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Subject[PATCH 4.14 053/183] IB/cq: Dont force IB_POLL_DIRECT poll context for ib_process_cq_direct
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sagi Grimberg <sagi@grimberg.me>


[ Upstream commit 246d8b184c100e8eb6b4e8c88f232c2ed2a4e672 ]

polling the completion queue directly does not interfere
with the existing polling logic, hence drop the requirement.
Be aware that running ib_process_cq_direct with non IB_POLL_DIRECT
CQ may trigger concurrent CQ processing.

This can be used for polling mode ULPs.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Reported-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
[maxg: added wcs array argument to __ib_process_cq]
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/infiniband/core/cq.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

--- a/drivers/infiniband/core/cq.c
+++ b/drivers/infiniband/core/cq.c
@@ -25,9 +25,10 @@
#define IB_POLL_FLAGS \
(IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)

-static int __ib_process_cq(struct ib_cq *cq, int budget)
+static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc)
{
int i, n, completed = 0;
+ struct ib_wc *wcs = poll_wc ? : cq->wc;

/*
* budget might be (-1) if the caller does not
@@ -35,9 +36,9 @@ static int __ib_process_cq(struct ib_cq
* minimum here.
*/
while ((n = ib_poll_cq(cq, min_t(u32, IB_POLL_BATCH,
- budget - completed), cq->wc)) > 0) {
+ budget - completed), wcs)) > 0) {
for (i = 0; i < n; i++) {
- struct ib_wc *wc = &cq->wc[i];
+ struct ib_wc *wc = &wcs[i];

if (wc->wr_cqe)
wc->wr_cqe->done(cq, wc);
@@ -60,18 +61,20 @@ static int __ib_process_cq(struct ib_cq
* @cq: CQ to process
* @budget: number of CQEs to poll for
*
- * This function is used to process all outstanding CQ entries on a
- * %IB_POLL_DIRECT CQ. It does not offload CQ processing to a different
- * context and does not ask for completion interrupts from the HCA.
+ * This function is used to process all outstanding CQ entries.
+ * It does not offload CQ processing to a different context and does
+ * not ask for completion interrupts from the HCA.
+ * Using direct processing on CQ with non IB_POLL_DIRECT type may trigger
+ * concurrent processing.
*
* Note: do not pass -1 as %budget unless it is guaranteed that the number
* of completions that will be processed is small.
*/
int ib_process_cq_direct(struct ib_cq *cq, int budget)
{
- WARN_ON_ONCE(cq->poll_ctx != IB_POLL_DIRECT);
+ struct ib_wc wcs[IB_POLL_BATCH];

- return __ib_process_cq(cq, budget);
+ return __ib_process_cq(cq, budget, wcs);
}
EXPORT_SYMBOL(ib_process_cq_direct);

@@ -85,7 +88,7 @@ static int ib_poll_handler(struct irq_po
struct ib_cq *cq = container_of(iop, struct ib_cq, iop);
int completed;

- completed = __ib_process_cq(cq, budget);
+ completed = __ib_process_cq(cq, budget, NULL);
if (completed < budget) {
irq_poll_complete(&cq->iop);
if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
@@ -105,7 +108,7 @@ static void ib_cq_poll_work(struct work_
struct ib_cq *cq = container_of(work, struct ib_cq, work);
int completed;

- completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE);
+ completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, NULL);
if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
queue_work(ib_comp_wq, &cq->work);

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