From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Dan Murphy <dmurphy@ti.com>, wg@grandegger.com, davem@davemloft.net
Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 1/5] can: m_can: Create a m_can platform framework
Date: Thu, 9 May 2019 08:38:29 +0200 [thread overview]
Message-ID: <b6d6daab-ff49-76d1-e363-6179100be560@pengutronix.de> (raw)
In-Reply-To: <35d179a7-2682-111e-638b-903559f0974a@ti.com>
[-- Attachment #1.1: Type: text/plain, Size: 2404 bytes --]
On 5/8/19 9:54 PM, Dan Murphy wrote:
>>> -/* m_can private data structure */
>>> -struct m_can_priv {
>>> - struct can_priv can; /* must be the first member */
>>> - struct napi_struct napi;
>>> - struct net_device *dev;
>>> - struct device *device;
>>> - struct clk *hclk;
>>> - struct clk *cclk;
>>> - void __iomem *base;
>>> - u32 irqstatus;
>>> - int version;
>>> -
>>> - /* message ram configuration */
>>> - void __iomem *mram_base;
>>> - struct mram_cfg mcfg[MRAM_CFG_NUM];
>>> -};
>>> +static u32 m_can_read(struct m_can_priv *priv, enum m_can_reg reg)
>>> +{
>>> + if (priv->ops->read_reg)
>>> + return priv->ops->read_reg(priv, reg);
>>> + else
>>> + return -EINVAL;
>>> +}
>>
>> How do you plan to check the return value here?
>> What's the difference between a register value of 0xffffffe9 and
>> returning -EINVAL?
>
> Good point. I could just inline this and return whatever is sent
> from the callback and as you said allow a backtrace to happen if
> read_reg is invalid.
ACK.
A minimal function will look like this:
static inline u32 m_can_read(struct m_can_priv *priv, enum m_can_reg reg)
{
return priv->ops->read_reg(priv, reg);
}
And of ops or read_reg is NULL, the kernel will access a NULL pointer
that would then generate a backtrace.
>>> -static inline u32 m_can_read(const struct m_can_priv *priv, enum m_can_reg reg)
>>> +static int m_can_write(struct m_can_priv *priv, enum m_can_reg reg, u32 val)
>>> {
>>> - return readl(priv->base + reg);
>>> + if (priv->ops->write_reg)
>>> + return priv->ops->write_reg(priv, reg, val);
>>> + else
>>> + return -EINVAL;
>>> }
>>
>> I don't see anyone checking the return value. Better just dereference
>> the pointer and the kernel will produce a nice backtrace.
>>
>> Same should be done for all read and write variants.
>>
>
> I will need to go through this and see if there is any caller checking the return. But
> I think you are correct. If thats true I will just change this to a void, inline the function
> and allow a backtrace if the callback is null
ok
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
prev parent reply other threads:[~2019-05-09 6:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 17:26 [PATCH v11 1/5] can: m_can: Create a m_can platform framework Dan Murphy
2019-03-19 17:26 ` [PATCH v11 2/5] can: m_can: Rename m_can_priv to m_can_classdev Dan Murphy
2019-03-19 17:26 ` [PATCH v11 3/5] dt-bindings: can: tcan4x5x: Add DT bindings for TCAN4x5X driver Dan Murphy
2019-03-19 17:26 ` [PATCH v11 4/5] can: tcan4x5x: Add tcan4x5x driver to the kernel Dan Murphy
2019-03-19 17:26 ` [PATCH v11 5/5] can: m_can: Fix checkpatch issues on existing code Dan Murphy
2019-04-02 12:03 ` [PATCH v11 1/5] can: m_can: Create a m_can platform framework Dan Murphy
2019-04-02 12:17 ` Wolfgang Grandegger
2019-04-10 13:24 ` Dan Murphy
2019-04-18 14:36 ` Dan Murphy
2019-05-01 14:10 ` Dan Murphy
2019-05-08 14:35 ` Marc Kleine-Budde
2019-05-08 19:54 ` Dan Murphy
2019-05-09 6:38 ` Marc Kleine-Budde [this message]
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=b6d6daab-ff49-76d1-e363-6179100be560@pengutronix.de \
--to=mkl@pengutronix.de \
--cc=davem@davemloft.net \
--cc=dmurphy@ti.com \
--cc=linux-can@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--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).