From f2b7daf5b13f69ac09e706fb5b906478212a4100 Mon Sep 17 00:00:00 2001 From: Asias He Date: Thu, 25 Apr 2013 15:35:20 +0800 Subject: [PATCH] tcm_vhost: Refactor the lock nesting rule We want to use tcm_vhost_mutex to make sure hotplug/hotunplug will not happen when set_endpoint/clear_endpoint is in process. Signed-off-by: Asias He Acked-by: Michael S. Tsirkin Signed-off-by: Nicholas Bellinger --- drivers/vhost/tcm_vhost.c | 32 +++++++++++++++++++------------- 1 file changed, 19 insertions(+), 13 deletions(-) diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c index 957a0b98a5d9..822cd1fbff5e 100644 --- a/drivers/vhost/tcm_vhost.c +++ b/drivers/vhost/tcm_vhost.c @@ -808,6 +808,9 @@ static void vhost_scsi_flush(struct vhost_scsi *vs) /* * Called from vhost_scsi_ioctl() context to walk the list of available * tcm_vhost_tpg with an active struct tcm_vhost_nexus + * + * The lock nesting rule is: + * tcm_vhost_mutex -> vs->dev.mutex -> tpg->tv_tpg_mutex -> vq->mutex */ static int vhost_scsi_set_endpoint( struct vhost_scsi *vs, @@ -820,26 +823,27 @@ static int vhost_scsi_set_endpoint( int index, ret, i, len; bool match = false; + mutex_lock(&tcm_vhost_mutex); mutex_lock(&vs->dev.mutex); + /* Verify that ring has been setup correctly. */ for (index = 0; index < vs->dev.nvqs; ++index) { /* Verify that ring has been setup correctly. */ if (!vhost_vq_access_ok(&vs->vqs[index])) { - mutex_unlock(&vs->dev.mutex); - return -EFAULT; + ret = -EFAULT; + goto out; } } len = sizeof(vs_tpg[0]) * VHOST_SCSI_MAX_TARGET; vs_tpg = kzalloc(len, GFP_KERNEL); if (!vs_tpg) { - mutex_unlock(&vs->dev.mutex); - return -ENOMEM; + ret = -ENOMEM; + goto out; } if (vs->vs_tpg) memcpy(vs_tpg, vs->vs_tpg, len); - mutex_lock(&tcm_vhost_mutex); list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) { mutex_lock(&tv_tpg->tv_tpg_mutex); if (!tv_tpg->tpg_nexus) { @@ -854,11 +858,10 @@ static int vhost_scsi_set_endpoint( if (!strcmp(tv_tport->tport_name, t->vhost_wwpn)) { if (vs->vs_tpg && vs->vs_tpg[tv_tpg->tport_tpgt]) { - mutex_unlock(&tv_tpg->tv_tpg_mutex); - mutex_unlock(&tcm_vhost_mutex); - mutex_unlock(&vs->dev.mutex); kfree(vs_tpg); - return -EEXIST; + mutex_unlock(&tv_tpg->tv_tpg_mutex); + ret = -EEXIST; + goto out; } tv_tpg->tv_tpg_vhost_count++; vs_tpg[tv_tpg->tport_tpgt] = tv_tpg; @@ -867,7 +870,6 @@ static int vhost_scsi_set_endpoint( } mutex_unlock(&tv_tpg->tv_tpg_mutex); } - mutex_unlock(&tcm_vhost_mutex); if (match) { memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn, @@ -893,7 +895,9 @@ static int vhost_scsi_set_endpoint( kfree(vs->vs_tpg); vs->vs_tpg = vs_tpg; +out: mutex_unlock(&vs->dev.mutex); + mutex_unlock(&tcm_vhost_mutex); return ret; } @@ -908,6 +912,7 @@ static int vhost_scsi_clear_endpoint( int index, ret, i; u8 target; + mutex_lock(&tcm_vhost_mutex); mutex_lock(&vs->dev.mutex); /* Verify that ring has been setup correctly. */ for (index = 0; index < vs->dev.nvqs; ++index) { @@ -918,8 +923,8 @@ static int vhost_scsi_clear_endpoint( } if (!vs->vs_tpg) { - mutex_unlock(&vs->dev.mutex); - return 0; + ret = 0; + goto err_dev; } for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) { @@ -965,13 +970,14 @@ static int vhost_scsi_clear_endpoint( kfree(vs->vs_tpg); vs->vs_tpg = NULL; mutex_unlock(&vs->dev.mutex); - + mutex_unlock(&tcm_vhost_mutex); return 0; err_tpg: mutex_unlock(&tv_tpg->tv_tpg_mutex); err_dev: mutex_unlock(&vs->dev.mutex); + mutex_unlock(&tcm_vhost_mutex); return ret; }