Re: [PATCH 5/7] ath6kl: convert ath6kl_info/err/warn macros to real functions

[Kalle Valo <kvalo@qca.qualcomm.com>]

Johannes Berg <johannes@sipsolutions.net> writes:

> On Thu, 2012-12-27 at 13:44 +0200, Kalle Valo wrote:
>
>> +	va_start(args, fmt);
>> +	vaf.va = &args;
>> +	ret = ath6kl_printk(KERN_WARNING, "%pV", &vaf);
>> +	va_end(args);
>
> Note that by inserting the tracing here later, you're relying on the
> fact that "%pV" does va_copy(). This isn't true in all kernel versions,
> I think there's on version or so where %pV is supported but didn't
> va_copy(). That may lead to problems (I don't remember what kind) here.
>
> This is relevant for compat only, I think I carry a patch there to add
> va_copy() into the tracing or something.

Compat-drivers has 55-iwlwifi-msg-trace-fix.patch which says:

"In recent kernels, %pV will copy the va_list before using it.
This isn't true for all kernels, so copy the va_list for use
by the dev_*() functions, otherwise the kernel will crash if
the message is printed and traced."

I take it that the problem happens when the message is both printed and
traced at the same time. So ath6kl will need a similar patch as well.

Thanks for the heads up.

Kalle