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net: fix call location in kfree_skb_list_reason

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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 c205cc7534
("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 <saeed@kernel.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jesper Dangaard Brouer 2023-01-13 14:51:59 +01:00 committed by Paolo Abeni
parent 501543b4ff
commit a4650da2a2
1 changed files with 21 additions and 13 deletions
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34
net/core/skbuff.c
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@ -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;
}
}