problem with function vlan_get_protocol()

Hi,all

in file inclue/linux/if_vlan.h

there is a statement in function vlan_get_protocol()

	if (likely(protop))
		protocol = *protop;

do we need an else branch on pointer protop failed ? through the else is unlikely

	if (likely(protop))
		protocol = *protop;
    else
		protocol = proto;

is it necessary ?

thanks

2011-07-17
jiangtao.jit

jiangtao.jit <[email protected]> :
[...]

The else branch signals that skb_header_pointer uncloaked a really tiny ethernet frame : the content of proto is not even initialized (stack allocation), whence irrelevant. In such circumstances the default initialization value of protocol (0) does not seem too bad.

Ueimor

Thanks a lot Francois
thank you for your explanation

--
jiangtao

发件人： Francois Romieu
发送时间： 2011-07-17 15:49:00
收件人： jiangtao.jit
抄送： netdev
主题： Re: problem with function vlan_get_protocol()

jiangtao.jit <[email protected]> :
[...]

The else branch signals that skb_header_pointer uncloaked a really tiny ethernet frame : the content of proto is not even initialized (stack allocation), whence irrelevant. In such circumstances the default initialization value of protocol (0) does not seem too bad.

Ueimor