linux-kernel - [PATCH] RDMA/core: reduce IB_POLL

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Message-Id: <20180220205924.2035765-1-arnd@arndb.de>
Date:   Tue, 20 Feb 2018 21:59:09 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Doug Ledford <dledford@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Leon Romanovsky <leonro@...lanox.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] RDMA/core: reduce IB_POLL_BATCH constant

The ib_wc structure has grown to much that putting 16 of them on the stack
hits the warning limit for dangerous 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 half that number brings us comfortably below that limit again.

Fixes: 02d8883f520e ("RDMA/restrack: Add general infrastructure to track RDMA resources")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/infiniband/core/cq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c
index bc79ca8215d7..2626adbb978e 100644
--- a/drivers/infiniband/core/cq.c
+++ b/drivers/infiniband/core/cq.c
@@ -16,7 +16,7 @@
 #include <rdma/ib_verbs.h>
 
 /* # of WCs to poll for with a single call to ib_poll_cq */
-#define IB_POLL_BATCH			16
+#define IB_POLL_BATCH			8
 
 /* # of WCs to iterate over before yielding */
 #define IB_POLL_BUDGET_IRQ		256
-- 
2.9.0