[dm-devel] [PATCH v2 1/5] dm mpath: only try to load the scsi_dh module if the scsi_dh doesn't exist

[Chandra Seetharaman]

Reviewed-by: Chandra Seetharaman <sekharan at us.ibm.com>

On Tue, 2012-05-08 at 17:56 -0400, Mike Snitzer wrote:
> There have been reports of multipath table loads hanging due to
> __request_module hanging (for some unknown reason).
> 
> More often than not, the scsi_dh is already available and there is no
> need to request_module().
> 
> Reported-by: Ben Marzinski <bmarzins at redhat.com>
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> ---
>  drivers/md/dm-mpath.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index 922a338..754f38f 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -718,8 +718,8 @@ static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
>  		return 0;
> 
>  	m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
> -	request_module("scsi_dh_%s", m->hw_handler_name);
> -	if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
> +	if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
> +				     "scsi_dh_%s", m->hw_handler_name)) {
>  		ti->error = "unknown hardware handler type";
>  		ret = -EINVAL;
>  		goto fail;