dql: Fix dql->limit value when reset.

[ Upstream commit 3a17f23f7c36bac3a3584aaf97d3e3e0b2790396 ]

Executing dql_reset after setting a non-zero value for limit_min can
lead to an unreasonable situation where dql->limit is less than
dql->limit_min.

For instance, after setting
/sys/class/net/eth*/queues/tx-0/byte_queue_limits/limit_min,
an ifconfig down/up operation might cause the ethernet driver to call
netdev_tx_reset_queue, which in turn invokes dql_reset.

In this case, dql->limit is reset to 0 while dql->limit_min remains
non-zero value, which is unexpected. The limit should always be
greater than or equal to limit_min.

Signed-off-by: Jing Su <jingsusu@didiglobal.com>
Link: https://patch.msgid.link/Z9qHD1s/NEuQBdgH@pilot-ThinkCentre-M930t-N000
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/lib/dynamic_queue_limits.c b/lib/dynamic_queue_limits.c
index fde0aa2441480032d8ec1b2a42fef62753c0afe2..a75a9ca46b594050c915081e634b12885d68e53d 100644 (file)
--- a/lib/dynamic_queue_limits.c
+++ b/lib/dynamic_queue_limits.c
@@ -116,7 +116,7 @@ EXPORT_SYMBOL(dql_completed);
 void dql_reset(struct dql *dql)
 {
        /* Reset all dynamic values */
-       dql->limit = 0;
+       dql->limit = dql->min_limit;
        dql->num_queued = 0;
        dql->num_completed = 0;
        dql->last_obj_cnt = 0;