From: Jens Freimann <jfreimann@redhat.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: yliu@fridaylinux.org, thomas@monjalon.net, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 1/2] vhost: fix deadlock on IOTLB miss
Date: Fri, 13 Oct 2017 13:32:04 +0200 [thread overview]
Message-ID: <20171013113204.hmmkitx6m5ijhduj@dhcp-192-218.str.redhat.com> (raw)
In-Reply-To: <20171012153850.21837-2-maxime.coquelin@redhat.com>
On Thu, Oct 12, 2017 at 03:38:49PM +0000, Maxime Coquelin wrote:
>An optimization was done to only take the iotlb cache lock
>once per packet burst instead of once per IOVA translation.
>
>With this, IOTLB miss requests are sent to Qemu with the lock
>held, which can cause a deadlock if the socket buffer is full,
>and if Qemu is waiting for an IOTLB update to be done.
>
>Holding the lock is not necessary when sending an IOTLB miss
>request, as it is not manipulating the IOTLB cache list, which
>the lock protects. Let's just release it while sending the
>IOTLB miss.
>
>Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>---
> lib/librte_vhost/vhost.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
Seems to be safe, because in case of an IOTLB miss we only take a
different lock.
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
next prev parent reply other threads:[~2017-10-13 11:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171012153850.21837-1-maxime.coquelin@redhat.com>
2017-10-12 15:38 ` Maxime Coquelin
2017-10-13 11:32 ` Jens Freimann [this message]
2017-10-12 15:38 ` [dpdk-dev] [PATCH 2/2] vhost: fix IOTLB on NUMA realloc Maxime Coquelin
2017-10-13 11:23 ` Jens Freimann
2017-10-13 18:37 ` [dpdk-dev] [PATCH 0/2] vhost: IOTLB fixes for -rc1 Thomas Monjalon
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