staging: dgnc: implement proper error handling in dgnc_start()

dgnc_start() ignores errors in class_create() and device_create()
and it does not deallocate resources if dgnc_tty_preinit() fails.

The patch implements proper error handling.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/dgnc/dgnc_driver.c b/drivers/staging/dgnc/dgnc_driver.c
index ba98ff348112032314a6124c5d8d2f300388ef1d..f610ae1f3a9ff1fe47b2d32c8b25e6464864f281 100644 (file)
--- a/drivers/staging/dgnc/dgnc_driver.c
+++ b/drivers/staging/dgnc/dgnc_driver.c
@@ -238,6 +238,7 @@ static int dgnc_start(void)
 {
        int rc = 0;
        unsigned long flags;
+       struct device *dev;
 
        /* make sure that the globals are init'd before we do anything else */
        dgnc_init_globals();
@@ -257,9 +258,20 @@ static int dgnc_start(void)
        dgnc_Major = rc;
 
        dgnc_class = class_create(THIS_MODULE, "dgnc_mgmt");
-       device_create(dgnc_class, NULL,
-               MKDEV(dgnc_Major, 0),
-               NULL, "dgnc_mgmt");
+       if (IS_ERR(dgnc_class)) {
+               rc = PTR_ERR(dgnc_class);
+               pr_err(DRVSTR ": Can't create dgnc_mgmt class (%d)\n", rc);
+               goto failed_class;
+       }
+
+       dev = device_create(dgnc_class, NULL,
+                       MKDEV(dgnc_Major, 0),
+                       NULL, "dgnc_mgmt");
+       if (IS_ERR(dev)) {
+               rc = PTR_ERR(dev);
+               pr_err(DRVSTR ": Can't create device (%d)\n", rc);
+               goto failed_device;
+       }
 
        /*
         * Init any global tty stuff.
@@ -268,7 +280,7 @@ static int dgnc_start(void)
 
        if (rc < 0) {
                pr_err(DRVSTR ": tty preinit - not enough memory (%d)\n", rc);
-               return rc;
+               goto failed_tty;
        }
 
        /* Start the poller */
@@ -282,6 +294,14 @@ static int dgnc_start(void)
 
        add_timer(&dgnc_poll_timer);
 
+       return 0;
+
+failed_tty:
+       device_destroy(dgnc_class, MKDEV(dgnc_Major, 0));
+failed_device:
+       class_destroy(dgnc_class);
+failed_class:
+       unregister_chrdev(dgnc_Major, "dgnc");
        return rc;
 }