From 43509d1fece975ac457282ca1137fe438894a81d Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Wed, 18 Jul 2007 13:28:29 -0700 Subject: IB/mthca: Simplify use of size0 in work request posting Current code sets size0 to 0 at the start of work request posting functions and then handles size0 == 0 specially within the loop over work requests. Change this so size0 is set along with f0 the first time through the loop (when nreq == 0). This makes the code easier to understand by making it clearer that f0 and size0 are always initialized if nreq != 0 without having to know that size0 == 0 implies nreq == 0. Also annotate size0 with uninitialized_var() so that this doesn't introduce a new compiler warning. Signed-off-by: Roland Dreier --- drivers/infiniband/hw/mthca/mthca_qp.c | 41 ++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 17 deletions(-) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c index b5bd704ca55d..df01b2026a64 100644 --- a/drivers/infiniband/hw/mthca/mthca_qp.c +++ b/drivers/infiniband/hw/mthca/mthca_qp.c @@ -1629,13 +1629,14 @@ int mthca_tavor_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, int nreq; int i; int size; - int size0 = 0; /* - * f0 is only used if nreq != 0, and f0 will be initialized - * the first time through the main loop, since size0 == 0 the - * first time through. So nreq cannot become non-zero without - * initializing f0, and f0 is in fact never used uninitialized. + * f0 and size0 are only used if nreq != 0, and they will + * always be initialized the first time through the main loop + * before nreq is incremented. So nreq cannot become non-zero + * without initializing f0 and size0, and they are in fact + * never used uninitialized. */ + int uninitialized_var(size0); u32 uninitialized_var(f0); int ind; u8 op0 = 0; @@ -1780,11 +1781,11 @@ int mthca_tavor_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, mthca_opcode[wr->opcode]); wmb(); ((struct mthca_next_seg *) prev_wqe)->ee_nds = - cpu_to_be32((size0 ? 0 : MTHCA_NEXT_DBD) | size | + cpu_to_be32((nreq ? 0 : MTHCA_NEXT_DBD) | size | ((wr->send_flags & IB_SEND_FENCE) ? MTHCA_NEXT_FENCE : 0)); - if (!size0) { + if (!nreq) { size0 = size; op0 = mthca_opcode[wr->opcode]; f0 = wr->send_flags & IB_SEND_FENCE ? @@ -1834,7 +1835,14 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr, int nreq; int i; int size; - int size0 = 0; + /* + * size0 is only used if nreq != 0, and it will always be + * initialized the first time through the main loop before + * nreq is incremented. So nreq cannot become non-zero + * without initializing size0, and it is in fact never used + * uninitialized. + */ + int uninitialized_var(size0); int ind; void *wqe; void *prev_wqe; @@ -1888,7 +1896,7 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr, ((struct mthca_next_seg *) prev_wqe)->ee_nds = cpu_to_be32(MTHCA_NEXT_DBD | size); - if (!size0) + if (!nreq) size0 = size; ++ind; @@ -1910,7 +1918,6 @@ int mthca_tavor_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr, qp->rq.next_ind = ind; qp->rq.head += MTHCA_TAVOR_MAX_WQES_PER_RECV_DB; - size0 = 0; } } @@ -1952,13 +1959,14 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, int nreq; int i; int size; - int size0 = 0; /* - * f0 is only used if nreq != 0, and f0 will be initialized - * the first time through the main loop, since size0 == 0 the - * first time through. So nreq cannot become non-zero without - * initializing f0, and f0 is in fact never used uninitialized. + * f0 and size0 are only used if nreq != 0, and they will + * always be initialized the first time through the main loop + * before nreq is incremented. So nreq cannot become non-zero + * without initializing f0 and size0, and they are in fact + * never used uninitialized. */ + int uninitialized_var(size0); u32 uninitialized_var(f0); int ind; u8 op0 = 0; @@ -1979,7 +1987,6 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, doorbell[1] = cpu_to_be32((qp->qpn << 8) | size0); qp->sq.head += MTHCA_ARBEL_MAX_WQES_PER_SEND_DB; - size0 = 0; /* * Make sure that descriptors are written before @@ -2133,7 +2140,7 @@ int mthca_arbel_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr, ((wr->send_flags & IB_SEND_FENCE) ? MTHCA_NEXT_FENCE : 0)); - if (!size0) { + if (!nreq) { size0 = size; op0 = mthca_opcode[wr->opcode]; f0 = wr->send_flags & IB_SEND_FENCE ? -- cgit v1.2.3