From: Manfred Schlaegl <manfred.schlaegl@ginzinger.com>
To: Wolfgang Grandegger <wg@grandegger.com>,
Marc Kleine-Budde <mkl@pengutronix.de>,
"David S. Miller" <davem@davemloft.net>
Cc: <linux-can@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH] Revert "can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb"
Date: Wed, 19 Dec 2018 19:39:58 +0100 [thread overview]
Message-ID: <eaac34af-7058-e434-7d39-7cb221e5ea88@ginzinger.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 2401 bytes --]
This reverts commit 7da11ba5c5066dadc2e96835a6233d56d7b7764a.
After introduction of this change we encountered following new error
message on various i.MX plattforms (flexcan)
flexcan 53fc8000.can can0: __can_get_echo_skb: BUG! Trying to echo non
existing skb: can_priv::echo_skb[0]
The introduction of the message was a mistake because
priv->echo_skb[idx] = NULL is a perfectly valid in following case:
If CAN_RAW_LOOPBACK is disabled (setsockopt) in applications, the
pkt_type of the tx skb's given to can_put_echo_skb is set to
PACKET_LOOPBACK. In this case can_put_echo_skb will not set
priv->echo_skb[idx]. It is therefore kept NULL.
(As additional argument for revert: The order of check and usage of idx
was changed. idx is used to access an array element before checking it's
boundaries)
Signed-off-by: Manfred Schlaegl <manfred.schlaegl@ginzinger.com>
---
drivers/net/can/dev.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 3b3f88ffab53..c05e4d50d43d 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -480,8 +480,6 @@ EXPORT_SYMBOL_GPL(can_put_echo_skb);
struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr)
{
struct can_priv *priv = netdev_priv(dev);
- struct sk_buff *skb = priv->echo_skb[idx];
- struct canfd_frame *cf;
if (idx >= priv->echo_skb_max) {
netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
@@ -489,20 +487,21 @@ struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8
return NULL;
}
- if (!skb) {
- netdev_err(dev, "%s: BUG! Trying to echo non existing skb: can_priv::echo_skb[%u]\n",
- __func__, idx);
- return NULL;
- }
+ if (priv->echo_skb[idx]) {
+ /* Using "struct canfd_frame::len" for the frame
+ * length is supported on both CAN and CANFD frames.
+ */
+ struct sk_buff *skb = priv->echo_skb[idx];
+ struct canfd_frame *cf = (struct canfd_frame *)skb->data;
+ u8 len = cf->len;
- /* Using "struct canfd_frame::len" for the frame
- * length is supported on both CAN and CANFD frames.
- */
- cf = (struct canfd_frame *)skb->data;
- *len_ptr = cf->len;
- priv->echo_skb[idx] = NULL;
+ *len_ptr = len;
+ priv->echo_skb[idx] = NULL;
- return skb;
+ return skb;
+ }
+
+ return NULL;
}
/*
--
2.11.0
[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 3614 bytes --]
next reply other threads:[~2018-12-19 18:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-19 18:39 Manfred Schlaegl [this message]
2019-01-04 15:23 ` [PATCH] Revert "can: dev: __can_get_echo_skb(): print error message, if trying to echo non existing skb" Marc Kleine-Budde
2019-01-07 8:50 ` Manfred Schlaegl
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=eaac34af-7058-e434-7d39-7cb221e5ea88@ginzinger.com \
--to=manfred.schlaegl@ginzinger.com \
--cc=davem@davemloft.net \
--cc=linux-can@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mkl@pengutronix.de \
--cc=netdev@vger.kernel.org \
--cc=wg@grandegger.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).