Re: [PATCH] lib/vsprintf: add %pT format specifier

[Pavel Machek <pavel@ucw.cz>]

On Fri 2014-01-10 17:57:30, Andrew Morton wrote:
> On Sat, 11 Jan 2014 10:28:51 +0900 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> wrote:
> 
> > Andrew Morton wrote:
> > > On Thu, 9 Jan 2014 21:52:00 +0900 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> wrote:
> > > 
> > > > This patch introduces %pT format specifier for printing task_struct->comm.
> > > > Currently %pT does not provide consistency. I'm planning to change to use RCU
> > > > in the future. By using RCU, the comm name read from task_struct->comm will be
> > > > guaranteed to be consistent. But before modifying set_task_comm() to use RCU,
> > > > we need to kill direct ->comm users who do not use get_task_comm().
> > > 
> > > On reflection...
> > > 
> > > It isn't obvious that this patch is sufficiently beneficial until we
> > > have that RCU code in place.
> > > 
> > > So I could retain this patch in -mm until we have that all sorted out. 
> > > And I'll have to avoid merging %pT users into mainline in the
> > > meanwhile!
> > > 
> > > Am I wrong?  The patch seems fairly pointless as a standalone thing?
> > > 
> > 
> >   Step 1: (targeted to 3.14-rc1)
> >     Add "%pT" format specifier and commcpy() wrapper function.
> > 
> >   Step 2: (started after step 1 is reflected to other git trees)
> >     Replace printk("%s", p->comm) with printk("%pT", p).
> >     Replace strcpy(buf, p->comm) with commcpy(buf, p).
> > 
> >   Step 3: (started after step 2 is reflected to other git trees)
> >     Add rcu_read_lock()/rcu_read_unlock() into commcpy().
> >     Modify set_task_comm() etc. to replace ->comm using RCU.
> 
> In the absence of step 3, steps 1 and 2 are rather pointless churn.

Dunno. Given how often it appears in the code, it looks to me like
step 1 is worthwile cleanup on its own...
									Pavel
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