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[net-next,v4,1/5] net: sched: Add multi-queue support to sch_tree_lock

Message ID 20210119120815.463334-2-maximmi@mellanox.com (mailing list archive)
State Accepted
Commit ca1e4ab199933e1af3f9a86d31060b7f9181c3fc
Delegated to: Netdev Maintainers
Headers show
Series HTB offload | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers success CCed 3 of 3 maintainers
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 4662 this patch: 4662
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 24 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 5085 this patch: 5085
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Maxim Mikityanskiy Jan. 19, 2021, 12:08 p.m. UTC 
The existing qdiscs that set TCQ_F_MQROOT don't use sch_tree_lock.
However, hardware-offloaded HTB will start setting this flag while also
using sch_tree_lock.

The current implementation of sch_tree_lock basically locks on
qdisc->dev_queue->qdisc, and it works fine when the tree is attached to
some queue. However, it's not the case for MQROOT qdiscs: such a qdisc
is the root itself, and its dev_queue just points to queue 0, while not
actually being used, because there are real per-queue qdiscs.

This patch changes the logic of sch_tree_lock and sch_tree_unlock to
lock the qdisc itself if it's the MQROOT.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
---
 include/net/sch_generic.h | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 639e465a108f..9448e8cf1ee6 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -551,14 +551,20 @@  static inline struct net_device *qdisc_dev(const struct Qdisc *qdisc)
 	return qdisc->dev_queue->dev;
 }
 
-static inline void sch_tree_lock(const struct Qdisc *q)
+static inline void sch_tree_lock(struct Qdisc *q)
 {
-	spin_lock_bh(qdisc_root_sleeping_lock(q));
+	if (q->flags & TCQ_F_MQROOT)
+		spin_lock_bh(qdisc_lock(q));
+	else
+		spin_lock_bh(qdisc_root_sleeping_lock(q));
 }
 
-static inline void sch_tree_unlock(const struct Qdisc *q)
+static inline void sch_tree_unlock(struct Qdisc *q)
 {
-	spin_unlock_bh(qdisc_root_sleeping_lock(q));
+	if (q->flags & TCQ_F_MQROOT)
+		spin_unlock_bh(qdisc_lock(q));
+	else
+		spin_unlock_bh(qdisc_root_sleeping_lock(q));
 }
 
 extern struct Qdisc noop_qdisc;