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scst: Only free a device after all associated commands and LUNs have finished

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Merge scst_free_device() and scst_finally_free_device() into a single
function. Increase dev->refcnt when registering a device or virtual
device. Kill and decrease dev->refcnt when unregistering a device or
virtual device. These changes ensure that a scst_free_device() is
only called after all users (commands and tgt_devs) have stopped
accessing the SCST device.

Fixes: 3f2d50b589 ("scst: Do not suspend command processing when deleting a device"; r8067)



git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@8501 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2019-08-12 01:41:26 +00:00
parent 4e5548c409
commit c6e8013f48
4 changed files with 30 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
scst/include/scst.h
-2
View File
@@ -2894,8 +2894,6 @@ struct scst_device {
struct work_struct free_work;
struct completion *dev_freed_cmpl;
/*
* Maximum count of uncompleted commands that an initiator could
* queue on this device. Then it will start getting TASK QUEUE FULL
scst/src/scst_lib.c
+19 -38
View File
@@ -4185,20 +4185,33 @@ static int scst_dif_none_type1(struct scst_cmd *cmd);
#endif
/* Called from thread context and hence may sleep. */
static void scst_finally_free_device(struct work_struct *work)
static void scst_free_device(struct work_struct *work)
{
struct scst_device *dev = container_of(work, typeof(*dev),
free_work);
struct completion *c = dev->dev_freed_cmpl;
EXTRACHECKS_BUG_ON(dev->dev_scsi_atomic_cmd_active != 0);
EXTRACHECKS_BUG_ON(!list_empty(&dev->dev_exec_cmd_list));
#ifdef CONFIG_SCST_EXTRACHECKS
if (!list_empty(&dev->dev_tgt_dev_list) ||
!list_empty(&dev->dev_acg_dev_list)) {
PRINT_CRIT_ERROR("%s: dev_tgt_dev_list or dev_acg_dev_list "
"is not empty!", __func__);
sBUG();
}
#endif
/* Ensure that ext_blockers_work is done */
flush_work(&dev->ext_blockers_work);
scst_deinit_threads(&dev->dev_cmd_threads);
scst_pr_cleanup(dev);
kfree(dev->virt_name);
percpu_ref_exit(&dev->refcnt);
kmem_cache_free(scst_dev_cachep, dev);
if (c)
complete(c);
}
/* RCU callback. Must not sleep. */
@@ -4227,7 +4240,7 @@ int scst_alloc_device(gfp_t gfp_mask, int nodeid, struct scst_device **out_dev)
memset(dev, 0, sizeof(*dev));
dev->handler = &scst_null_devtype;
INIT_WORK(&dev->free_work, scst_finally_free_device);
INIT_WORK(&dev->free_work, scst_free_device);
res = percpu_ref_init(&dev->refcnt, scst_release_device, 0, GFP_KERNEL);
if (res < 0)
goto free_dev;
@@ -4272,38 +4285,6 @@ free_dev:
goto out;
}
void scst_free_device(struct scst_device *dev)
{
DECLARE_COMPLETION_ONSTACK(c);
TRACE_ENTRY();
EXTRACHECKS_BUG_ON(dev->dev_scsi_atomic_cmd_active != 0);
EXTRACHECKS_BUG_ON(!list_empty(&dev->dev_exec_cmd_list));
#ifdef CONFIG_SCST_EXTRACHECKS
if (!list_empty(&dev->dev_tgt_dev_list) ||
!list_empty(&dev->dev_acg_dev_list)) {
PRINT_CRIT_ERROR("%s: dev_tgt_dev_list or dev_acg_dev_list "
"is not empty!", __func__);
sBUG();
}
#endif
/* Ensure that ext_blockers_work is done */
flush_work(&dev->ext_blockers_work);
scst_deinit_threads(&dev->dev_cmd_threads);
dev->dev_freed_cmpl = &c;
percpu_ref_kill(&dev->refcnt);
wait_for_completion(&c);
TRACE_EXIT();
return;
}
bool scst_device_is_exported(struct scst_device *dev)
{
lockdep_assert_held(&scst_mutex);
scst/src/scst_main.c
+11 -5
View File
@@ -1132,6 +1132,8 @@ static int scst_register_device(struct scsi_device *scsidp)
if (res != 0)
goto out_del_unlocked;
percpu_ref_get(&dev->refcnt);
PRINT_INFO("Attached to scsi%d, channel %d, id %d, lun %lld, type %d",
scsidp->host->host_no, scsidp->channel, scsidp->id,
(u64)scsidp->lun, scsidp->type);
@@ -1145,7 +1147,7 @@ out_del_unlocked:
list_del_init(&dev->dev_list_entry);
mutex_unlock(&scst_mutex);
scst_free_device(dev);
percpu_ref_kill(&dev->refcnt);
goto out;
#ifdef CONFIG_SCST_FORWARD_MODE_PASS_THROUGH
@@ -1153,7 +1155,7 @@ out_del_unlocked:
#endif
out_free_dev:
scst_free_device(dev);
percpu_ref_kill(&dev->refcnt);
out_unlock:
mutex_unlock(&scst_mutex);
@@ -1213,7 +1215,8 @@ static void scst_unregister_device(struct scsi_device *scsidp)
scsidp->host->host_no, scsidp->channel, scsidp->id,
(u64)scsidp->lun, scsidp->type);
scst_free_device(dev);
percpu_ref_kill(&dev->refcnt);
percpu_ref_put(&dev->refcnt);
out:
TRACE_EXIT();
@@ -1393,6 +1396,8 @@ int scst_register_virtual_device_node(struct scst_dev_type *dev_handler,
mutex_unlock(&scst_mutex);
percpu_ref_get(&dev->refcnt);
res = dev->virt_id;
PRINT_INFO("Attached to virtual device %s (id %d)", dev_name, res);
@@ -1416,7 +1421,7 @@ out_free_dev:
mutex_unlock(&scst_mutex);
if (sysfs_del)
scst_dev_sysfs_del(dev);
scst_free_device(dev);
percpu_ref_kill(&dev->refcnt);
goto out;
out_unlock:
@@ -1478,7 +1483,8 @@ void scst_unregister_virtual_device(int id,
if (on_free)
on_free(dev, arg);
scst_free_device(dev);
percpu_ref_kill(&dev->refcnt);
percpu_ref_put(&dev->refcnt);
out:
TRACE_EXIT();
scst/src/scst_priv.h
-1
View File
@@ -365,7 +365,6 @@ int scst_alloc_tgt(struct scst_tgt_template *tgtt, struct scst_tgt **tgt);
void scst_free_tgt(struct scst_tgt *tgt);
int scst_alloc_device(gfp_t gfp_mask, int nodeid, struct scst_device **out_dev);
void scst_free_device(struct scst_device *dev);
bool scst_device_is_exported(struct scst_device *dev);
int scst_alloc_add_acg(struct scst_tgt *tgt, const char *acg_name,