Seeing EINVAL from writev on 8.0 to a non-blocking socket even though the data seems to hit the wire

[Eitan Adler]

On 2 May 2013 20:00, Richard Sharpe <realrichardsharpe at gmail.com> wrote:
> On Thu, May 2, 2013 at 7:52 AM, Eric van Gyzen <eric at vangyzen.net> wrote:
>> On 05/02/2013 08:48, Richard Sharpe wrote:
>>> On Wed, May 1, 2013 at 9:34 PM, Alfred Perlstein <bright at mu.org> wrote:
>>>> On 5/1/13 8:03 PM, Richard Sharpe wrote:
>>>>> Hi folks,
>>>>>
>>>>> I am checking to see if there are any known bugs with respect to this
>>>>> in FreeBSD 8.0.
>>>>>
>>>>> Situation is that Samba 3.6.6 uses writev to a non-blocking socket to
>>>>> get the SMB2 requests on the wire.
>>>>>
>>>>> Intermittently, we see the writev return EINVAL even though the data
>>>>> has gotten on the wire. This I have verified by grabbing a capture and
>>>>> comparing the SMB Sequence number in the last outgoing packet on the
>>>>> wire vs the in-memory contents when we get EINVAL.
>>>>>
>>>>> Sometimes it occurs on a four-element IOVEC, sometimes we get EAGAIN
>>>>> on the four-element IOVEC and then we get EINVAL when retrying on a
>>>>> smaller IOVEC.
>>>>>
>>>>> Where should I look to check if there is some path where this might be
>>>>> happening? Is this even the correct mailing list?
>>>>>
>>>> What does the iovec look like when you get EINVAL? Can you sanity check
>>>> it? Is there anything special about it? (zero length vecs?)
>>>>
>>>> I think there are a few "maxvals" that if overrun cause EINVAL to be
>>>> returned. example is if your iovec is somehow huge or has many, many
>>>> elements.
>>> Can anyone tell me the call graph down to the TCP code?
>>>
>>
>> writev kern/sys_generic.c
>> kern_writev
>> dofilewrite
>> fo_write in sys/file.h
>> soo_write in kern/sys_socket.c
>> sosend in kern/uipc_socket.c
>> sosend_generic
>> tcp_usr_send in netinet/tcp_usrreq.c
>
> Is there a tool that generates call graphs?

gprof in base
valgrind --callgrind
doxygen can also do this.

there are probably others.


-- 
Eitan Adler