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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 <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nicholas Bellinger 2015-01-30 22:17:22 +00:00 committed by Greg Kroah-Hartman
parent f2da3c240d
commit 3ce3a8612d
1 changed files with 24 additions and 0 deletions
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24
drivers/vhost/scsi.c
View File

@ -1150,6 +1150,7 @@ 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 *tv_tpg;
struct tcm_vhost_tpg **vs_tpg;
@ -1197,6 +1198,21 @@ static int vhost_scsi_set_endpoint(
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 = &tv_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(&tv_tpg->tv_tpg_mutex);
goto out;
}
tv_tpg->tv_tpg_vhost_count++;
tv_tpg->vhost_scsi = vs;
vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
@ -1240,6 +1256,7 @@ 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 *tv_tpg;
struct vhost_virtqueue *vq;
@ -1288,6 +1305,13 @@ static int vhost_scsi_clear_endpoint(
vs->vs_tpg[target] = NULL;
match = true;
mutex_unlock(&tv_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 = &tv_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++) {