driver);
 }

-void usbback_xenbus_exit(void)
+void __exit usbback_xenbus_exit(void)
 {
        xenbus_unregister_driver(&usbback_driver);
 }




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