Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm

[Joe Perches <joe@perches.com>]

On Thu, 2011-05-12 at 15:12 -0700, David Rientjes wrote:
> On Tue, 10 May 2011, Joe Perches wrote:
> > > Although I'm not sure if there's precedent for a %p value that didn't
> > > take a argument. Thoughts on that? Anyone else have an opinion here?
> > The uses of %ptc must add an argument or else gcc will complain.
> > I suggest you just ignore the argument value and use current.
> That doesn't make any sense, why would you needlessly restrict this to 
> current when accesses to other threads' ->comm needs to be protected in 
> the same way?  I'd like to use this in the oom killer and try to get rid 
> of taking task_lock() for every thread group leader in the tasklist dump.

I suppose another view is coder stuffed up, let them suffer...

At some point, gcc may let us extend printf argument type
verification so it may not be a continuing problem.

Adding a checkpatch rule for this is non-trivial as it can
be written as:

	printk("%ptc\n",
	       current);

and checkpatch is mostly line oriented.

Andy, do you have a suggestion on how to verify
vsprintf argument types for checkpatch?