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IB/mthca: Simplify use of size0 in work request posting

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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 <rolandd@cisco.com>
This commit is contained in:
Roland Dreier 2007-07-18 13:28:29 -07:00
parent e535c699bf
commit 43509d1fec
1 changed files with 24 additions and 17 deletions
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41
drivers/infiniband/hw/mthca/mthca_qp.c
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@ -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 ?