Aditya Gupta reported PowerPC crashes bisected to the blamed commit. Apparently some platforms do not allow prefetch() on arbitrary pointers. prefetch(next); prefetch(&next->priority); // CRASH when next == NULL Only NULL seems to be supported, with specific handling in prefetch(). Add a conditional to avoid the two prefetches and the skb->next clearing for the last skb in the list. Fixes: b2e9821cff6c ("net: prefech skb->priority in __dev_xmit_skb()") Reported-by: Aditya Gupta Closes: https://lore.kernel.org/netdev/e9f4abee-b132-440f-a50e-bced0868b5a7@linux.ibm.com/T/#mddc372b64ec5a3b181acc9ee3909110c391cc18a Signed-off-by: Eric Dumazet --- net/core/dev.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 9094c0fb8c68..36dc5199037e 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4241,9 +4241,11 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, int count = 0; llist_for_each_entry_safe(skb, next, ll_list, ll_node) { - prefetch(next); - prefetch(&next->priority); - skb_mark_not_on_list(skb); + if (next) { + prefetch(next); + prefetch(&next->priority); + skb_mark_not_on_list(skb); + } rc = dev_qdisc_enqueue(skb, q, &to_free, txq); count++; } -- 2.52.0.313.g674ac2bdf7-goog