From: Oleg Nesterov <oleg@redhat.com>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: paulmck@kernel.org, peterz@infradead.org,
linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
madhuparnabhowmik10@gmail.com, joel@joelfernandes.org,
linux-kernel-mentees@lists.linuxfoundation.org, mingo@kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH] exit.c: Fix Sparse errors and warnings
Date: Thu, 30 Jan 2020 12:33:41 +0100 [thread overview]
Message-ID: <20200130113339.GA25426@redhat.com> (raw)
In-Reply-To: <20200130103158.azxldyfnugwvv6vy@wittgenstein>
On 01/30, Christian Brauner wrote:
>
> On Thu, Jan 30, 2020 at 11:50:28AM +0530, madhuparnabhowmik10@gmail.com wrote:
> > From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
> >
> > This patch fixes the following sparse error:
> > kernel/exit.c:627:25: error: incompatible types in comparison expression
> >
> > And the following warning:
> > kernel/exit.c:626:40: warning: incorrect type in assignment
> >
> > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
>
> I think the previous version was already fine but hopefully
> RCU_INIT_POINTER() really saves some overhead. In any case:
It is not about overhead, RCU_INIT_POINTER() documents the fact that we
didn't make any changes to the new parent, we only need to change the
pointer.
And btw, I don't really understand the __rcu annotations. Say, according
to sparse this code is wrong:
int __rcu *P;
void func(int *p)
{
P = p;
}
OK, although quite possibly it is fine.
However, this code
int __rcu *P;
void func(int __rcu *p)
{
*p = 10;
P = p;
}
is almost certainly wrong but sparse is happy, asn is the same.
> Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
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next prev parent reply other threads:[~2020-01-30 11:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 6:20 [Linux-kernel-mentees] [PATCH] exit.c: Fix Sparse errors and warnings madhuparnabhowmik10
2020-01-30 10:31 ` Christian Brauner
2020-01-30 11:33 ` Oleg Nesterov [this message]
2020-01-30 11:45 ` Christian Brauner
2020-01-30 15:20 ` Christian Brauner
-- strict thread matches above, loose matches on Subject: below --
2020-01-28 17:20 madhuparnabhowmik10
2020-01-28 18:01 ` Christian Brauner
2020-01-29 12:30 ` Oleg Nesterov
2020-01-29 16:02 ` Madhuparna Bhowmik
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