Messages in this thread |  | | Subject | Re: [PATCH] block: aoenet: Replace GFP_ATOMIC with GFP_KERNEL in aoenet_rcv | From | Jia-Ju Bai <> | Date | Sun, 28 Jan 2018 10:12:51 +0800 |
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On 2018/1/28 1:48, Ed Cashin wrote: > If the tool cannot tell whether the protected state is manipulated by *another* piece of code called in atomic context, then it's insufficient. > >> On Jan 26, 2018, at 4:37 AM, Jia-Ju Bai <baijiaju1990@gmail.com> wrote: >> >> After checking all possible call chains to aoenet_rcv(), >> my tool finds that aoenet_rcv() is never called in atomic context, >> namely never in an interrupt handler or holding a spinlock. >> Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL. >> >> This is found by a static analysis tool named DCNS written by myself. >> >> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> >> --- >> drivers/block/aoe/aoenet.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/block/aoe/aoenet.c b/drivers/block/aoe/aoenet.c >> index 63773a9..d5fff7a 100644 >> --- a/drivers/block/aoe/aoenet.c >> +++ b/drivers/block/aoe/aoenet.c >> @@ -138,7 +138,7 @@ static int __init aoe_iflist_setup(char *str) >> if (dev_net(ifp) != &init_net) >> goto exit; >> >> - skb = skb_share_check(skb, GFP_ATOMIC); >> + skb = skb_share_check(skb, GFP_KERNEL); >> if (skb == NULL) >> return 0; >> if (!is_aoe_netif(ifp)) >> -- >> 1.7.9.5 >> >>
Sorry, I find my report is false positive after I manually check the code. aoenet_rcv() is used as function pointer via "->func", and it is called in dev_queue_xmit_nit() in net/core/dev.c. dev_queue_xmit_nit() calls a rcu_read_lock() before it calls pt_prev->func(). Thus it is right to use GFP_ATOMIC in aoenet_rcv(). Sorry again for my incorrect report...
Thanks, Jia-Ju Bai
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