Changeset f527f58 in mainline

Timestamp:

2016-08-03T11:12:24Z (9 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

96ef672

Parents:

e657635

Message:

Reference-count endpoint_t structures

Track explicit references to USB endpoints. Call endpoint_destroy()
only after the last reference is destroyed. This prevents the scenario
in which removal was attempted on an endpoint while there was a transfer
in progress.

Location:

uspace/lib/usbhost

Files:

• include/usb/host/endpoint.h (modified) (2 diffs)
• src/endpoint.c (modified) (7 diffs)
• src/hcd.c (modified) (1 diff)
• src/usb_bus.c (modified) (6 diffs)

uspace/lib/usbhost/include/usb/host/endpoint.h

@@ -40 +40 @@
 #include <fibril_synch.h>
 #include <usb/usb.h>
+#include <atomic.h>
 
 /** Host controller side endpoint structure. */
 typedef struct endpoint {
+        /** Reference count. */
+        atomic_t refcnt;        
         /** Part of linked list. */
         link_t link;
@@ -91 +94 @@
 void endpoint_destroy(endpoint_t *instance);
 
+void endpoint_add_ref(endpoint_t *instance);
+void endpoint_del_ref(endpoint_t *instance);
+
 void endpoint_set_hc_data(endpoint_t *instance,
     void *data, int (*toggle_get)(void *), void (*toggle_set)(void *, int));

uspace/lib/usbhost/src/endpoint.c

@@ -26 +26 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+
 /** @addtogroup libusbhost
  * @{
@@ -37 +38 @@
 #include <assert.h>
 #include <stdlib.h>
+#include <atomic.h>
 
 /** Allocate ad initialize endpoint_t structure.
@@ -55 +57 @@
         endpoint_t *instance = malloc(sizeof(endpoint_t));
         if (instance) {
+                atomic_set(&instance->refcnt, 0);
                 instance->address = address;
                 instance->endpoint = endpoint;
@@ -83 +86 @@
 {
         assert(instance);
-        //TODO: Do something about waiting fibrils.
         assert(!instance->active);
         assert(instance->hc_data.data == NULL);
         free(instance);
+}
+
+void endpoint_add_ref(endpoint_t *instance)
+{
+        atomic_inc(&instance->refcnt);
+}
+
+void endpoint_del_ref(endpoint_t *instance)
+{
+        if (atomic_predec(&instance->refcnt) == 0)
+                endpoint_destroy(instance);
 }
 
@@ -122 +135 @@
 {
         assert(instance);
+        /* Add reference for active endpoint. */
+        endpoint_add_ref(instance);
         fibril_mutex_lock(&instance->guard);
         while (instance->active)
@@ -139 +154 @@
         fibril_mutex_unlock(&instance->guard);
         fibril_condvar_signal(&instance->avail);
+        /* Drop reference for active endpoint. */
+        endpoint_del_ref(instance);
 }
 
@@ -171 +188 @@
         fibril_mutex_unlock(&instance->guard);
 }
+
 /**
  * @}

uspace/lib/usbhost/src/hcd.c

@@ -241 +241 @@
                 usb_transfer_batch_destroy(batch);
 
+        /* Drop our own reference to ep. */
+        endpoint_del_ref(ep);
+
         return ret;
 }

uspace/lib/usbhost/src/usb_bus.c

@@ -242 +242 @@
                 return EEXIST;
         }
+        /* Add endpoint list's reference to ep. */
+        endpoint_add_ref(ep);
         list_append(&ep->link, get_list(instance, ep->address));
 
@@ -274 +276 @@
             ep->endpoint, usb_str_transfer_type_short(ep->transfer_type),
             usb_str_direction(ep->direction));
+        /* Drop endpoint list's reference to ep. */
+        endpoint_del_ref(ep);
         fibril_mutex_unlock(&instance->guard);
         return EOK;
@@ -289 +293 @@
         fibril_mutex_lock(&instance->guard);
         endpoint_t *ep = find_locked(instance, address, endpoint, direction);
+        if (ep) {
+                /* We are exporting ep to the outside world, add reference. */
+                endpoint_add_ref(ep);
+        }
         fibril_mutex_unlock(&instance->guard);
         return ep;
@@ -350 +358 @@
         }
 
+        /* Add our reference to ep. */
+        endpoint_add_ref(ep);
+
         if (callback) {
                 const int ret = callback(ep, arg);
                 if (ret != EOK) {
                         fibril_mutex_unlock(&instance->guard);
-                        endpoint_destroy(ep);
+                        endpoint_del_ref(ep);
                         return ret;
                 }
         }
+        
+        /* Add endpoint list's reference to ep. */
+        endpoint_add_ref(ep);
         list_append(&ep->link, get_list(instance, ep->address));
 
         instance->free_bw -= ep->bandwidth;
         fibril_mutex_unlock(&instance->guard);
+
+        /* Drop our reference to ep. */
+        endpoint_del_ref(ep);
+
         return EOK;
 }
@@ -392 +410 @@
                 callback(ep, arg);
         }
-        endpoint_destroy(ep);
+        /* Drop endpoint list's reference to ep. */
+        endpoint_del_ref(ep);
         return EOK;
 }
@@ -445 +464 @@
                         if (callback)
                                 callback(ep, arg);
-                        endpoint_destroy(ep);
+                        /* Drop endpoint list's reference to ep. */
+                        endpoint_del_ref(ep);
                 }
         }