On Tue, Dec 18, 2018 at 04:00:22PM -0500, Michael J. Ruhl wrote:
From: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx> commit 28a9a9e83ceae2cee25b9af9ad20d53aaa9ab951 upstream Packet queue state is over used to determine SDMA descriptor availablitity and packet queue request state. cpu 0 ret = user_sdma_send_pkts(req, pcount); cpu 0 if (atomic_read(&pq->n_reqs)) cpu 1 IRQ user_sdma_txreq_cb calls pq_update() (state to _INACTIVE) cpu 0 xchg(&pq->state, SDMA_PKT_Q_ACTIVE); At this point pq->n_reqs == 0 and pq->state is incorrectly SDMA_PKT_Q_ACTIVE. The close path will hang waiting for the state to return to _INACTIVE. This can also change the state from _DEFERRED to _ACTIVE. However, this is a mostly benign race. Remove the racy code path. Use n_reqs to determine if a packet queue is active or not. Cc: <stable@xxxxxxxxxxxxxxx> # 4.19.x Reviewed-by: Mitko Haralanov <mitko.haralanov@xxxxxxxxx> Reviewed-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx> Signed-off-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
I've queued all 3 to their respective trees, thank you. -- Thanks, Sasha
