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From: Laurent Vivier <lvivier@redhat.com>
To: passt-dev@passt.top
Cc: Laurent Vivier <lvivier@redhat.com>
Subject: [PATCH 4/8] udp_vu: Make virtqueue buffers stack-local for thread safety
Date: Tue, 16 Jun 2026 19:10:48 +0200	[thread overview]
Message-ID: <20260616171052.3785909-5-lvivier@redhat.com> (raw)
In-Reply-To: <20260616171052.3785909-1-lvivier@redhat.com>

The function-local static buffers elem[] and iov_vu[] in
udp_vu_sock_to_tap() are shared across all threads. When multiple
worker threads process UDP vhost-user data concurrently, they would
stomp on each other's buffers.

Remove the static qualifier so each call gets its own stack-allocated
arrays, eliminating cross-thread sharing.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 udp_vu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/udp_vu.c b/udp_vu.c
index 864e7a99b8d9..342673dc7e6d 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -146,8 +146,8 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx,
 {
 	const struct flowside *toside = flowside_at_sidx(tosidx);
 	bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
-	static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
-	static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE];
+	struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
+	struct iovec iov_vu[VIRTQUEUE_MAX_SIZE];
 	int rx_queue = QPAIR_TOGUEST_QUEUE(qpair);
 	struct vu_dev *vdev = c->vdev;
 	struct vu_virtq *vq = &vdev->vq[rx_queue];
-- 
2.54.0


  parent reply	other threads:[~2026-06-16 17:11 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-16 17:10 [PATCH 0/8] multithreading: Prepare data structures for concurrent queue pair workers Laurent Vivier
2026-06-16 17:10 ` [PATCH 1/8] tap: Convert packet pools to per-queue-pair arrays for multiqueue Laurent Vivier
2026-06-16 17:10 ` [PATCH 2/8] tap: Make L4 sequence pools per-qpair for thread safety Laurent Vivier
2026-06-16 17:10 ` [PATCH 3/8] tcp: Make static buffers stack-local " Laurent Vivier
2026-06-16 17:10 ` Laurent Vivier [this message]
2026-06-16 17:10 ` [PATCH 5/8] flow: Make flow timer per-caller " Laurent Vivier
2026-06-16 17:10 ` [PATCH 6/8] tcp: Make TCP timer state per-caller and guard global tasks Laurent Vivier
2026-06-16 17:10 ` [PATCH 7/8] tcp: Protect init socket pools with mutex for thread safety Laurent Vivier
2026-06-16 17:10 ` [PATCH 8/8] flow: Add mutex and per-qpair filtering to flow table operations Laurent Vivier

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