Commit a911bad0 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

dql: annotate data-races around dql->last_obj_cnt 



dql->last_obj_cnt is read/written from different contexts,
without any lock synchronization.

Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJoe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20241029191425.2519085-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 4138e9ec

include/linux/dynamic_queue_limits.h

+1 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ static inline void dql_queued(struct dql *dql, unsigned int count) 
	if (WARN_ON_ONCE(count > DQL_MAX_OBJECT))

		return;



	dql->last_obj_cnt = count;

	WRITE_ONCE(dql->last_obj_cnt, count);



	/* We want to force a write first, so that cpu do not attempt

	 * to get cache line containing last_obj_cnt, num_queued, adj_limit

lib/dynamic_queue_limits.c

+1 −1
Original line number Diff line number Diff line
@@ -179,7 +179,7 @@ void dql_completed(struct dql *dql, unsigned int count) 


	dql->adj_limit = limit + completed;

	dql->prev_ovlimit = ovlimit;

	dql->prev_last_obj_cnt = dql->last_obj_cnt;

	dql->prev_last_obj_cnt = READ_ONCE(dql->last_obj_cnt);

	dql->num_completed = completed;

	dql->prev_num_queued = num_queued;