Rework/comment on the userspace interrupt handling

3 files changed, 35 insertions, 24 deletions

diff --git a/device/ds_routines.c b/device/ds_routines.c
index 9d399ee..7a5dda5 100644
--- a/device/ds_routines.c
+++ b/device/ds_routines.c
@@ -325,9 +325,7 @@ experimental_device_intr_register (ipc_port_t master_port, int line,
 #ifdef MACH_XEN
   return D_INVALID_OPERATION;
 #else	/* MACH_XEN */
-  extern int install_user_intr_handler (unsigned int line,
-					unsigned long flags,
-					ipc_port_t dest);
+  struct intr_entry *entry;
   io_return_t ret;
 
   /* Open must be called on the master device port.  */
@@ -338,13 +336,13 @@ experimental_device_intr_register (ipc_port_t master_port, int line,
   if (line < 0 || line >= 16)
     return D_INVALID_OPERATION;
 
-  ret = insert_intr_entry (line, receive_port);
+  ret = insert_intr_entry (line, receive_port, &entry);
   if (ret)
     return ret;
   // TODO The original port should be replaced
   // when the same device driver calls it again, 
   // in order to handle the case that the device driver crashes and restarts.
-  ret = install_user_intr_handler (line, flags, receive_port);
+  ret = install_user_intr_handler (line, flags, entry);
 
   /* If the port is installed successfully, increase its reference by 1.
    * Thus, the port won't be destroyed after its task is terminated. */
diff --git a/device/interrupt.h b/device/interrupt.h
new file mode 100644
index 0000000..0de43c2
--- /dev/null
+++ b/device/interrupt.h
@@ -0,0 +1,14 @@
+#ifndef DEVICE_INTERRUPT_H
+#define DEVICE_INTERRUPT_H
+
+struct intr_entry;
+boolean_t queue_intr (struct intr_entry *e);
+int insert_intr_entry (int line, ipc_port_t dest, struct intr_entry **entry);
+
+int install_user_intr_handler (unsigned int line,
+			       unsigned long flags,
+			       struct intr_entry *entry);
+
+void intr_thread (void);
+
+#endif	/* DEVICE_INTERRUPT_H */
diff --git a/device/intr.c b/device/intr.c
index 02e0bab..986f0ee 100644
--- a/device/intr.c
+++ b/device/intr.c
@@ -3,6 +3,8 @@
 #include <kern/queue.h>
 #include <kern/printf.h>
 
+#include "interrupt.h"
+
 #ifndef MACH_XEN
 // TODO this is only for x86 system
 #define sti() __asm__ __volatile__ ("sti": : :"memory")
@@ -35,29 +37,35 @@ search_intr (int line, ipc_port_t dest)
   return NULL;
 }
 
-void intr_thread (void);
-
 /* This function can only be used in the interrupt handler. */
-void
-queue_intr (int line, ipc_port_t dest)
+boolean_t
+queue_intr (struct intr_entry *e)
 {
-  struct intr_entry *e;
-  
+  /* The reference of the port was increased when the port was
+   * installed.  If the reference is 1, it means the port should have
+   * been destroyed and I destroy it now. */
+  if (e->dest && e->dest->ip_references == 1)
+    {
+      ipc_port_release (e->dest);
+      e->dest = NULL;
+      printk ("irq handler %d: release an dead delivery port\n", e->line);
+      return FALSE;
+    }
+
   cli ();
-  e = search_intr (line, dest);
-  assert (e);
   e->interrupts++;
   tot_num_intr++;
   sti ();
 
   thread_wakeup ((event_t) &intr_thread);
+  return TRUE;
 }
 
 /* insert an interrupt entry in the queue.
  * This entry exists in the queue until
  * the corresponding interrupt port is removed.*/
 int
-insert_intr_entry (int line, ipc_port_t dest)
+insert_intr_entry (int line, ipc_port_t dest, struct intr_entry **entry)
 {
   int err = 0;
   struct intr_entry *e, *new;
@@ -86,19 +94,10 @@ out:
   sti ();
   if (free)
     kfree ((vm_offset_t) new, sizeof (*new));
+  *entry = new;
   return err;
 }
 
-/* this function should be called when line is disabled. */
-void mark_intr_removed (int line, ipc_port_t dest)
-{
-  struct intr_entry *e;
-
-  e = search_intr (line, dest);
-  if (e)
-    e->dest = NULL;
-}
-
 void
 intr_thread ()
 {