cdrom: gdrom: initialize global variable at init time

commit 9183f01b5e6e32eb3f17b5f3f8d5ad5ac9786c49 upstream.

As Peter points out, if we were to disconnect and then reconnect this
driver from a device, the "global" state of the device would contain odd
values and could cause problems.  Fix this up by just initializing the
whole thing to 0 at probe() time.

Ideally this would be a per-device variable, but given the age and the
total lack of users of it, that would require a lot of s/./->/g changes
for really no good reason.

Reported-by: Peter Rosin <[email protected]>
Cc: Jens Axboe <[email protected]>
Reviewed-by: Peter Rosin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/cdrom/gdrom.c

@@ -773,6 +773,13 @@ static int probe_gdrom_setupqueue(void)
 static int probe_gdrom(struct platform_device *devptr)
 {
 	int err;
+
+	/*
+	 * Ensure our "one" device is initialized properly in case of previous
+	 * usages of it
+	 */
+	memset(&gd, 0, sizeof(gd));
+
 	/* Start the device */
 	if (gdrom_execute_diagnostic() != 1) {
 		pr_warning("ATA Probe for GDROM failed\n");
@@ -867,7 +874,7 @@ static struct platform_driver gdrom_driver = {
 static int __init init_gdrom(void)
 {
 	int rc;
-	gd.toc = NULL;
+
 	rc = platform_driver_register(&gdrom_driver);
 	if (rc)
 		return rc;