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authorSagi Grimberg <sagig@mellanox.com>2014-10-01 14:02:08 +0300
committerRoland Dreier <roland@purestorage.com>2014-10-09 00:06:06 -0700
commit183cfa434ec90897b1423ce4f916e8a237139133 (patch)
tree9987bfe5479c8f6792adafbc0221e704dc657613 /drivers/infiniband
parentbf17554035ab2aaf770321208ce48e69aab71cc8 (diff)
IB/iser: Use internal polling budget to avoid possible live-lock
We need a way to guarentee that we don't stay in soft-IRQ context for too long. We might starve other pending CQ tasklets or worse lock against application trying to issue IO on the running CPU. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Roi Dayan <roid@mellanox.com> Signed-off-by: Ariel Nahum <arieln@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
Diffstat (limited to 'drivers/infiniband')
-rw-r--r--drivers/infiniband/ulp/iser/iser_verbs.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c
index 94d1b46b467a..e31ac57accc9 100644
--- a/drivers/infiniband/ulp/iser/iser_verbs.c
+++ b/drivers/infiniband/ulp/iser/iser_verbs.c
@@ -42,6 +42,8 @@
#define ISER_MAX_RX_CQ_LEN (ISER_QP_MAX_RECV_DTOS * ISCSI_ISER_MAX_CONN)
#define ISER_MAX_TX_CQ_LEN (ISER_QP_MAX_REQ_DTOS * ISCSI_ISER_MAX_CONN)
+static int iser_cq_poll_limit = 512;
+
static void iser_cq_tasklet_fn(unsigned long data);
static void iser_cq_callback(struct ib_cq *cq, void *cq_context);
static int iser_drain_tx_cq(struct iser_comp *comp);
@@ -1248,6 +1250,8 @@ static void iser_cq_tasklet_fn(unsigned long data)
completed_rx++;
if (!(completed_rx & 63))
completed_tx += iser_drain_tx_cq(comp);
+ if (completed_rx >= iser_cq_poll_limit)
+ break;
}
/* #warning "it is assumed here that arming CQ only once its empty" *
* " would not cause interrupts to be missed" */