Changeset d48fcc0 in mainline

Timestamp:

2011-04-09T09:45:14Z (13 years ago)

Author:

Vojtech Horky <vojtechhorky@…>

Branches:

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

Children:

e9ce696

Parents:

a546687

Message:

Fine grain locking of USB pipes

Location:

uspace/lib/usb

Files:

• include/usb/pipes.h (modified) (2 diffs)
• src/pipepriv.c (modified) (3 diffs)
• src/pipepriv.h (modified) (1 diff)
• src/pipesinit.c (modified) (1 diff)
• src/pipesio.c (modified) (14 diffs)

uspace/lib/usb/include/usb/pipes.h

@@ -60 +60 @@
  * This endpoint must be bound with existing usb_device_connection_t
  * (i.e. the wire to send data over).
+ *
+ * Locking order: if you want to lock both mutexes
+ * (@c guard and @c hc_phone_mutex), lock @c guard first.
+ * It is not necessary to lock @c guard if you want to lock @c hc_phone_mutex
+ * only.
  */
 typedef struct {
+        /** Guard of the whole pipe. */
+        fibril_mutex_t guard;
+
         /** The connection used for sending the data. */
         usb_device_connection_t *wire;
@@ -79 +87 @@
         /** Phone to the host controller.
          * Negative when no session is active.
+         * It is an error to access this member without @c hc_phone_mutex
+         * being locked.
+         * If call over the phone is to be made, it must be preceeded by
+         * call to pipe_add_ref() [internal libusb function].
          */
         int hc_phone;

uspace/lib/usb/src/pipepriv.c

@@ -42 +42 @@
  * @param pipe Pipe to be exclusively accessed.
  */
-void pipe_acquire(usb_pipe_t *pipe)
+void pipe_start_transaction(usb_pipe_t *pipe)
 {
         fibril_mutex_lock(&pipe->hc_phone_mutex);
@@ -51 +51 @@
  * @param pipe Pipe to be released from exclusive usage.
  */
+void pipe_end_transaction(usb_pipe_t *pipe)
+{
+        fibril_mutex_unlock(&pipe->hc_phone_mutex);
+}
+
+/** Ensure exclusive access to the pipe as a whole.
+ *
+ * @param pipe Pipe to be exclusively accessed.
+ */
+void pipe_acquire(usb_pipe_t *pipe)
+{
+        fibril_mutex_lock(&pipe->guard);
+}
+
+/** Terminate exclusive access to the pipe as a whole.
+ *
+ * @param pipe Pipe to be released from exclusive usage.
+ */
 void pipe_release(usb_pipe_t *pipe)
 {
-        fibril_mutex_unlock(&pipe->hc_phone_mutex);
+        fibril_mutex_unlock(&pipe->guard);
 }
 
@@ -76 +94 @@
                         goto another_try;
                 }
+                /*
+                 * No locking is needed, refcount is zero and whole pipe
+                 * mutex is locked.
+                 */
                 pipe->hc_phone = phone;
         }

uspace/lib/usb/src/pipepriv.h

@@ -41 +41 @@
 void pipe_release(usb_pipe_t *);
 
+void pipe_start_transaction(usb_pipe_t *);
+void pipe_end_transaction(usb_pipe_t *);
+
 int pipe_add_ref(usb_pipe_t *);
 void pipe_drop_ref(usb_pipe_t *);

uspace/lib/usb/src/pipesinit.c

@@ -356 +356 @@
         assert(connection);
 
+        fibril_mutex_initialize(&pipe->guard);
         pipe->wire = connection;
         pipe->hc_phone = -1;

uspace/lib/usb/src/pipesio.c

@@ -80 +80 @@
 
         /* Ensure serialization over the phone. */
-        pipe_acquire(pipe);
+        pipe_start_transaction(pipe);
 
         /*
@@ -91 +91 @@
             NULL);
         if (opening_request == 0) {
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
                 return ENOMEM;
         }
@@ -106 +106 @@
          * without breaking the transfer IPC protocol.
          */
-        pipe_release(pipe);
+        pipe_end_transaction(pipe);
 
         if (data_request == 0) {
@@ -227 +227 @@
 
         /* Ensure serialization over the phone. */
-        pipe_acquire(pipe);
+        pipe_start_transaction(pipe);
 
         /*
@@ -238 +238 @@
             NULL);
         if (opening_request == 0) {
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
                 return ENOMEM;
         }
@@ -251 +251 @@
          * without breaking the transfer IPC protocol.
          */
-        pipe_release(pipe);
+        pipe_end_transaction(pipe);
 
         if (rc != EOK) {
@@ -326 +326 @@
 {
         /* Ensure serialization over the phone. */
-        pipe_acquire(pipe);
+        pipe_start_transaction(pipe);
 
         /*
@@ -346 +346 @@
             setup_buffer, setup_buffer_size);
         if (rc != EOK) {
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
                 async_wait_for(opening_request, NULL);
                 return rc;
@@ -363 +363 @@
          * without breaking the transfer IPC protocol.
          */
-        pipe_release(pipe);
+        pipe_end_transaction(pipe);
 
 
@@ -468 +468 @@
 {
         /* Ensure serialization over the phone. */
-        pipe_acquire(pipe);
+        pipe_start_transaction(pipe);
 
         /*
@@ -480 +480 @@
             NULL);
         if (opening_request == 0) {
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
                 return ENOMEM;
         }
@@ -490 +490 @@
             setup_buffer, setup_buffer_size);
         if (rc != EOK) {
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
                 async_wait_for(opening_request, NULL);
                 return rc;
@@ -503 +503 @@
 
                 /* All data sent, pipe can be released. */
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
 
                 if (rc != EOK) {
@@ -511 +511 @@
         } else {
                 /* No data to send, we can release the pipe for others. */
-                pipe_release(pipe);
+                pipe_end_transaction(pipe);
         }