pfinet: fix emission on the loopback device

Unlike other devices, sending packets on the loopback device causes the
netif_rx() function to be called from the net_bh worker thread. Since
the thread is already running, it can't wake itself up when calling
mark_bh(). Use a new variable to indicate when net_bh work is pending.

* glue-include/linux/interrupt.h (net_bh_raised): Declare new global
variable.
(mark_bh): Set net_bh_raised to 1 before waking up net_bh worker thread.
* loopback.c (loopback_xmit): Add comment giving details about locking.
* sched.c (net_bh_raised): Define new global variable.
(net_bh_worker): Wait for net_bh_raised to become true and reset it
before processing net_bh work.

1 files changed, 6 insertions, 1 deletions

diff --git a/pfinet/sched.c b/pfinet/sched.c
index 89927741..af03ab49 100644
--- a/pfinet/sched.c
+++ b/pfinet/sched.c
@@ -26,6 +26,7 @@
 pthread_mutex_t global_lock = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutex_t net_bh_lock = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t net_bh_wakeup = PTHREAD_COND_INITIALIZER;
+int net_bh_raised = 0;
 
 struct task_struct current_contents; /* zeros are right default values */
 
@@ -61,7 +62,11 @@ net_bh_worker (void *arg)
   pthread_mutex_lock (&net_bh_lock);
   while (1)
     {
-      pthread_cond_wait (&net_bh_wakeup, &net_bh_lock);
+      while (!net_bh_raised)
+        pthread_cond_wait (&net_bh_wakeup, &net_bh_lock);
+
+      net_bh_raised = 0;
+
       pthread_mutex_lock (&global_lock);
       net_bh ();
       pthread_mutex_unlock (&global_lock);