RDMA/core: Reduce poll batch for direct cq polling

BugLink: http://bugs.launchpad.net/bugs/1774063
[ Upstream commit d3b9e8ad425cfd5b9116732e057f1b48e4d3bcb8 ]

Fix warning limit for kernel stack consumption:

drivers/infiniband/core/cq.c: In function 'ib_process_cq_direct':
drivers/infiniband/core/cq.c:78:1: error: the frame size of 1032 bytes
is larger than 1024 bytes [-Werror=frame-larger-than=]

Using smaller ib_wc array on the stack brings us comfortably below that
limit again.

Fixes: 246d8b184c10 ("IB/cq: Don't force IB_POLL_DIRECT poll context for ib_process_cq_direct")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sergey Gorenko <sergeygo@mellanox.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c
index c8c5a5a7f4336ce51185854044fe3196bd0c8589..757d308bebe84c2a9b093c44dc46654f50304022 100644 (file)
--- a/drivers/infiniband/core/cq.c
+++ b/drivers/infiniband/core/cq.c
@@ -17,6 +17,7 @@
 
 /* # of WCs to poll for with a single call to ib_poll_cq */
 #define IB_POLL_BATCH                  16
+#define IB_POLL_BATCH_DIRECT           8
 
 /* # of WCs to iterate over before yielding */
 #define IB_POLL_BUDGET_IRQ             256
@@ -25,18 +26,18 @@
 #define IB_POLL_FLAGS \
        (IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
 
-static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc)
+static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *wcs,
+                          int batch)
 {
        int i, n, completed = 0;
-       struct ib_wc *wcs = poll_wc ? : cq->wc;
 
        /*
         * budget might be (-1) if the caller does not
         * want to bound this call, thus we need unsigned
         * minimum here.
         */
-       while ((n = ib_poll_cq(cq, min_t(u32, IB_POLL_BATCH,
-                       budget - completed), wcs)) > 0) {
+       while ((n = ib_poll_cq(cq, min_t(u32, batch,
+                                        budget - completed), wcs)) > 0) {
                for (i = 0; i < n; i++) {
                        struct ib_wc *wc = &wcs[i];
 
@@ -48,8 +49,7 @@ static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc)
 
                completed += n;
 
-               if (n != IB_POLL_BATCH ||
-                   (budget != -1 && completed >= budget))
+               if (n != batch || (budget != -1 && completed >= budget))
                        break;
        }
 
@@ -72,9 +72,9 @@ static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *poll_wc)
  */
 int ib_process_cq_direct(struct ib_cq *cq, int budget)
 {
-       struct ib_wc wcs[IB_POLL_BATCH];
+       struct ib_wc wcs[IB_POLL_BATCH_DIRECT];
 
-       return __ib_process_cq(cq, budget, wcs);
+       return __ib_process_cq(cq, budget, wcs, IB_POLL_BATCH_DIRECT);
 }
 EXPORT_SYMBOL(ib_process_cq_direct);
 
@@ -88,7 +88,7 @@ static int ib_poll_handler(struct irq_poll *iop, int budget)
        struct ib_cq *cq = container_of(iop, struct ib_cq, iop);
        int completed;
 
-       completed = __ib_process_cq(cq, budget, NULL);
+       completed = __ib_process_cq(cq, budget, cq->wc, IB_POLL_BATCH);
        if (completed < budget) {
                irq_poll_complete(&cq->iop);
                if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
@@ -108,7 +108,8 @@ static void ib_cq_poll_work(struct 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, NULL);
+       completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, cq->wc,
+                                   IB_POLL_BATCH);
        if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
            ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
                queue_work(ib_comp_wq, &cq->work);