| Message ID | 1497084579-32434-1-git-send-email-baijiaju1990@163.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Jia-Ju Bai <baijiaju1990@163.com> Date: Sat, 10 Jun 2017 16:49:39 +0800 > The kernel may sleep under a rcu read lock in cfpkt_create_pfx, and the > function call path is: > cfcnfg_linkup_rsp (acquire the lock by rcu_read_lock) > cfctrl_linkdown_req > cfpkt_create > cfpkt_create_pfx > alloc_skb(GFP_KERNEL) --> may sleep > cfserl_receive (acquire the lock by rcu_read_lock) > cfpkt_split > cfpkt_create_pfx > alloc_skb(GFP_KERNEL) --> may sleep > > There is "in_interrupt" in cfpkt_create_pfx to decide use "GFP_KERNEL" or > "GFP_ATOMIC". In this situation, "GFP_KERNEL" is used because the function > is called under a rcu read lock, instead in interrupt. > > To fix it, only "GFP_ATOMIC" is used in cfpkt_create_pfx. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com> Applied and queued up for -stable.
diff --git a/net/caif/cfpkt_skbuff.c b/net/caif/cfpkt_skbuff.c index 59ce1fc..71b6ab2 100644 --- a/net/caif/cfpkt_skbuff.c +++ b/net/caif/cfpkt_skbuff.c @@ -81,11 +81,7 @@ static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx) { struct sk_buff *skb; - if (likely(in_interrupt())) - skb = alloc_skb(len + pfx, GFP_ATOMIC); - else - skb = alloc_skb(len + pfx, GFP_KERNEL); - + skb = alloc_skb(len + pfx, GFP_ATOMIC); if (unlikely(skb == NULL)) return NULL;
The kernel may sleep under a rcu read lock in cfpkt_create_pfx, and the function call path is: cfcnfg_linkup_rsp (acquire the lock by rcu_read_lock) cfctrl_linkdown_req cfpkt_create cfpkt_create_pfx alloc_skb(GFP_KERNEL) --> may sleep cfserl_receive (acquire the lock by rcu_read_lock) cfpkt_split cfpkt_create_pfx alloc_skb(GFP_KERNEL) --> may sleep There is "in_interrupt" in cfpkt_create_pfx to decide use "GFP_KERNEL" or "GFP_ATOMIC". In this situation, "GFP_KERNEL" is used because the function is called under a rcu read lock, instead in interrupt. To fix it, only "GFP_ATOMIC" is used in cfpkt_create_pfx. Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com> --- net/caif/cfpkt_skbuff.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)