tpm: vtpm_proxy: conditionally call tpm_chip_unregister

If tpm_chip_register fails vtpm must not call tpm_chip_unregister:

> [   58.271017]  [<ffffffff8155bd32>] dpm_sysfs_remove+0x22/0x60
> [   58.271017]  [<ffffffff8154e438>] device_del+0x58/0x280
> [   58.271017]  [<ffffffffa024c020>] tpm_chip_unregister+0x40/0xb0 [tpm]
> [   58.271017]  [<ffffffffa0292360>] vtpm_proxy_fops_release+0x40/0x60 [tpm_vtpm_proxy]

[jarkko.sakkinen@linux.intel.com: cleaned up unneeded goto away]

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Tested-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

drivers/char/tpm/tpm_vtpm_proxy.c

@@ -42,6 +42,7 @@ struct proxy_dev {
 	long state;                  /* internal state */
 #define STATE_OPENED_FLAG        BIT(0)
 #define STATE_WAIT_RESPONSE_FLAG BIT(1)  /* waiting for emulator response */
+#define STATE_REGISTERED_FLAG	 BIT(2)
 
 	size_t req_len;              /* length of queued TPM request */
 	size_t resp_len;             /* length of queued TPM response */
@@ -370,12 +371,9 @@ static void vtpm_proxy_work(struct work_struct *work)
 
 	rc = tpm_chip_register(proxy_dev->chip);
 	if (rc)
-		goto err;
-
-	return;
-
-err:
-	vtpm_proxy_fops_undo_open(proxy_dev);
+		vtpm_proxy_fops_undo_open(proxy_dev);
+	else
+		proxy_dev->state |= STATE_REGISTERED_FLAG;
 }
 
 /*
@@ -516,7 +514,8 @@ static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
 	 */
 	vtpm_proxy_fops_undo_open(proxy_dev);
 
-	tpm_chip_unregister(proxy_dev->chip);
+	if (proxy_dev->state & STATE_REGISTERED_FLAG)
+		tpm_chip_unregister(proxy_dev->chip);
 
 	vtpm_proxy_delete_proxy_dev(proxy_dev);
 }