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From: David Marchand <david.marchand@redhat.com>
To: "Xia, Chenbo" <chenbo.xia@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"stable@dpdk.org" <stable@dpdk.org>,
	 Maxime Coquelin <maxime.coquelin@redhat.com>,
	Yuanhan Liu <yliu@fridaylinux.org>
Subject: Re: [PATCH] vhost: avoid sleeping under mutex
Date: Mon, 15 May 2023 13:22:53 +0200	[thread overview]
Message-ID: <CAJFAV8xM5Bk5EOg01a1xmbZhjt9kQKg_UGx1pS0XUaNfQEr53Q@mail.gmail.com> (raw)
In-Reply-To: <SN6PR11MB3504DE8C692245F2DA1DFE699C749@SN6PR11MB3504.namprd11.prod.outlook.com>

On Thu, May 11, 2023 at 10:10 AM Xia, Chenbo <chenbo.xia@intel.com> wrote:
> > Covscan reported:
> >
> >  2. dpdk-21.11/lib/vhost/socket.c:852: lock_acquire: Calling function
> >       "pthread_mutex_lock" acquires lock "vhost_user.mutex".
> > 23. dpdk-21.11/lib/vhost/socket.c:955: sleep: Call to
> >       "vhost_user_reconnect_init" might sleep while holding lock
> >       "vhost_user.mutex".
> >  #   953|             vsocket->reconnect =
> >       !(flags & RTE_VHOST_USER_NO_RECONNECT);
> >  #   954|             if (vsocket->reconnect && reconn_tid == 0) {
> >  #   955|->                   if (vhost_user_reconnect_init() != 0)
> >  #   956|                             goto out_mutex;
> >  #   957|             }
> >
> > The reason for this warning is that vhost_user_reconnect_init() creates a
> > ctrl thread and calls nanosleep waiting for this thread to be ready,
> > while vhost_user.mutex is taken.
> >
> > Move the call to vhost_user_reconnect_init() out of this mutex.
> >
> > While at it, a pthread_t value should be considered opaque.
> > Instead of relying reconn_tid == 0, use an internal flag in
> > vhost_user_reconnect_init().
>
> Should we make reconn_tid not a global variable anymore then?
> Maybe a static pthread_t in vhost_user_reconnect_init?

Yep, I just sent a v2.
Thanks Chenbo.


-- 
David Marchand


  reply	other threads:[~2023-05-15 11:23 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-22 17:05 David Marchand
2023-05-11  8:10 ` Xia, Chenbo
2023-05-15 11:22   ` David Marchand [this message]
2023-05-15 11:18 ` [PATCH v2] " David Marchand
2023-05-15 15:51   ` Stephen Hemminger

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