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contrib/libvhost-user: Protect slave fd with mutex

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In future patches we'll be performing commands on the slave-fd driven
by commands on queues, since those queues will be driven by individual
threads we need to make sure they don't attempt to use the slave-fd
for multiple commands in parallel.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2019-03-01 11:18:30 +00:00
parent 0fdc465d7d
commit c25c02b9e6
2 changed files with 23 additions and 4 deletions
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24
contrib/libvhost-user/libvhost-user.c
View File

@ -392,26 +392,37 @@ vu_send_reply(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
return vu_message_write(dev, conn_fd, vmsg); return vu_message_write(dev, conn_fd, vmsg);
} }
/*
* Processes a reply on the slave channel.
* Entered with slave_mutex held and releases it before exit.
* Returns true on success.
*/
static bool static bool
vu_process_message_reply(VuDev *dev, const VhostUserMsg *vmsg) vu_process_message_reply(VuDev *dev, const VhostUserMsg *vmsg)
{ {
VhostUserMsg msg_reply; VhostUserMsg msg_reply;
bool result = false;
if ((vmsg->flags & VHOST_USER_NEED_REPLY_MASK) == 0) { if ((vmsg->flags & VHOST_USER_NEED_REPLY_MASK) == 0) {
return true; result = true;
goto out;
} }
if (!vu_message_read(dev, dev->slave_fd, &msg_reply)) { if (!vu_message_read(dev, dev->slave_fd, &msg_reply)) {
return false; goto out;
} }
if (msg_reply.request != vmsg->request) { if (msg_reply.request != vmsg->request) {
DPRINT("Received unexpected msg type. Expected %d received %d", DPRINT("Received unexpected msg type. Expected %d received %d",
vmsg->request, msg_reply.request); vmsg->request, msg_reply.request);
return false; goto out;
} }
return msg_reply.payload.u64 == 0; result = msg_reply.payload.u64 == 0;
out:
pthread_mutex_unlock(&dev->slave_mutex);
return result;
} }
/* Kick the log_call_fd if required. */ /* Kick the log_call_fd if required. */
@ -1105,10 +1116,13 @@ bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd,
return false; return false;
} }
pthread_mutex_lock(&dev->slave_mutex);
if (!vu_message_write(dev, dev->slave_fd, &vmsg)) { if (!vu_message_write(dev, dev->slave_fd, &vmsg)) {
pthread_mutex_unlock(&dev->slave_mutex);
return false; return false;
} }
/* Also unlocks the slave_mutex */
return vu_process_message_reply(dev, &vmsg); return vu_process_message_reply(dev, &vmsg);
} }
@ -1628,6 +1642,7 @@ vu_deinit(VuDev *dev)
close(dev->slave_fd); close(dev->slave_fd);
dev->slave_fd = -1; dev->slave_fd = -1;
} }
pthread_mutex_destroy(&dev->slave_mutex);
if (dev->sock != -1) { if (dev->sock != -1) {
close(dev->sock); close(dev->sock);
@ -1663,6 +1678,7 @@ vu_init(VuDev *dev,
dev->remove_watch = remove_watch; dev->remove_watch = remove_watch;
dev->iface = iface; dev->iface = iface;
dev->log_call_fd = -1; dev->log_call_fd = -1;
pthread_mutex_init(&dev->slave_mutex, NULL);
dev->slave_fd = -1; dev->slave_fd = -1;
dev->max_queues = max_queues; dev->max_queues = max_queues;

3
contrib/libvhost-user/libvhost-user.h
View File

@ -19,6 +19,7 @@
#include <stddef.h> #include <stddef.h>
#include <sys/poll.h> #include <sys/poll.h>
#include <linux/vhost.h> #include <linux/vhost.h>
#include <pthread.h>
#include "standard-headers/linux/virtio_ring.h" #include "standard-headers/linux/virtio_ring.h"
/* Based on qemu/hw/virtio/vhost-user.c */ /* Based on qemu/hw/virtio/vhost-user.c */
@ -355,6 +356,8 @@ struct VuDev {
VuVirtq *vq; VuVirtq *vq;
VuDevInflightInfo inflight_info; VuDevInflightInfo inflight_info;
int log_call_fd; int log_call_fd;
/* Must be held while using slave_fd */
pthread_mutex_t slave_mutex;
int slave_fd; int slave_fd;
uint64_t log_size; uint64_t log_size;
uint8_t *log_table; uint8_t *log_table;