On Fri, Jun 07, 2013 at 09:34:23PM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch changes vhost_scsi_free_cmd() to call transport_generic_free_cmd()
> with wait_for_tasks=false in order to avoid the extra se_cmd->t_state_lock
> access for the wait_for_tasks=true case.
>
> This is unnecessary because vhost_scsi_free_cmd() is only ever called by
> vhost_scsi_complete_cmd_work() after TCM completion handoff, and by
> vhost_scsi_handle_vq() exception code before TCM submission handoff, so
> there is never a case where se_cmd is still active from TCM's perspective
> when transport_generic_free_cmd() is called.
>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Roland Dreier <roland@xxxxxxxxxx>
> Cc: Kent Overstreet <koverstreet@xxxxxxxxxx>
> Cc: Asias He <asias@xxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
> Cc: Moussa Ba <moussaba@xxxxxxxxxx>
> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Acked-by: Asias He <asias@xxxxxxxxxx>
> ---
> drivers/vhost/scsi.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
> index 7014202..aacf71e 100644
> --- a/drivers/vhost/scsi.c
> +++ b/drivers/vhost/scsi.c
> @@ -557,7 +557,7 @@ static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
> struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
>
> /* TODO locking against target/backend threads? */
> - transport_generic_free_cmd(se_cmd, 1);
> + transport_generic_free_cmd(se_cmd, 0);
>
> if (tv_cmd->tvc_sgl_count) {
> u32 i;
> --
> 1.7.2.5
>
--
Asias
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