Condvar: Add some tracepoints

core/condvar.cc

 #include <osv/condvar.h>
 #include <sched.h>
 #include <errno.h>
+#include <osv/trace.hh>
 #include <osv/wait_record.hh>
 
+TRACEPOINT(trace_condvar_wait, "%p", condvar *);
+TRACEPOINT(trace_condvar_wake_one, "%p", condvar *);
+TRACEPOINT(trace_condvar_wake_all, "%p", condvar *);
+
 int condvar_wait(condvar_t *condvar, mutex_t* user_mutex, uint64_t expiration)
 {
     if (expiration) {
@@ -16,6 +21,7 @@ int condvar_wait(condvar_t *condvar, mutex_t* user_mutex, uint64_t expiration)
 
 int condvar_wait(condvar_t *condvar, mutex_t* user_mutex, sched::timer* tmr)
 {
+    trace_condvar_wait(condvar);
     int ret = 0;
     wait_record wr(sched::thread::current());
 
@@ -74,6 +80,7 @@ int condvar_wait(condvar_t *condvar, mutex_t* user_mutex, sched::timer* tmr)
 
 void condvar_wake_one(condvar_t *condvar)
 {
+    trace_condvar_wake_one(condvar);
     // To make wake with no waiters faster, and avoid unnecessary contention
     // in that case, first check the queue head outside the lock. If it is not
     // empty, we still need to take the lock, and re-read the head.
@@ -103,6 +110,7 @@ void condvar_wake_one(condvar_t *condvar)
 
 void condvar_wake_all(condvar_t *condvar)
 {
+    trace_condvar_wake_all(condvar);
     if (!condvar->waiters_fifo.oldest) {
         return;
     }