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 <rolandd@cisco.com>
diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c
index b5bd704..df01b20 100644
--- a/drivers/infiniband/hw/mthca/mthca_qp.c
+++ b/drivers/infiniband/hw/mthca/mthca_qp.c
@@ -1629,13 +1629,14 @@
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 @@
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 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 @@
((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 @@
qp->rq.next_ind = ind;
qp->rq.head += MTHCA_TAVOR_MAX_WQES_PER_RECV_DB;
- size0 = 0;
}
}
@@ -1952,13 +1959,14 @@
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 @@
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 @@
((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 ?