diff mbox series

[v2,net-next,08/14] net_sched: sch_fifo: implement lockless __fifo_dump()

Message ID 20240418073248.2952954-9-edumazet@google.com (mailing list archive)
State Accepted
Commit 01daf66b791e1ddd1a4aae2a65ea65fa1d4a96ef
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: 928 this patch: 928
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: 938 this patch: 938
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: 939 this patch: 939
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 49 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, __fifo_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in __fifo_init().

Also add missing READ_ONCE(sh->limit) in bfifo_enqueue(),
pfifo_enqueue() and pfifo_tail_enqueue().

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/sched/sch_fifo.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

Comments

Simon Horman April 18, 2024, 3:04 p.m. UTC | #1 
On Thu, Apr 18, 2024 at 07:32:42AM +0000, Eric Dumazet wrote:
> Instead of relying on RTNL, __fifo_dump() can use READ_ONCE()
> annotations, paired with WRITE_ONCE() ones in __fifo_init().
> 
> Also add missing READ_ONCE(sh->limit) in bfifo_enqueue(),
> pfifo_enqueue() and pfifo_tail_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_fifo.c b/net/sched/sch_fifo.c
index 450f5c67ac4956e21b544dfd81f886714171eced..b50b2c2cc09bc6ee5b23d9d5d3abea4423ff75b9 100644
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -19,7 +19,8 @@ 
 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 			 struct sk_buff **to_free)
 {
-	if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
+	if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <=
+		   READ_ONCE(sch->limit)))
 		return qdisc_enqueue_tail(skb, sch);
 
 	return qdisc_drop(skb, sch, to_free);
@@ -28,7 +29,7 @@  static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 			 struct sk_buff **to_free)
 {
-	if (likely(sch->q.qlen < sch->limit))
+	if (likely(sch->q.qlen < READ_ONCE(sch->limit)))
 		return qdisc_enqueue_tail(skb, sch);
 
 	return qdisc_drop(skb, sch, to_free);
@@ -39,7 +40,7 @@  static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 {
 	unsigned int prev_backlog;
 
-	if (likely(sch->q.qlen < sch->limit))
+	if (likely(sch->q.qlen < READ_ONCE(sch->limit)))
 		return qdisc_enqueue_tail(skb, sch);
 
 	prev_backlog = sch->qstats.backlog;
@@ -105,14 +106,14 @@  static int __fifo_init(struct Qdisc *sch, struct nlattr *opt,
 		if (is_bfifo)
 			limit *= psched_mtu(qdisc_dev(sch));
 
-		sch->limit = limit;
+		WRITE_ONCE(sch->limit, limit);
 	} else {
 		struct tc_fifo_qopt *ctl = nla_data(opt);
 
 		if (nla_len(opt) < sizeof(*ctl))
 			return -EINVAL;
 
-		sch->limit = ctl->limit;
+		WRITE_ONCE(sch->limit, ctl->limit);
 	}
 
 	if (is_bfifo)
@@ -154,7 +155,7 @@  static void fifo_destroy(struct Qdisc *sch)
 
 static int __fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
-	struct tc_fifo_qopt opt = { .limit = sch->limit };
+	struct tc_fifo_qopt opt = { .limit = READ_ONCE(sch->limit) };
 
 	if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
 		goto nla_put_failure;