sergiotarxz/nuttx
sergiotarxz/nuttx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix possibly deadlock condition

Browse Source 
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3601 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2011-05-13 03:33:03 +00:00
parent 3e1e4f6876
commit 1c99e6b36b
1 changed files with 21 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
drivers/usbhost/usbhost_storage.c
View File

@ -937,10 +937,6 @@ static void usbhost_destroy(FAR void *arg)
* On success, zero (OK) is returned. On a failure, a negated errno value is * On success, zero (OK) is returned. On a failure, a negated errno value is
* returned indicating the nature of the failure * returned indicating the nature of the failure
* *
* NOTE that the class instance remains valid upon return with a failure. It is
* the responsibility of the higher level enumeration logic to call
* CLASS_DISCONNECTED to free up the class driver resources.
*
* Assumptions: * Assumptions:
* This function will *not* be called from an interrupt handler. * This function will *not* be called from an interrupt handler.
* *
@ -1288,28 +1284,33 @@ static inline int usbhost_initvolume(FAR struct usbhost_state_s *priv)
usbhost_takesem(&priv->exclsem); usbhost_takesem(&priv->exclsem);
DEBUGASSERT(priv->crefs >= 2); DEBUGASSERT(priv->crefs >= 2);
/* Decrement the reference count */
priv->crefs--;
/* Handle a corner case where (1) open() has been called so the /* Handle a corner case where (1) open() has been called so the
* reference count is > 2, but the device has been disconnected. * reference count was > 2, but the device has been disconnected.
* In this case, the class instance needs to persist until close() * In this case, the class instance needs to persist until close()
* is called. * is called.
*/ */
if (priv->crefs <= 2 && priv->disconnected) if (priv->crefs <= 1 && priv->disconnected)
{ {
/* We don't have to give the semaphore because it will be /* The will cause the enumeration logic to disconnect
* destroyed when usb_destroy is called. * the class driver.
*/ */
ret = -ENODEV; ret = -ENODEV;
} }
else
{
/* Ready for normal operation as a block device driver */
uvdbg("Successfully initialized\n"); /* Release the semaphore... there is a race condition here.
priv->crefs--; * Decrementing the reference count and releasing the semaphore
usbhost_givesem(&priv->exclsem); * allows usbhost_destroy() to execute (on the worker thread);
} * the class driver instance could get destoryed before we are
* ready to handle it!
*/
usbhost_givesem(&priv->exclsem);
} }
return ret; return ret;
@ -1671,6 +1672,10 @@ static FAR struct usbhost_class_s *usbhost_create(FAR struct usbhost_driver_s *d
* On success, zero (OK) is returned. On a failure, a negated errno value is * On success, zero (OK) is returned. On a failure, a negated errno value is
* returned indicating the nature of the failure * returned indicating the nature of the failure
* *
* NOTE that the class instance remains valid upon return with a failure. It is
* the responsibility of the higher level enumeration logic to call
* CLASS_DISCONNECTED to free up the class driver resources.
*
* Assumptions: * Assumptions:
* - This function will *not* be called from an interrupt handler. * - This function will *not* be called from an interrupt handler.
* - If this function returns an error, the USB host controller driver * - If this function returns an error, the USB host controller driver