From bb3e74b92f723ab7d1ab07a17807fd7f75f2c3ed Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Wed, 8 Oct 2014 06:19:20 +0000 Subject: [PATCH] vhost-scsi: Take configfs group dependency during VHOST_SCSI_SET_ENDPOINT commit ab8edab132829b26dd13db6caca3c242cce35dc1 upstream. This patch addresses a bug where individual vhost-scsi configfs endpoint groups can be removed from below while active exports to QEMU userspace still exist, resulting in an OOPs. It adds a configfs_depend_item() in vhost_scsi_set_endpoint() to obtain an explicit dependency on se_tpg->tpg_group in order to prevent individual vhost-scsi WWPN endpoints from being released via normal configfs methods while an QEMU ioctl reference still exists. Also, add matching configfs_undepend_item() in vhost_scsi_clear_endpoint() to release the dependency, once QEMU's reference to the individual group at /sys/kernel/config/target/vhost/$WWPN/$TPGT is released. (Fix up vhost_scsi_clear_endpoint() error path - DanC) Cc: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Stefan Hajnoczi Signed-off-by: Nicholas Bellinger Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/scsi.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index e48d4a6..5d0b7b8 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -1200,6 +1200,7 @@ static int vhost_scsi_set_endpoint(struct vhost_scsi *vs, struct vhost_scsi_target *t) { + struct se_portal_group *se_tpg; struct tcm_vhost_tport *tv_tport; struct tcm_vhost_tpg *tpg; struct tcm_vhost_tpg **vs_tpg; @@ -1247,6 +1248,21 @@ vhost_scsi_set_endpoint(struct vhost_scsi *vs, ret = -EEXIST; goto out; } + /* + * In order to ensure individual vhost-scsi configfs + * groups cannot be removed while in use by vhost ioctl, + * go ahead and take an explicit se_tpg->tpg_group.cg_item + * dependency now. + */ + se_tpg = &tpg->se_tpg; + ret = configfs_depend_item(se_tpg->se_tpg_tfo->tf_subsys, + &se_tpg->tpg_group.cg_item); + if (ret) { + pr_warn("configfs_depend_item() failed: %d\n", ret); + kfree(vs_tpg); + mutex_unlock(&tpg->tv_tpg_mutex); + goto out; + } tpg->tv_tpg_vhost_count++; tpg->vhost_scsi = vs; vs_tpg[tpg->tport_tpgt] = tpg; @@ -1289,6 +1305,7 @@ static int vhost_scsi_clear_endpoint(struct vhost_scsi *vs, struct vhost_scsi_target *t) { + struct se_portal_group *se_tpg; struct tcm_vhost_tport *tv_tport; struct tcm_vhost_tpg *tpg; struct vhost_virtqueue *vq; @@ -1337,6 +1354,13 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs, vs->vs_tpg[target] = NULL; match = true; mutex_unlock(&tpg->tv_tpg_mutex); + /* + * Release se_tpg->tpg_group.cg_item configfs dependency now + * to allow vhost-scsi WWPN se_tpg->tpg_group shutdown to occur. + */ + se_tpg = &tpg->se_tpg; + configfs_undepend_item(se_tpg->se_tpg_tfo->tf_subsys, + &se_tpg->tpg_group.cg_item); } if (match) { for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) { -- 2.7.4