From: Michael J. Ruhl michael.j.ruhl@intel.com

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@vger.kernel.org # 4.19.x Reviewed-by: Mitko Haralanov mitko.haralanov@intel.com Reviewed-by: Mike Marciniszyn mike.marciniszyn@intel.com Signed-off-by: Michael J. Ruhl michael.j.ruhl@intel.com Signed-off-by: Dennis Dalessandro dennis.dalessandro@intel.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com --- drivers/infiniband/hw/hfi1/user_sdma.c | 24 ++++++++++-------------- drivers/infiniband/hw/hfi1/user_sdma.h | 9 +++++---- 2 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/user_sdma.c b/drivers/infiniband/hw/hfi1/user_sdma.c index 39134dd..51831bf 100644 --- a/drivers/infiniband/hw/hfi1/user_sdma.c +++ b/drivers/infiniband/hw/hfi1/user_sdma.c @@ -187,7 +187,6 @@ int hfi1_user_sdma_alloc_queues(struct hfi1_ctxtdata *uctxt, pq->ctxt = uctxt->ctxt; pq->subctxt = fd->subctxt; pq->n_max_reqs = hfi1_sdma_comp_ring_size; - pq->state = SDMA_PKT_Q_INACTIVE; atomic_set(&pq->n_reqs, 0); init_waitqueue_head(&pq->wait); atomic_set(&pq->n_locked, 0); @@ -276,7 +275,7 @@ int hfi1_user_sdma_free_queues(struct hfi1_filedata *fd, /* Wait until all requests have been freed. */ wait_event_interruptible( pq->wait, - (READ_ONCE(pq->state) == SDMA_PKT_Q_INACTIVE)); + !atomic_read(&pq->n_reqs)); kfree(pq->reqs); kfree(pq->req_in_use); kmem_cache_destroy(pq->txreq_cache); @@ -312,6 +311,13 @@ static u8 dlid_to_selector(u16 dlid) return mapping[hash]; }

+/** + * hfi1_user_sdma_process_request() - Process and start a user sdma request + * @fd: valid file descriptor + * @iovec: array of io vectors to process + * @dim: overall iovec array size + * @count: number of io vector array entries processed + */ int hfi1_user_sdma_process_request(struct hfi1_filedata *fd, struct iovec *iovec, unsigned long dim, unsigned long *count) @@ -560,21 +566,13 @@ int hfi1_user_sdma_process_request(struct hfi1_filedata *fd, req->ahg_idx = sdma_ahg_alloc(req->sde);

set_comp_state(pq, cq, info.comp_idx, QUEUED, 0); + pq->state = SDMA_PKT_Q_ACTIVE; /* Send the first N packets in the request to buy us some time */ ret = user_sdma_send_pkts(req, pcount); if (unlikely(ret < 0 && ret != -EBUSY)) goto free_req;

/* - * It is possible that the SDMA engine would have processed all the - * submitted packets by the time we get here. Therefore, only set - * packet queue state to ACTIVE if there are still uncompleted - * requests. - */ - if (atomic_read(&pq->n_reqs)) - xchg(&pq->state, SDMA_PKT_Q_ACTIVE); - - /* * This is a somewhat blocking send implementation. * The driver will block the caller until all packets of the * request have been submitted to the SDMA engine. However, it @@ -1409,10 +1407,8 @@ static void user_sdma_txreq_cb(struct sdma_txreq *txreq, int status)

static inline void pq_update(struct hfi1_user_sdma_pkt_q *pq) { - if (atomic_dec_and_test(&pq->n_reqs)) { - xchg(&pq->state, SDMA_PKT_Q_INACTIVE); + if (atomic_dec_and_test(&pq->n_reqs)) wake_up(&pq->wait); - } }

static void user_sdma_free_request(struct user_sdma_request *req, bool unpin) diff --git a/drivers/infiniband/hw/hfi1/user_sdma.h b/drivers/infiniband/hw/hfi1/user_sdma.h index 0ae0645..91c343f 100644 --- a/drivers/infiniband/hw/hfi1/user_sdma.h +++ b/drivers/infiniband/hw/hfi1/user_sdma.h @@ -105,9 +105,10 @@ static inline int ahg_header_set(u32 *arr, int idx, size_t array_size, #define TXREQ_FLAGS_REQ_ACK BIT(0) /* Set the ACK bit in the header */ #define TXREQ_FLAGS_REQ_DISABLE_SH BIT(1) /* Disable header suppression */

-#define SDMA_PKT_Q_INACTIVE BIT(0) -#define SDMA_PKT_Q_ACTIVE BIT(1) -#define SDMA_PKT_Q_DEFERRED BIT(2) +enum pkt_q_sdma_state { + SDMA_PKT_Q_ACTIVE, + SDMA_PKT_Q_DEFERRED, +};

/* * Maximum retry attempts to submit a TX request @@ -133,7 +134,7 @@ struct hfi1_user_sdma_pkt_q { struct user_sdma_request *reqs; unsigned long *req_in_use; struct iowait busy; - unsigned state; + enum pkt_q_sdma_state state; wait_queue_head_t wait; unsigned long unpinned; struct mmu_rb_handler *handler;