[PATCH] RDMA/cxgb4: Don't exceed hw IQ depth limit for user CQs.

[PATCH] RDMA/cxgb4: Don't exceed hw IQ depth limit for user CQs.

[Steve Wise]

Memory allocated for user CQs gets rounded up to the next page boundary.
And after rounding, we recalculate the resulting IQ depth and we need
to make sure we don't exceed the HW limits.

This bug can result a much smaller CQ allocated than was expected if
the HW size field is exceeded, resulting in CQ overflow failures.

Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
---

 drivers/infiniband/hw/cxgb4/cq.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cq.c b/drivers/infiniband/hw/cxgb4/cq.c
index 8d8f8ad..1720dc7 100644
--- a/drivers/infiniband/hw/cxgb4/cq.c
+++ b/drivers/infiniband/hw/cxgb4/cq.c
@@ -801,6 +801,10 @@ struct ib_cq *c4iw_create_cq(struct ib_device *ibdev, int entries,
 	if (ucontext) {
 		memsize = roundup(memsize, PAGE_SIZE);
 		hwentries = memsize / sizeof *chp->cq.queue;
+		while (hwentries > T4_MAX_IQ_SIZE) {
+			memsize -= PAGE_SIZE;
+			hwentries = memsize / sizeof *chp->cq.queue;
+		}
 	}
 	chp->cq.size = hwentries;
 	chp->cq.memsize = memsize;

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