Re: [PATCH 02/12] scsi_transport_srp: Fix a race condition

Sagi Grimberg
2015-04-30T09:44:15Z

On 4/30/2015 11:57 AM, Bart Van Assche wrote:
> Avoid that srp_terminate_io() can get invoked while srp_queuecommand()
> is in progress. This patch avoids that an I/O timeout can trigger the
> following kernel warning:
>
> WARNING: at drivers/infiniband/ulp/srp/ib_srp.c:1447 srp_terminate_io+0xef/0x100 [ib_srp]()
> Call Trace:
> [<ffffffff814c65a2>] dump_stack+0x4e/0x68
> [<ffffffff81051f71>] warn_slowpath_common+0x81/0xa0
> [<ffffffff8105204a>] warn_slowpath_null+0x1a/0x20
> [<ffffffffa075f51f>] srp_terminate_io+0xef/0x100 [ib_srp]
> [<ffffffffa07495da>] __rport_fail_io_fast+0xba/0xc0 [scsi_transport_srp]
> [<ffffffffa0749a90>] rport_fast_io_fail_timedout+0xe0/0xf0 [scsi_transport_srp]
> [<ffffffff8106e09b>] process_one_work+0x1db/0x780
> [<ffffffff8106e75b>] worker_thread+0x11b/0x450
> [<ffffffff81073c64>] kthread+0xe4/0x100
> [<ffffffff814cf26c>] ret_from_fork+0x7c/0xb0
>
> See also patch "scsi_transport_srp: Add transport layer error
> handling" (commit ID 29c17324803c).
>
> Signed-off-by: Bart Van Assche <bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
> Cc: James Bottomley <JBottomley-O3H1v1f1dlM@public.gmane.org>
> Cc: Sagi Grimberg <sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> Cc: Sebastian Parschauer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
> Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> #v3.13
> ---
> drivers/scsi/scsi_transport_srp.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
> index 6ce1c48..4a44337 100644
> --- a/drivers/scsi/scsi_transport_srp.c
> +++ b/drivers/scsi/scsi_transport_srp.c
> @@ -437,8 +437,10 @@ static void __rport_fail_io_fast(struct srp_rport *rport)
>
> /* Involve the LLD if possible to terminate all I/O on the rport. */
> i = to_srp_internal(shost->transportt);
> - if (i->f->terminate_rport_io)
> + if (i->f->terminate_rport_io) {
> + srp_wait_for_queuecommand(shost);
> i->f->terminate_rport_io(rport);
> + }

Why not just terminate the inflight IO before unblocking the target?
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