On 3/5/19 7:44 PM, Eric Dumazet wrote:
> On Tue, Mar 5, 2019 at 7:11 AM Eric Dumazet <eduma...@google.com> wrote:
>>> My original suggestion was to use VM_WARN_ONCE() so that the debug checks
>>> would
>>> be compiled out by the compiler, unless you compile a debug kernel.
>>>
>>> Something like :
>>>
>>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>>> index
>>> ad07dd71063da09843ccfbd3e00d3f41567e1205..889563a66dde2a41c198d92a80183cf5382f632d
>>> 100644
>>> --- a/net/ipv4/tcp.c
>>> +++ b/net/ipv4/tcp.c
>>> @@ -943,6 +943,9 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page
>>> *page, int offset,
>>> ssize_t copied;
>>> long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
>>>
>>> + if (VM_WARN_ONCE(PageSlab(page)), "page must not be a Slab one")
>>> + return -EINVAL;
>>> +
>
> Well, VM_WARN_ONCE() returns 1 if !CONFIG_DEBUG_VM,
> so it is not behaving like WARN_ONCE(), which is unfortunate.
>
> But you get the idea ;)
Thanks, I did not know this trick.
Seems it can be replaced by following construction, I'll check it tomorrow
morning.
#ifdef CONFIG_DEBUG_VM
if (WARN_ONCE(PageSlab(page), "page must not be a Slab one")
return -EINVAL;
#endif
I expect it should affect debug kernels only,
fail all incorrect requests, taint the kernel and generate warning only once.
>>> * (passive side) where data is allowed to be sent before a
>>> connection
>>> * is fully established.
>>>
>>>
>>> For some reason you added a fallback :/
>>>
>
