pin
diff --git a/src/lib9/mkfile b/src/lib9/mkfile
index 143ca7d..ca61543 100644
--- a/src/lib9/mkfile
+++ b/src/lib9/mkfile
@@ -128,6 +128,7 @@
nulldir.$O\
open.$O\
opentemp.$O\
+ pin.$O\
pipe.$O\
post9p.$O\
postnote.$O\
diff --git a/src/lib9/pin.c b/src/lib9/pin.c
new file mode 100644
index 0000000..3b15d3b
--- /dev/null
+++ b/src/lib9/pin.c
@@ -0,0 +1,11 @@
+#include <u.h>
+#include <libc.h>
+
+static void
+nop(void)
+{
+}
+
+void (*_pin)(void) = nop;
+void (*_unpin)(void) = nop;
+
diff --git a/src/libthread/thread.c b/src/libthread/thread.c
index acd56fa..48dd3e1 100644
--- a/src/libthread/thread.c
+++ b/src/libthread/thread.c
@@ -12,6 +12,7 @@
static void delproc(Proc*);
static void addthread(_Threadlist*, _Thread*);
static void delthread(_Threadlist*, _Thread*);
+static int onlist(_Threadlist*, _Thread*);
static void addthreadinproc(Proc*, _Thread*);
static void delthreadinproc(Proc*, _Thread*);
static void contextswitch(Context *from, Context *to);
@@ -254,6 +255,32 @@
_threadswitch();
}
+void
+threadpin(void)
+{
+ Proc *p;
+
+ p = proc();
+ if(p->pinthread){
+ fprint(2, "already pinning a thread - %p %p\n", p->pinthread, p->thread);
+ assert(0);
+ }
+ p->pinthread = p->thread;
+}
+
+void
+threadunpin(void)
+{
+ Proc *p;
+
+ p = proc();
+ if(p->pinthread != p->thread){
+ fprint(2, "wrong pinthread - %p %p\n", p->pinthread, p->thread);
+ assert(0);
+ }
+ p->pinthread = nil;
+}
+
static void
contextswitch(Context *from, Context *to)
{
@@ -273,6 +300,14 @@
/* print("s %p\n", p); */
lock(&p->lock);
for(;;){
+ if((t = p->pinthread) != nil){
+ while(!onlist(&p->runqueue, t)){
+ p->runrend.l = &p->lock;
+ _threaddebug("scheduler sleep (pin)");
+ _procsleep(&p->runrend);
+ _threaddebug("scheduler wake (pin)");
+ }
+ }else
while((t = p->runqueue.head) == nil){
if(p->nthread == 0)
goto Out;
@@ -291,6 +326,9 @@
_procsleep(&p->runrend);
_threaddebug("scheduler wake");
}
+ if(p->pinthread && p->pinthread != t)
+ fprint(2, "p->pinthread %p t %p\n", p->pinthread, t);
+ assert(p->pinthread == nil || p->pinthread == t);
delthread(&p->runqueue, t);
unlock(&p->lock);
p->thread = t;
@@ -652,6 +690,8 @@
_rsleep = threadrsleep;
_rwakeup = threadrwakeup;
_notejmpbuf = threadnotejmp;
+ _pin = threadpin;
+ _unpin = threadunpin;
_pthreadinit();
p = procalloc();
@@ -697,6 +737,18 @@
l->tail = t->prev;
}
+/* inefficient but rarely used */
+static int
+onlist(_Threadlist *l, _Thread *t)
+{
+ _Thread *tt;
+
+ for(tt = l->head; tt; tt=tt->next)
+ if(tt == t)
+ return 1;
+ return 0;
+}
+
static void
addthreadinproc(Proc *p, _Thread *t)
{
