linux-kernel - Re: [PATCH v3] cgroup: Add pids controller event when fork fails because of pid limit

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Message-ID: <20160621172832.GM3262@mtj.duckdns.org>
Date:	Tue, 21 Jun 2016 13:28:32 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Kenny Yu <kennyyu@...com>
Cc:	"lizefan@...wei.com" <lizefan@...wei.com>,
	"hannes@...xchg.org" <hannes@...xchg.org>,
	"cyphar@...har.com" <cyphar@...har.com>,
	"cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH v3] cgroup: Add pids controller event when fork fails
 because of pid limit

Hello,

On Tue, Jun 21, 2016 at 05:23:40PM +0000, Kenny Yu wrote:
> >It'd be better to use atomic64_inc_and_test() instead.
> >
> >	if (err) {
> >		if (atomic64_inc_and_test()) {
> >			pr_xxx...;
> >		}
> >		cgroup_file_notify(&pids->events_file);
> >	}
> >
> 
> According to the docs https://www.kernel.org/doc/Documentation/atomic_ops.txt ,
> it looks like atomic_inc_and_test returns "a boolean indicating whether the resulting
> counter value was zero or not", which will only happen when the counter goes from
> negative to 0. I'll keep it as atomic_inc_return and get rid of the temp variable.

Right you're.  Sorry about the confusion.  Yeah, that sounds good to
me.

Thanks!

-- 
tejun