[PATCH net-next 2/5] RDS: limit the number of times we loop in rds_send_xmit

Gerd Rausch
2019-08-13T18:20:48Z

From: Chris Mason <chris.mason@oracle.com>
Date: Fri, 3 Feb 2012 11:07:54 -0500

This will kick the RDS worker thread if we have been looping
too long.

Original commit from 2012 updated to include a change by
Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com>
that triggers "must_wake" if "rds_ib_recv_refill_one" fails.

Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
---
net/rds/ib_recv.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 3cae88cbdaa0..1a8a4a760b84 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -385,6 +385,7 @@ void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp)
unsigned int posted = 0;
int ret = 0;
bool can_wait = !!(gfp & __GFP_DIRECT_RECLAIM);
+ bool must_wake = false;
u32 pos;

/* the goal here is to just make sure that someone, somewhere
@@ -405,6 +406,7 @@ void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp)
recv = &ic->i_recvs[pos];
ret = rds_ib_recv_refill_one(conn, recv, gfp);
if (ret) {
+ must_wake = true;
break;
}

@@ -423,6 +425,11 @@ void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp)
}

posted++;
+
+ if ((posted > 128 && need_resched()) || posted > 8192) {
+ must_wake = true;
+ break;
+ }
}

/* We're doing flow control - update the window. */
@@ -445,10 +452,13 @@ void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp)
* if we should requeue.
*/
if (rds_conn_up(conn) &&
- ((can_wait && rds_ib_ring_low(&ic->i_recv_ring)) ||
+ (must_wake ||
+ (can_wait && rds_ib_ring_low(&ic->i_recv_ring)) ||
rds_ib_ring_empty(&ic->i_recv_ring))) {
queue_delayed_work(rds_wq, &conn->c_recv_w, 1);
}
+ if (can_wait)
+ cond_resched();
}

/*
--
2.22.0