On Thu, Sep 20, 2012 at 12:20:38PM -0700, Tejun Heo wrote:
> On Thu, Sep 20, 2012 at 03:17:16PM -0400, Vivek Goyal wrote:
> > I suspect we are looping in retry code because bio based queues never come
> > out of bypass mode.
> >
> > /*
> > * If queue was bypassing, we should retry. Do so after a
> > * short msleep(). It isn't strictly necessary but queue
> > * can be bypassing for some time and it's always nice to
> > * avoid busy looping.
> > */
> > if (ret == -EBUSY) {
> > msleep(10);
> > ret = restart_syscall();
> > }
>
> Yeah, I incorrectly assumed that bio based drivers would call
> blk_init_allocated_queue(). I think we need to move the initial
> bypass_end call to blk_register_queue(). Like the following. Not
> completely sure yet tho.
I can confirm that with this patch, hang issue is gone. I tried it on
a dm device.
Thanks
Vivek
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 4b4dbdf..cbb019a 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -714,9 +714,6 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
> return NULL;
>
> blk_queue_congestion_threshold(q);
> -
> - /* all done, end the initial bypass */
> - blk_queue_bypass_end(q);
> return q;
> }
> EXPORT_SYMBOL(blk_init_allocated_queue);
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 9628b29..f53802e 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -527,6 +527,8 @@ int blk_register_queue(struct gendisk *disk)
> if (WARN_ON(!q))
> return -ENXIO;
>
> + blk_queue_bypass_end(q);
> +
> ret = blk_trace_init_sysfs(dev);
> if (ret)
> return ret;
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