From 9944bddf80d692ade5ef6f7326541b13881cbbb9 Mon Sep 17 00:00:00 2001 From: Fei Chen Date: Mon, 1 Feb 2021 16:48:44 +0800 Subject: [PATCH] vhost: fix vid allocation race vhost_new_device might be called in different threads at the same time. thread 1(config thread) rte_vhost_driver_start ->vhost_user_start_client ->vhost_user_add_connection -> vhost_new_device thread 2(vhost-events) vhost_user_read_cb ->vhost_user_msg_handler (return value < 0) -> vhost_user_start_client -> vhost_new_device So there could be a case that a same vid has been allocated twice, or some vid might be lost in DPDK lib however still held by the upper applications. Another place where race would happen is at the func *vhost_destroy_device*, but after a detailed investigation, the race does not exist as long as no two devices have the same vid: Calling vhost_destroy_devices in different threads with different vids is actually safe. Fixes: a277c7159876 ("vhost: refactor code structure") Cc: stable@dpdk.org Reported-by: Peng He Signed-off-by: Fei Chen Reviewed-by: Zhihong Wang Reviewed-by: Chenbo Xia --- lib/librte_vhost/vhost.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c index efb136edd1..52ab93d1ec 100644 --- a/lib/librte_vhost/vhost.c +++ b/lib/librte_vhost/vhost.c @@ -26,6 +26,7 @@ #include "vhost_user.h" struct virtio_net *vhost_devices[MAX_VHOST_DEVICE]; +pthread_mutex_t vhost_dev_lock = PTHREAD_MUTEX_INITIALIZER; /* Called with iotlb_lock read-locked */ uint64_t @@ -645,6 +646,7 @@ vhost_new_device(void) struct virtio_net *dev; int i; + pthread_mutex_lock(&vhost_dev_lock); for (i = 0; i < MAX_VHOST_DEVICE; i++) { if (vhost_devices[i] == NULL) break; @@ -653,6 +655,7 @@ vhost_new_device(void) if (i == MAX_VHOST_DEVICE) { VHOST_LOG_CONFIG(ERR, "Failed to find a free slot for new device.\n"); + pthread_mutex_unlock(&vhost_dev_lock); return -1; } @@ -660,10 +663,13 @@ vhost_new_device(void) if (dev == NULL) { VHOST_LOG_CONFIG(ERR, "Failed to allocate memory for new dev.\n"); + pthread_mutex_unlock(&vhost_dev_lock); return -1; } vhost_devices[i] = dev; + pthread_mutex_unlock(&vhost_dev_lock); + dev->vid = i; dev->flags = VIRTIO_DEV_BUILTIN_VIRTIO_NET; dev->slave_req_fd = -1; -- 2.20.1