Process the result of hdlc_open() and call uhdlc_close()
in case of an error. It is necessary to pass the error
code up the control flow, similar to a possible
error in request_irq().
Also add a hdlc_close() call to the uhdlc_close()
because the comment to hdlc_close() says it must be called
by the hardware driver when the HDLC device is being closed

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: c19b6d246a35 ("drivers/net: support hdlc function for QE-UCC")
Signed-off-by: Alexandra Diupina <redacted>
---
v4: undo all the things done prior to hdlc_open() as 
Jakub Kicinski [off-list ref] suggested, 
add hdlc_close() call to the uhdlc_close() to match the function comment, 
add uhdlc_close() declaration to the top of the file not to put the 
uhdlc_close() function definition before uhdlc_open()
v3: Fix the commits tree
v2: Remove the 'rc' variable (stores the return value of the 
hdlc_open()) as Christophe Leroy [off-list ref] suggested
 drivers/net/wan/fsl_ucc_hdlc.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wan/fsl_ucc_hdlc.c b/drivers/net/wan/fsl_ucc_hdlc.c
index 47c2ad7a3e42..fd999dabdd39 100644
--- a/drivers/net/wan/fsl_ucc_hdlc.c
+++ b/drivers/net/wan/fsl_ucc_hdlc.c

@@ -34,6 +34,8 @@
 #define TDM_PPPOHT_SLIC_MAXIN
 #define RX_BD_ERRORS (R_CD_S | R_OV_S | R_CR_S | R_AB_S | R_NO_S | R_LG_S)
 
+static int uhdlc_close(struct net_device *dev);
+
 static struct ucc_tdm_info utdm_primary_info = {
 	.uf_info = {
 		.tsa = 0,

@@ -731,7 +733,9 @@ static int uhdlc_open(struct net_device *dev)
 		napi_enable(&priv->napi);
 		netdev_reset_queue(dev);
 		netif_start_queue(dev);
-		hdlc_open(dev);
+
+		int rc = hdlc_open(dev);
+		return rc == 0 ? 0 : (uhdlc_close(dev), rc);
 	}
 
 	return 0;

@@ -824,6 +828,8 @@ static int uhdlc_close(struct net_device *dev)
 	netdev_reset_queue(dev);
 	priv->hdlc_busy = 0;
 
+	hdlc_close(dev);
+
 	return 0;
 }
 

-- 
2.30.2