From d395117fac7943da6966ccbac3b95651f5581f15 Mon Sep 17 00:00:00 2001 From: "Michael J. Ruhl" Date: Tue, 18 Dec 2018 16:08:32 -0500 Subject: IB/hfi1: Remove race conditions in user_sdma send path 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: # 4.9.0 Reviewed-by: Mitko Haralanov Reviewed-by: Mike Marciniszyn Signed-off-by: Michael J. Ruhl Signed-off-by: Sasha Levin --- drivers/infiniband/hw/hfi1/user_sdma.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'drivers/infiniband/hw/hfi1/user_sdma.h') diff --git a/drivers/infiniband/hw/hfi1/user_sdma.h b/drivers/infiniband/hw/hfi1/user_sdma.h index 39001714f551..09dd843a13de 100644 --- a/drivers/infiniband/hw/hfi1/user_sdma.h +++ b/drivers/infiniband/hw/hfi1/user_sdma.h @@ -53,6 +53,11 @@ extern uint extended_psn; +enum pkt_q_sdma_state { + SDMA_PKT_Q_ACTIVE, + SDMA_PKT_Q_DEFERRED, +}; + struct hfi1_user_sdma_pkt_q { struct list_head list; unsigned ctxt; @@ -65,7 +70,7 @@ 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; -- cgit v1.2.3