From: Bart Van Assche <bart.vanassche@sandisk.com>
To: Dragan Stancevic <dragan.stancevic@canonical.com>
Cc: device-mapper development <dm-devel@redhat.com>
Subject: Re: [PATCH 6/6] multipathd: Remove a busy-waiting loop
Date: Wed, 17 Aug 2016 12:55:47 -0700 [thread overview]
Message-ID: <dad032b7-bef9-dfbd-2b18-c4861784277e@sandisk.com> (raw)
In-Reply-To: <CAAZtj80UaRfO_iKOVp8MP4xkXwRwfT5d_hggZmCW4P6ZN2Kjag@mail.gmail.com>
On 08/17/2016 12:42 PM, Dragan Stancevic wrote:
> Hi Bart-
>
> are the semantics below really safe, the don't appear to? Any caller of
> checker_thread_running is relaying on stale information. The
> c->thread_running could have changed as soon as you unlock.
>
> +static unsigned checker_thread_running(struct tur_checker_context *ct)
> +{
> +unsigned thread_running;
> +
> +pthread_spin_lock(&ct->hldr_lock);
> +thread_running = ct->thread_running;
> +pthread_spin_unlock(&ct->hldr_lock);
> +
> +return thread_running;
> +}
Hello Dragan,
If you have a look at libcheck_check() in tur.c then you will see that
it is harmless if checker_thread_running() returns old information.
Bart.
next prev parent reply other threads:[~2016-08-17 19:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-15 15:24 [PATCH 0/7] multipathd: Fix race conditions related to thread termination Bart Van Assche
2016-08-15 15:25 ` [PATCH 1/6] libmultipath: Remove a data structure that has been commented out Bart Van Assche
2016-08-15 15:26 ` [PATCH 2/6] libmultipath: Remove debugging code from lock.h Bart Van Assche
2016-08-15 15:26 ` [PATCH 3/6] libmultipath: Convert lock() and unlock() into inline functions Bart Van Assche
2016-08-15 15:27 ` [PATCH 4/6] libmultipath: Inline mutex in struct mutex_lock Bart Van Assche
2016-08-15 15:27 ` [PATCH 5/6] libmultipath: Introduce timedlock() Bart Van Assche
2016-08-15 15:28 ` [PATCH 6/6] multipathd: Remove a busy-waiting loop Bart Van Assche
2016-08-16 6:31 ` Hannes Reinecke
2016-08-16 20:11 ` Bart Van Assche
2016-08-17 14:44 ` Hannes Reinecke
2016-08-17 15:37 ` Bart Van Assche
2016-08-17 19:42 ` Dragan Stancevic
2016-08-17 19:55 ` Bart Van Assche [this message]
2016-08-25 3:33 ` Benjamin Marzinski
2016-08-26 14:04 ` Hannes Reinecke
2016-08-17 19:36 ` Dragan Stancevic
2016-08-17 19:57 ` Bart Van Assche
2016-08-18 20:54 ` Dragan Stancevic
2016-08-18 22:42 ` Bart Van Assche
2016-08-15 15:29 ` [PATCH 0/7] multipathd: Fix race conditions related to thread termination Bart Van Assche
2016-08-16 7:38 ` Christophe Varoqui
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