6.12-stable review patch. If anyone has any objections, please let me know.
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From: Ido Schimmel idosch@nvidia.com
[ Upstream commit 811b8f534fd85e17077bd2ac0413bcd16cc8fb9b ]
In case of tc offload, when user space queries the kernel for tc action statistics, tc will query the offloaded statistics from device drivers. Among other statistics, drivers are expected to pass the number of packets that hit the action since the last query as a 64-bit number.
Unfortunately, tc treats the number of packets as a 32-bit number, leading to truncation and incorrect statistics when the number of packets since the last query exceeds 0xffffffff:
$ tc -s filter show dev swp2 ingress filter protocol all pref 1 flower chain 0 filter protocol all pref 1 flower chain 0 handle 0x1 skip_sw in_hw in_hw_count 1 action order 1: mirred (Egress Redirect to device swp1) stolen index 1 ref 1 bind 1 installed 58 sec used 0 sec Action statistics: Sent 1133877034176 bytes 536959475 pkt (dropped 0, overlimits 0 requeues 0) [...]
According to the above, 2111-byte packets were redirected which is impossible as only 64-byte packets were transmitted and the MTU was 1500.
Fix by treating packets as a 64-bit number:
$ tc -s filter show dev swp2 ingress filter protocol all pref 1 flower chain 0 filter protocol all pref 1 flower chain 0 handle 0x1 skip_sw in_hw in_hw_count 1 action order 1: mirred (Egress Redirect to device swp1) stolen index 1 ref 1 bind 1 installed 61 sec used 0 sec Action statistics: Sent 1370624380864 bytes 21416005951 pkt (dropped 0, overlimits 0 requeues 0) [...]
Which shows that only 64-byte packets were redirected (1370624380864 / 21416005951 = 64).
Fixes: 380407023526 ("net/sched: Enable netdev drivers to update statistics of offloaded actions") Reported-by: Joe Botha joe@atomic.ac Signed-off-by: Ido Schimmel idosch@nvidia.com Reviewed-by: Petr Machata petrm@nvidia.com Reviewed-by: Simon Horman horms@kernel.org Link: https://patch.msgid.link/20250204123839.1151804-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/sch_generic.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 1e6324f0d4efd..24e48af7e8f74 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -851,7 +851,7 @@ static inline int qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, }
static inline void _bstats_update(struct gnet_stats_basic_sync *bstats, - __u64 bytes, __u32 packets) + __u64 bytes, __u64 packets) { u64_stats_update_begin(&bstats->syncp); u64_stats_add(&bstats->bytes, bytes);