Re: [PATCH] fnic: to not call 'scsi_done()' for unhandled commands

[Laurence Oberman <loberman@redhat.com>]

On Fri, 2020-05-15 at 15:52 +0200, Hannes Reinecke wrote:
> On 5/15/20 3:06 PM, Laurence Oberman wrote:
> > On Fri, 2020-05-15 at 13:26 +0200, Hannes Reinecke wrote:
> > > The fnic drivers assigns an ioreq structure to each command, and
> > > severs this assignment once scsi_done() has been called and the
> > > command has been completed.
> > > So when traversing commands to terminate outstanding I/O we
> > > should
> > > not call scsi_done() on commands which do not have a
> > > corresponding
> > > ioreq structure; these commands have either never entered the
> > > driver
> > > or have already been completed.
> > > 
> > > Signed-off-by: Hannes Reinecke <hare@suse.com>
> > > ---
> > >   drivers/scsi/fnic/fnic_scsi.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/scsi/fnic/fnic_scsi.c
> > > b/drivers/scsi/fnic/fnic_scsi.c
> > > index 27535c90b248..8d2798cbd30f 100644
> > > --- a/drivers/scsi/fnic/fnic_scsi.c
> > > +++ b/drivers/scsi/fnic/fnic_scsi.c
> > > @@ -1401,7 +1401,7 @@ static void fnic_cleanup_io(struct fnic
> > > *fnic,
> > > int exclude_id)
> > >   		}
> > >   		if (!io_req) {
> > >   			spin_unlock_irqrestore(io_lock, flags);
> > > -			goto cleanup_scsi_cmd;
> > > +			continue;
> > >   		}
> > >   
> > >   		CMD_SP(sc) = NULL;
> > 
> > Hi Hannes,
> > Thanks for this patch, but can you share what the impact was of
> > this
> > issue.
> > What diod you see in logs/behavior
> > 
> 
> Unmap the LUNs from the array, and reboot the machine.
> Causing a nice kernel oops in fnic_terminate_rport_io:
> 
> [   41.904013]  rport-3:0-2: blocked FC remote port time out:
> removing rport
> [   41.911625] BUG: kernel NULL pointer dereference, address: 
> 0000000000000040
> [   41.919408] #PF: supervisor read access in kernel mode
> [   41.919409] #PF: error_code(0x0000) - not-present page
> [   41.919411] PGD 0 P4D 0
> [   41.919416] Oops: 0000 [#1] SMP PTI
> [   41.919420] CPU: 1 PID: 219 Comm: kworker/1:1 Kdump: loaded
> Tainted: 
> G               X   5.3.18-16-default #1 SLE15-SP2 (unreleased)
> [   41.919421] Hardware name: Cisco Systems Inc 
> UCSC-C220-M3S/UCSC-C220-M3S, BIOS C220M3.3.0.4e.0.1106191007
> 11/06/2019
> [   41.919433] Workqueue: fc_wq_3 fc_rport_final_delete
> [scsi_transport_fc]
> [   41.919443] RIP: 0010:fnic_terminate_rport_io+0x2db/0x6c0 [fnic]
> [   41.919446] Code: 3c c2 e8 48 00 95 f5 48 85 c0 49 89 c5 74 2c 48
> 05 
> 20 01 00 00 48 89 44 24 10 74 1f 49 8b 85 58 01 00 00 48 8b 80 c0 01
> 00 
> 00 <48> 8b 78 40 e8 1c 0f e4 ff 85 c0 0f 85 b2 fd ff ff 4c 89 e6 48
> 89
> [   41.919448] RSP: 0018:ffffa521c164bde0 EFLAGS: 00010082
> [   41.919450] RAX: 0000000000000000 RBX: ffff8c33633587c8 RCX: 
> ffff8c3363358bc0
> [   41.919452] RDX: ffff8c336347bc80 RSI: 0000000000000080 RDI: 
> ffff8c33632dd8c0
> [   41.919453] RBP: ffff8c3363359208 R08: 00335f71775f6366 R09: 
> 8080808080808080
> [   41.919455] R10: ffffa521c0087dc8 R11: fefefefefefefeff R12: 
> 0000000000000246
> [   41.919456] R13: ffff8c33633e8100 R14: ffff8c24470a4000 R15: 
> 0000000000000080
> [   41.919459] FS:  0000000000000000(0000) GS:ffff8c33bfa40000(0000) 
> knlGS:0000000000000000
> [   41.919461] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   41.919466] CR2: 0000000000000040 CR3: 000000011340a003 CR4: 
> 00000000000606e0
> [   42.066910] Call Trace:
> [   42.066929]  fc_terminate_rport_io+0x51/0x70 [scsi_transport_fc]
> [   42.066935]  fc_rport_final_delete+0x53/0x1e0 [scsi_transport_fc]
> [   42.066943]  process_one_work+0x1f4/0x3e0
> [   42.066947]  worker_thread+0x2d/0x3e0
> [   42.066951]  ? process_one_work+0x3e0/0x3e0
> [   42.066954]  kthread+0x10d/0x130
> [   42.066957]  ? kthread_park+0xa0/0xa0
> [   42.066961]  ret_from_fork+0x35/0x40
> 
> Cheers,
> 
> Hannes

Awesome, Ok Thank you!
I looked at the patch and it looks correct to me at least.
I will add a Review but prob best to have the Cisco fnic folks also
review.
Thank you for catching this.

Reviewed-by: Laurence Oberman <loberman@redhat.com>