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Merge of r972 and r977:

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- Fixes a race, which can lead to a hang, if a user space handler with >1 devices gets killed under load

 - Fix double free



git-svn-id: http://svn.code.sf.net/p/scst/svn/branches/1.0.1.x@978 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Vladislav Bolkhovitin
2009-07-27 16:46:00 +00:00
parent de285c9c59
commit 5625a82c8a
1 changed files with 59 additions and 22 deletions
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81
scst/src/dev_handlers/scst_user.c
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@@ -196,6 +196,7 @@ static unsigned int dev_user_poll(struct file *filp, poll_table *wait);
static long dev_user_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
static int dev_user_release(struct inode *inode, struct file *file);
static int dev_user_exit_dev(struct scst_user_dev *dev);
static int dev_user_read_proc(struct seq_file *seq,
struct scst_dev_type *dev_type);
@@ -2819,7 +2820,25 @@ static int dev_user_unregister_dev(struct file *file)
up_read(&dev->dev_rwsem);
dev_user_release(NULL, file);
mutex_lock(&dev_priv_mutex);
dev = (struct scst_user_dev *)file->private_data;
if (dev == NULL) {
mutex_unlock(&dev_priv_mutex);
goto out;
}
dev->blocking = 0;
wake_up_all(&dev->cmd_lists.cmd_list_waitQ);
down_write(&dev->dev_rwsem);
file->private_data = NULL;
mutex_unlock(&dev_priv_mutex);
dev_user_exit_dev(dev);
up_write(&dev->dev_rwsem); /* to make lockdep happy */
kfree(dev);
scst_resume_activity();
@@ -3051,21 +3070,10 @@ static int dev_usr_parse(struct scst_cmd *cmd)
static struct scst_dev_type dev_user_devtype = USR_TYPE;
static int dev_user_release(struct inode *inode, struct file *file)
static int dev_user_exit_dev(struct scst_user_dev *dev)
{
int res = 0;
struct scst_user_dev *dev;
TRACE_ENTRY();
mutex_lock(&dev_priv_mutex);
dev = (struct scst_user_dev *)file->private_data;
if (dev == NULL) {
mutex_unlock(&dev_priv_mutex);
goto out;
}
file->private_data = NULL;
TRACE(TRACE_MGMT, "Releasing dev %s", dev->name);
spin_lock(&dev_list_lock);
@@ -3075,9 +3083,6 @@ static int dev_user_release(struct inode *inode, struct file *file)
dev->blocking = 0;
wake_up_all(&dev->cmd_lists.cmd_list_waitQ);
down_write(&dev->dev_rwsem);
mutex_unlock(&dev_priv_mutex);
spin_lock(&cleanup_lock);
list_add_tail(&dev->cleanup_list_entry, &cleanup_list);
spin_unlock(&cleanup_lock);
@@ -3102,17 +3107,49 @@ static int dev_user_release(struct inode *inode, struct file *file)
sgv_pool_destroy(dev->pool_clust);
sgv_pool_destroy(dev->pool);
up_write(&dev->dev_rwsem); /* to make lockdep happy */
TRACE_MGMT_DBG("Releasing completed (dev %p)", dev);
kfree(dev);
module_put(THIS_MODULE);
TRACE_EXIT();
return 0;
}
static int __dev_user_release(void *arg)
{
struct scst_user_dev *dev = (struct scst_user_dev *)arg;
dev_user_exit_dev(dev);
kfree(dev);
return 0;
}
static int dev_user_release(struct inode *inode, struct file *file)
{
struct scst_user_dev *dev;
struct task_struct *t;
TRACE_ENTRY();
dev = (struct scst_user_dev *)file->private_data;
if (dev == NULL) {
mutex_unlock(&dev_priv_mutex);
goto out;
}
file->private_data = NULL;
TRACE_MGMT_DBG("Going to release dev %s", dev->name);
t = kthread_run(__dev_user_release, dev, "scst_usr_released");
if (IS_ERR(t)) {
PRINT_CRIT_ERROR("kthread_run() failed (%ld), releasing device "
"%p directly. If you have several devices under load "
"it might deadlock!", PTR_ERR(t), dev);
__dev_user_release(dev);
}
out:
TRACE_EXIT_RES(res);
return res;
TRACE_EXIT();
return 0;
}
static int dev_user_process_cleanup(struct scst_user_dev *dev)