remoteproc: implement synchronize_cbs() for virtio devices

Platform drivers invoke rproc_vq_interrupt() from hard-IRQ handlers,
threaded handlers, and work items. Because rpmsg callbacks may sleep,
the virtio core's synchronize_rcu() fallback does not synchronize with
callbacks across all these contexts. A device reset can therefore
complete while a callback is still running.

Add an SRCU domain per rproc. Protect both the queue lookup and
vring_interrupt() with it, and synchronize the domain in the new hook.

__rproc_virtio_del_vqs() can race with rproc_vq_interrupt() too. Clear
all queue pointers and synchronize the SRCU domain before freeing the
queues, so callers that already found a queue can finish using it.
Read rvring->vq once to avoid a second load after deletion starts.

The SRCU domain has the same lifetime as struct rproc. Its cleanup can
sleep, so document that rproc_free() and rproc_put() must not drop the
last reference from atomic context.

Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260908053817.26065-4-kmehltretter@gmail.com>

0 files changed, 0 insertions, 0 deletions