On Wed, Jul 11, 2012 at 5:01 PM, Joe Perches <[email protected]> wrote:
> On Wed, 2012-07-11 at 12:33 +0200, Kay Sievers wrote:
> Interesting idea, perhaps workable, but it has
> a few defects I can see.
>
> It works for most uses, but it doesn't work for
> when there are multiple function sites like
>
> void dump_info(struct foo *bar)
> {
> if (bar->baz)
> pr_cont("baz...");
> }
>
> ---
>
> pr_info("Some initiator: ")
> dump_info(&descriptor);
Yeah, it's just the common case, not for the "creative" ones. :)
> Another negative is that is uses a local stack
> variable for the entire line which increases
> stack pressure.
The thing is to avoid malloc(), and ~100 bytes are kind of OK for the
time we do the printk, I guess
> It also fails to immediately output after some
> defect unlike your change to output directly to
> console.
Which is really only that important for stuff that causes crashes
between the outputting fragments.
There are _many_ cases the console lock is held, and we don't print
stuff immediately out to the console, and we never ensured that in the
past. There was never a guarantee that stuff ended up on the console,
kmsg was always and needs to be a store+forward model.
> It would require all sites with continuation lines
> be modified. Because it requires in-situ code
> modifications, I'd prefer a cookie based approach.
Well, it would be mostly for the dev_printk() stuff, which should
ideally never be merged with stuff that could go wrong.
> I think it's more flexible, allows the cookie to be
> passed into extending functions and doesn't demand
> (much) extra stack.
>
> Something like:
> https://lkml.org/lkml/2012/4/3/231
> https://lkml.org/lkml/2011/11/14/349
Hmm, how do we manage memory allocations here? We can get around that
somehow? It's something the common printk() must really avoid.
Kay
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