From: Ilya Maximets <i.maximets@samsung.com>
To: dev@dpdk.org, Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: Tiwei Bie <tiwei.bie@intel.com>,
Zhihong Wang <zhihong.wang@intel.com>,
jfreimann@redhat.com, Ilya Maximets <i.maximets@samsung.com>,
stable@dpdk.org
Subject: [dpdk-dev] [PATCH] vhost: fix double read of descriptor flags
Date: Wed, 5 Dec 2018 18:09:26 +0300 [thread overview]
Message-ID: <20181205150926.4895-1-i.maximets@samsung.com> (raw)
In-Reply-To: <CGME20181205150935eucas1p11698df8ed58ff02a4326dd5780af4470@eucas1p1.samsung.com>
Flags could be updated in a separate process leading to the
inconsistent check.
Additionally, read marked as 'volatile' to highlight the shared
nature of the variable and avoid such issues in the future.
Fixes: d3211c98c456 ("vhost: add helpers for packed virtqueues")
Cc: stable@dpdk.org
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
---
lib/librte_vhost/vhost.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 5218f1b12..84cbee2b6 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -393,8 +393,10 @@ vq_is_packed(struct virtio_net *dev)
static inline bool
desc_is_avail(struct vring_packed_desc *desc, bool wrap_counter)
{
- return wrap_counter == !!(desc->flags & VRING_DESC_F_AVAIL) &&
- wrap_counter != !!(desc->flags & VRING_DESC_F_USED);
+ uint16_t flags = *((volatile uint16_t *) &desc->flags);
+
+ return wrap_counter == !!(flags & VRING_DESC_F_AVAIL) &&
+ wrap_counter != !!(flags & VRING_DESC_F_USED);
}
#define VHOST_LOG_PAGE 4096
--
2.17.1
next parent reply other threads:[~2018-12-05 15:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20181205150935eucas1p11698df8ed58ff02a4326dd5780af4470@eucas1p1.samsung.com>
2018-12-05 15:09 ` Ilya Maximets [this message]
2018-12-11 14:47 ` Maxime Coquelin
2018-12-11 18:33 ` Maxime Coquelin
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