From: Oleg Nesterov <oleg@redhat.com>
To: Waiman Long <Waiman.Long@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, Stas Sergeev <stsp@list.ru>,
linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [PATCH v2] signals: Avoid unnecessary taking of sighand->siglock
Date: Mon, 26 Sep 2016 18:28:31 +0200 [thread overview]
Message-ID: <20160926162831.GB6782@redhat.com> (raw)
In-Reply-To: <1474649774-48834-1-git-send-email-Waiman.Long@hpe.com>
On 09/23, Waiman Long wrote:
>
>
> + /*
> + * In case the signal mask hasn't changed, we won't need to take
> + * the lock. The current blocked mask can be modified by other CPUs.
> + * To be safe, we need to do an atomic read without lock. As a result,
> + * this check will only be done on 64-bit architectures.
> + */
> + if ((_NSIG_WORDS == 1) &&
> + (READ_ONCE(tsk->blocked.sig[0]) == newset->sig[0]))
> + return;
so in case you missed my reply to V1, I still think that the comment is wrong
and you should drop the _NSIG_WORDS check.
Oleg.
prev parent reply other threads:[~2016-09-26 16:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-23 16:56 [PATCH v2] signals: Avoid unnecessary taking of sighand->siglock Waiman Long
2016-09-23 19:43 ` Stas Sergeev
2016-09-26 21:24 ` Waiman Long
2016-09-26 16:28 ` Oleg Nesterov [this message]
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