Hello Samar, On Fri, Jul 3, 2026 at 12:25 PM Samar Yadav <[email protected]> wrote: > > virtio_user secondary processes cannot communicate with the vhost > backend: the kick/call eventfds are opened by the primary and never > shared, so a secondary's queue notification writes to an invalid fd > and traffic stalls. > > Share the fds over a dedicated virtio-user multiprocess channel. The > primary registers a process-wide MP action that returns a port's > kick/call fds (looked up by port name); a secondary requests them at > probe time, before the port is announced. > > The received fds are stored in eth_dev->process_private, which is > per-process, instead of the primary-owned shared dev->kickfds and > dev->callfds arrays; the secondary data path notifies the backend using > its own kickfd. In the primary, the MP handler reads the fd arrays under > dev->mutex, and the teardown path takes the same lock while closing and > freeing them, so the two cannot race. > > Also fix the pre-existing pthread_mutex_init(&dev->mutex, NULL) call in > virtio_user_dev_init(): POSIX requires PTHREAD_PROCESS_SHARED for a mutex > stored in shared memory regardless of which processes actually lock it; > use rte_thread_mutex_init_shared() as other multiprocess-aware drivers do. > > Fixes: 1c8489da561b ("net/virtio-user: fix multi-process support") > Cc: [email protected] > Cc: [email protected] > > Signed-off-by: Samar Yadav <[email protected]> > --- > v3: > - Reorder new #includes: system headers first, then DPDK lib headers > (alphabetized), then local virtio_* headers, per project convention. > - Name the "2" in eventfd count/index arithmetic (kick + call per queue) > as VIRTIO_USER_EVENTFDS_PER_QUEUE instead of a bare literal. Leaves > the pre-existing max_queue_pairs * 2 vring math untouched, since that > is a different multiplier (vrings per queue pair) and already matches > this file's existing style. > - Name the 5-second MP reply timeout in virtio_user_sync_eventfds() as > VIRTIO_USER_MP_TIMEOUT_SEC with a comment on the rationale. > > v2: > - Use rte_calloc() instead of rte_malloc() for the kick/call fd arrays > in virtio_user_sync_eventfds() so allocation failures are cleaner and > unset entries are zero-initialised before the explicit -1 sentinel loop. > (Stephen Hemminger) > - Fix the pre-existing pthread_mutex_init(&dev->mutex, NULL) call in > virtio_user_dev_init() to use rte_thread_mutex_init_shared(), which > sets PTHREAD_PROCESS_SHARED as POSIX requires for a mutex in shared > memory. Add #include <rte_thread.h> to pull in the declaration. > (Stephen Hemminger) > > .mailmap | 1 + > .../net/virtio/virtio_user/virtio_user_dev.c | 59 +++- > .../net/virtio/virtio_user/virtio_user_dev.h | 23 ++ > drivers/net/virtio/virtio_user_ethdev.c | 276 +++++++++++++++++- > 4 files changed, 350 insertions(+), 9 deletions(-) >
The patch looks good to me. Reviewed-by: Maxime Coquelin <[email protected]> Thanks, Maxime
