diff mbox series

[v2,net-next,04/14] net_sched: sch_choke: implement lockless choke_dump()

Message ID 20240418073248.2952954-5-edumazet@google.com (mailing list archive)
State Accepted
Commit 7253c1d1e7a52504ffd08138e9843d0a80788690
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 Errors and warnings before: 0 this patch: 0
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, 71 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, choke_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in choke_change().

v2: added a WRITE_ONCE(p->Scell_log, Scell_log)
    per Simon feedback in V1
    Removed the READ_ONCE(q->limit) in choke_enqueue()

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/red.h     | 12 ++++++------
 net/sched/sch_choke.c | 21 +++++++++++----------
 2 files changed, 17 insertions(+), 16 deletions(-)

Comments

Simon Horman April 18, 2024, 1:58 p.m. UTC | #1 
On Thu, Apr 18, 2024 at 07:32:38AM +0000, Eric Dumazet wrote:
> Instead of relying on RTNL, choke_dump() can use READ_ONCE()
> annotations, paired with WRITE_ONCE() ones in choke_change().
> 
> v2: added a WRITE_ONCE(p->Scell_log, Scell_log)
>     per Simon feedback in V1
>     Removed the READ_ONCE(q->limit) in choke_enqueue()
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

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

Patch

diff --git a/include/net/red.h b/include/net/red.h
index 425364de0df7913cdd6361a0eb8d18b418372787..802287d52c9e37e76ba9154539f511629e4b9780 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -233,10 +233,10 @@  static inline void red_set_parms(struct red_parms *p,
 	int delta = qth_max - qth_min;
 	u32 max_p_delta;
 
-	p->qth_min	= qth_min << Wlog;
-	p->qth_max	= qth_max << Wlog;
-	p->Wlog		= Wlog;
-	p->Plog		= Plog;
+	WRITE_ONCE(p->qth_min, qth_min << Wlog);
+	WRITE_ONCE(p->qth_max, qth_max << Wlog);
+	WRITE_ONCE(p->Wlog, Wlog);
+	WRITE_ONCE(p->Plog, Plog);
 	if (delta <= 0)
 		delta = 1;
 	p->qth_delta	= delta;
@@ -244,7 +244,7 @@  static inline void red_set_parms(struct red_parms *p,
 		max_P = red_maxp(Plog);
 		max_P *= delta; /* max_P = (qth_max - qth_min)/2^Plog */
 	}
-	p->max_P = max_P;
+	WRITE_ONCE(p->max_P, max_P);
 	max_p_delta = max_P / delta;
 	max_p_delta = max(max_p_delta, 1U);
 	p->max_P_reciprocal  = reciprocal_value(max_p_delta);
@@ -257,7 +257,7 @@  static inline void red_set_parms(struct red_parms *p,
 	p->target_min = qth_min + 2*delta;
 	p->target_max = qth_min + 3*delta;
 
-	p->Scell_log	= Scell_log;
+	WRITE_ONCE(p->Scell_log, Scell_log);
 	p->Scell_max	= (255 << Scell_log);
 
 	if (stab)
diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index ea108030c6b410418f0b58ba7ea51e1b524d4df9..91072010923d1825e811adbb8ea2b3035dda57b3 100644
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -405,8 +405,8 @@  static int choke_change(struct Qdisc *sch, struct nlattr *opt,
 	} else
 		sch_tree_lock(sch);
 
-	q->flags = ctl->flags;
-	q->limit = ctl->limit;
+	WRITE_ONCE(q->flags, ctl->flags);
+	WRITE_ONCE(q->limit, ctl->limit);
 
 	red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
 		      ctl->Plog, ctl->Scell_log,
@@ -431,15 +431,16 @@  static int choke_init(struct Qdisc *sch, struct nlattr *opt,
 static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
 	struct choke_sched_data *q = qdisc_priv(sch);
+	u8 Wlog = READ_ONCE(q->parms.Wlog);
 	struct nlattr *opts = NULL;
 	struct tc_red_qopt opt = {
-		.limit		= q->limit,
-		.flags		= q->flags,
-		.qth_min	= q->parms.qth_min >> q->parms.Wlog,
-		.qth_max	= q->parms.qth_max >> q->parms.Wlog,
-		.Wlog		= q->parms.Wlog,
-		.Plog		= q->parms.Plog,
-		.Scell_log	= q->parms.Scell_log,
+		.limit		= READ_ONCE(q->limit),
+		.flags		= READ_ONCE(q->flags),
+		.qth_min	= READ_ONCE(q->parms.qth_min) >> Wlog,
+		.qth_max	= READ_ONCE(q->parms.qth_max) >> Wlog,
+		.Wlog		= Wlog,
+		.Plog		= READ_ONCE(q->parms.Plog),
+		.Scell_log	= READ_ONCE(q->parms.Scell_log),
 	};
 
 	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
@@ -447,7 +448,7 @@  static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
 		goto nla_put_failure;
 
 	if (nla_put(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt) ||
-	    nla_put_u32(skb, TCA_CHOKE_MAX_P, q->parms.max_P))
+	    nla_put_u32(skb, TCA_CHOKE_MAX_P, READ_ONCE(q->parms.max_P)))
 		goto nla_put_failure;
 	return nla_nest_end(skb, opts);