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Commit 43509d1f authored by Roland Dreier's avatar Roland Dreier
Browse files

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: default avatarRoland Dreier <rolandd@cisco.com>
parent e535c699

drivers/infiniband/hw/mthca/mthca_qp.c

+24 −17
Original line number Diff line number Diff line
@@ -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 ?