[Drbd-dev] DRBD8: disconnecting while already disconnecting can hang the receiver

[Philipp Reisner]

On Tuesday 27 November 2007 14:06:46 Montrose, Ernest wrote:
> Phil,
> I looked at my notes...To reproduce this you can fake the condition this
> way:
> * Issue a disconnect on node0 for r5.
> * Locally on node1 we will get into drbd_receiver.c:drbd_disconnect()
> and while there in drbd_disconnect() (Put a small delay there or
> something); issue a "drbdsetup /dev/drbd5 disconnect".
>
> This last drbdsetup will time out with " No response from the DRBD
> driver! Is the module loaded?"
> But the driver will be waiting forever in
> drbd_nl.c:drbd_nl_disconnect().
>

Yes. This is what I tested. I had a delay in drbd_disconenct(). 
I did not managed to get it into troubles.

BTW, while looking at the patch, I would have done it like this:

@@ -589,7 +589,8 @@ STATIC int is_valid_state_transition(drbd_dev* 
mdev,drbd_state_t ns,drbd_state_t
        if( (ns.conn == StartingSyncT || ns.conn == StartingSyncS ) &&
            os.conn > Connected) rv=SS_ResyncRunning;

-       if( ns.conn == Disconnecting && os.conn == StandAlone)
+       if ( ns.conn == Disconnecting &&
+            ( os.conn == StandAlone || os.conn == TearDown ) )
                rv=SS_AlreadyStandAlone;

        if( ns.disk > Attaching && os.disk == Diskless)

-Phil
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