diff mbox series

[v2,net-next,14/14] net_sched: sch_skbprio: implement lockless skbprio_dump()

Message ID 20240418073248.2952954-15-edumazet@google.com (mailing list archive)
State Accepted
Commit c85cedb38f41bebc3da08c4a7bc58c5f62a2a950
Delegated to: Netdev Maintainers
Headers show
Series net_sched: first series for RTNL-less qdisc dumps | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 926 this patch: 926
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 937 this patch: 937
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 937 this patch: 937
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 26 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-04-19--00-00 (tests: 961)

Commit Message

Eric Dumazet April 18, 2024, 7:32 a.m. UTC 
Instead of relying on RTNL, skbprio_dump() can use READ_ONCE()
annotation, paired with WRITE_ONCE() one in skbprio_change().

Also add a READ_ONCE(sch->limit) in skbprio_enqueue().

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/sched/sch_skbprio.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Simon Horman April 18, 2024, 3:04 p.m. UTC | #1 
On Thu, Apr 18, 2024 at 07:32:48AM +0000, Eric Dumazet wrote:
> Instead of relying on RTNL, skbprio_dump() can use READ_ONCE()
> annotation, paired with WRITE_ONCE() one in skbprio_change().
> 
> Also add a READ_ONCE(sch->limit) in skbprio_enqueue().
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Simon Horman <horms@kernel.org>
diff mbox series

Patch

diff --git a/net/sched/sch_skbprio.c b/net/sched/sch_skbprio.c
index b4dd626c309c36725e6030a338d21d1fabcb6704..20ff7386b74bd89c00b50a8f0def91b6c5cce7f4 100644
--- a/net/sched/sch_skbprio.c
+++ b/net/sched/sch_skbprio.c
@@ -79,7 +79,9 @@  static int skbprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 	prio = min(skb->priority, max_priority);
 
 	qdisc = &q->qdiscs[prio];
-	if (sch->q.qlen < sch->limit) {
+
+	/* sch->limit can change under us from skbprio_change() */
+	if (sch->q.qlen < READ_ONCE(sch->limit)) {
 		__skb_queue_tail(qdisc, skb);
 		qdisc_qstats_backlog_inc(sch, skb);
 		q->qstats[prio].backlog += qdisc_pkt_len(skb);
@@ -172,7 +174,7 @@  static int skbprio_change(struct Qdisc *sch, struct nlattr *opt,
 	if (opt->nla_len != nla_attr_size(sizeof(*ctl)))
 		return -EINVAL;
 
-	sch->limit = ctl->limit;
+	WRITE_ONCE(sch->limit, ctl->limit);
 	return 0;
 }
 
@@ -200,7 +202,7 @@  static int skbprio_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
 	struct tc_skbprio_qopt opt;
 
-	opt.limit = sch->limit;
+	opt.limit = READ_ONCE(sch->limit);
 
 	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 		return -1;