Commit 6c131d0c authored Jun 06, 2013 by Nicholas Bellinger

vhost/scsi: Drop unnecessary wait_for_tasks=true usage with transport_generic_free_cmd



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@lst.de>
Cc: Roland Dreier <roland@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Asias He <asias@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Moussa Ba <moussaba@micron.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

parent ca24976a

drivers/vhost/scsi.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -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;		struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;

	/* TODO locking against target/backend threads? */		/* 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) {		if (tv_cmd->tvc_sgl_count) {
	u32 i;		u32 i;