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, 2 insertions, 0 deletions

diff --git a/pfinet/glue-include/linux/interrupt.h b/pfinet/glue-include/linux/interrupt.h
index df58d2f4..22312ba4 100644
--- a/pfinet/glue-include/linux/interrupt.h
+++ b/pfinet/glue-include/linux/interrupt.h
@@ -21,6 +21,7 @@ extern pthread_mutex_t net_bh_lock;
 
 /* See sched.c::net_bh_worker comments.  */
 extern pthread_cond_t net_bh_wakeup;
+extern int net_bh_raised;
 
 #define NET_BH	0xb00bee51
 
@@ -30,6 +31,7 @@ static inline void
 mark_bh (int bh)
 {
   assert (bh == NET_BH);
+  net_bh_raised = 1;
   pthread_cond_broadcast (&net_bh_wakeup);
 }