From a4650da2a2d6150a8ff1ea36fde9f6a26cf5fda3 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Fri, 13 Jan 2023 14:51:59 +0100 Subject: [PATCH] net: fix call location in kfree_skb_list_reason The SKB drop reason uses __builtin_return_address(0) to give the call "location" to trace_kfree_skb() tracepoint skb:kfree_skb. To keep this stable for compilers kfree_skb_reason() is annotated with __fix_address (noinline __noclone) as fixed in commit c205cc7534a9 ("net: skb: prevent the split of kfree_skb_reason() by gcc"). The function kfree_skb_list_reason() invoke kfree_skb_reason(), which cause the __builtin_return_address(0) "location" to report the unexpected address of kfree_skb_list_reason. Example output from 'perf script': kpktgend_0 1337 [000] 81.002597: skb:kfree_skb: skbaddr=0xffff888144824700 protocol=2048 location=kfree_skb_list_reason+0x1e reason: QDISC_DROP Patch creates an __always_inline __kfree_skb_reason() helper call that is called from both kfree_skb_list() and kfree_skb_list_reason(). Suggestions for solutions that shares code better are welcome. As preparation for next patch move __kfree_skb() invocation out of this helper function. Reviewed-by: Saeed Mahameed Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Paolo Abeni --- net/core/skbuff.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 3a10387f9434..ca2b4d6f9c9a 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -930,6 +930,21 @@ void __kfree_skb(struct sk_buff *skb) } EXPORT_SYMBOL(__kfree_skb); +static __always_inline +bool __kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason) +{ + if (unlikely(!skb_unref(skb))) + return false; + + DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX); + + if (reason == SKB_CONSUMED) + trace_consume_skb(skb); + else + trace_kfree_skb(skb, __builtin_return_address(0), reason); + return true; +} + /** * kfree_skb_reason - free an sk_buff with special reason * @skb: buffer to free @@ -942,26 +957,19 @@ EXPORT_SYMBOL(__kfree_skb); void __fix_address kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason) { - if (unlikely(!skb_unref(skb))) - return; - - DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX); - - if (reason == SKB_CONSUMED) - trace_consume_skb(skb); - else - trace_kfree_skb(skb, __builtin_return_address(0), reason); - __kfree_skb(skb); + if (__kfree_skb_reason(skb, reason)) + __kfree_skb(skb); } EXPORT_SYMBOL(kfree_skb_reason); -void kfree_skb_list_reason(struct sk_buff *segs, - enum skb_drop_reason reason) +void __fix_address +kfree_skb_list_reason(struct sk_buff *segs, enum skb_drop_reason reason) { while (segs) { struct sk_buff *next = segs->next; - kfree_skb_reason(segs, reason); + if (__kfree_skb_reason(segs, reason)) + __kfree_skb(segs); segs = next; } } -- 2.34.1