> On 4 Aug 2022, at 18:05, Vitaliy Makkoveev <[email protected]> wrote:
>
> On Thu, Aug 04, 2022 at 01:42:48PM +0200, Alexander Bluhm wrote:
>> On Thu, Aug 04, 2022 at 02:18:49AM +0300, Vitaliy Makkoveev wrote:
>>> Also, I like to have exclusive layer locks like `tcp_lock???,
>>> `udp_lock???, etc.. And take them with shared netlock held as the
>>> first step of inet sockets unlocking.
>>
>> With PRU_LOCK and PRU_UNLOCK each layer can decide itself which
>> kind is appropriate. For divert packet per PCB lock is trivial.
>> For loops delivering to all sockets like UDP multicast or RAW
>> sockets, a mutex per layer an easier start.
>>
>>>> sblock()/sbunlock() relie on exclusive socket or layer lock,
>>>> which protects `sb_flags??? modification. This diff breaks them,
>>>> because nothing stops concurrent soreceive() threads to set
>>>> SB_LOCK flag and and be sure that socket buffer is locked.
>>
>> Either sb_flags is protected by the exclusice netlock or by a shared
>> netlock and PCB mutex. So only one thread can access them. Right?
>>
>
> Yes, you are right, I missed the PRU_LOCK/PRU_UNLOCK calls.
>
> With your diff, sbwait() releases only netlock and leaves `inp_mtx'
> locked. So when we enter sbwait() in the soreceive() path, the
> concurrent sbappendaddr() thread will spin instead of append mbut to
> `so_rcv'.
>
> It seems sbwait() should release `inp_mtx' and keep shared netlock
> locked.
Both of netlock and `inp_mtx’ should be released by sbwait(). This
is fully identical to current behaviour.
