Hi Greg,
> On Oct 8, 2024, at 3:36 AM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Fri, Oct 04, 2024 at 10:03:27AM -0700, Sherry Yang wrote:
>> From: Eric Dumazet <edumazet@xxxxxxxxxx>
>>
>> [ Upstream commit 1fb2d41501f38192d8a19da585cd441cf8845697 ]
>>
>> pskb_may_pull() can fail for two different reasons.
>>
>> Provide pskb_may_pull_reason() helper to distinguish
>> between these reasons.
>>
>> It returns:
>>
>> SKB_NOT_DROPPED_YET : Success
>> SKB_DROP_REASON_PKT_TOO_SMALL : packet too small
>> SKB_DROP_REASON_NOMEM : skb->head could not be resized
>>
>> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
>> Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
>> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
>> Stable-dep-of: 8bd67ebb50c0 ("net: bridge: xmit: make sure we have at least eth header len bytes")
>> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
>> [Sherry: bp to 5.15.y. Minor conflicts due to missing commit
>> d427c8999b07 ("net-next: skbuff: refactor pskb_pull") which is not
>> necessary in 5.15.y. Ignore context change.
>> Signed-off-by: Sherry Yang <sherry.yang@xxxxxxxxxx>
>> ---
>> include/linux/skbuff.h | 19 +++++++++++++++----
>> 1 file changed, 15 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index b230c422dc3b..f92e8fe4f5eb 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -2465,13 +2465,24 @@ static inline void *pskb_pull(struct sk_buff *skb, unsigned int len)
>> return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
>> }
>>
>> -static inline bool pskb_may_pull(struct sk_buff *skb, unsigned int len)
>> +static inline enum skb_drop_reason
>> +pskb_may_pull_reason(struct sk_buff *skb, unsigned int len)
>> {
>> if (likely(len <= skb_headlen(skb)))
>> - return true;
>> + return SKB_NOT_DROPPED_YET;
>> +
>> if (unlikely(len > skb->len))
>> - return false;
>> - return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
>> + return SKB_DROP_REASON_PKT_TOO_SMALL;
>> +
>> + if (unlikely(!__pskb_pull_tail(skb, len - skb_headlen(skb))))
>> + return SKB_DROP_REASON_NOMEM;
>> +
>> + return SKB_NOT_DROPPED_YET;
>> +}
>> +
>> +static inline bool pskb_may_pull(struct sk_buff *skb, unsigned int len)
>> +{
>> + return pskb_may_pull_reason(skb, len) == SKB_NOT_DROPPED_YET;
>> }
>>
>> void skb_condense(struct sk_buff *skb);
>> --
>> 2.46.0
>>
>>
>
> Any specific reason why you didn't test build this patch?
>
> It breaks the build into thousands of tiny pieces.
Sorry about the build failure. We have a branch which was forked from 5.15.y, and I did build and some smoke tests there. The build and smoke tests passed on our branch. However, I didn’t notice our branch backported prerequisite commits which made it diverge from linux-stable 5.15.y. I will apply the patch to upstream/linux-stable and build there before I send patch to upstream/linux-stable next time.
Sorry about the inconvenience.
Sherry
>
> greg k-h
