On Thursday 21 August 2008, you wrote:
>
> :so_error:
> : The process-side code only ever sets it to 0.
> : I'm thinking I should add a sequence number, incremented every
> : time the proto thread sets so_error. That way, the user side
> : doesn't need to set it to 0 all the time.
>
> There is somewhat of an async race here but it doesn't look like
> the original code really cared about potential races, so I think
> we can avoid the ref count. If we really needed we could use
> the load-and-clear atomic op (I forget exactly what it is).
The seq count should be cheaper than an atomic op though :)
> :so_sigio: set/unset in process context. proto tests so_sigio and then
> : uses it. This means it can be free()d from under us.
> : Easier way is probably to add a new netmsg to set/clear
> : ->so_sigio.
>
> This works for me. SIGIO is almost never used so I don't care how
> inefficient it winds up being.
>
> :so_oobmark: soreceive, tcp_input (XXX: should be pretty rare. spinlock?)
>
> TCP guarantees one OOB mark at a time, so I think this can just
> be a rbytes/wbytes index and that will deal with the race.
Have to think about it. The main issue here is that the interface for
receiving oob data is *horrible* but, alas, we have to live with that.
> :so_aiojobq: used by aio only, which runs under the mplock anyway
>
> Yah.
>
> :so_upcall{,arg}: XXX accf. netgraph sock, nfs sock should be ok
> : gets modified in soisconnected() and withing the upcalls
> : which get run by soisconnected() and sowakeup(). So all
> : modifications are made in proto thread context and so
> : are all accesses. I guess we're safe. accf_data and
> : accf_http mess with the sockbuf, but that socket hasn't
> : been connected yet, so userspace can't access it. IOW,
> : I think running without the BGL is ok here. Not so for
> : netgraph and nfs/smb callbacks. Take the BGL there.
>
> I think the socket code is safe, but the NFS code might not be
> with regards to running without the BGL. That portion of the NFS
> code could be spin-locked fairly easily.
Well, my intention was to take the BGL in the nfs/smb and netgraph upcalls
for now.
Thanks,
Aggelos
