netdev - [PATCH] can: pch_can: initialize errc before using it

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Date:   Fri, 22 Jul 2022 01:00:32 +0900
From:   Vincent Mailhol <mailhol.vincent@...adoo.fr>
To:     Nathan Chancellor <nathan@...nel.org>, linux-can@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        kernel@...gutronix.de, Marc Kleine-Budde <mkl@...gutronix.de>,
        Frank Jungclaus <frank.jungclaus@....eu>,
        Stefan Mätje <Stefan.Maetje@....eu>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>
Subject: [PATCH] can: pch_can: initialize errc before using it

After commit 3a5c7e4611dd, the variable errc is accessed before being
initialized, c.f. below W=2 warning:

| In function 'pch_can_error',
|     inlined from 'pch_can_poll' at drivers/net/can/pch_can.c:739:4:
| drivers/net/can/pch_can.c:501:29: warning: 'errc' may be used uninitialized [-Wmaybe-uninitialized]
|   501 |                 cf->data[6] = errc & PCH_TEC;
|       |                             ^
| drivers/net/can/pch_can.c: In function 'pch_can_poll':
| drivers/net/can/pch_can.c:484:13: note: 'errc' was declared here
|   484 |         u32 errc, lec;
|       |             ^~~~

Moving errc initialization up solves this issue.

Fixes: 3a5c7e4611dd ("can: pch_can: do not report txerr and rxerr during bus-off")
Reported-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
---
 drivers/net/can/pch_can.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c
index 50f6719b3aa4..32804fed116c 100644
--- a/drivers/net/can/pch_can.c
+++ b/drivers/net/can/pch_can.c
@@ -489,6 +489,7 @@ static void pch_can_error(struct net_device *ndev, u32 status)
 	if (!skb)
 		return;
 
+	errc = ioread32(&priv->regs->errc);
 	if (status & PCH_BUS_OFF) {
 		pch_can_set_tx_all(priv, 0);
 		pch_can_set_rx_all(priv, 0);
@@ -502,7 +503,6 @@ static void pch_can_error(struct net_device *ndev, u32 status)
 		cf->data[7] = (errc & PCH_REC) >> 8;
 	}
 
-	errc = ioread32(&priv->regs->errc);
 	/* Warning interrupt. */
 	if (status & PCH_EWARN) {
 		state = CAN_STATE_ERROR_WARNING;
-- 
2.35.1