tlibthread: run first thread in proc on system stack - plan9port - [fork] Plan 9 from user space
(HTM) git clone git://src.adamsgaard.dk/plan9port
(DIR) Log
(DIR) Files
(DIR) Refs
(DIR) README
(DIR) LICENSE
---
(DIR) commit 0158bceec78c7891a7ef672770bf42e65fd064dd
(DIR) parent e0c4896ed41faa71445d9e0b1751aba5157343c9
(HTM) Author: Russ Cox <rsc@swtch.com>
Date: Wed, 8 Jan 2020 22:47:51 -0500
libthread: run first thread in proc on system stack
For pthread systems that are fussy about which stack is used,
tthis makes sure that threadmain runs on a system stack.
If you only use proccreate (never threadcreate), all threads run
on system stacks.
Diffstat:
M man/man3/thread.3 | 8 ++++++++
M src/libthread/test/tspawnloop.c | 4 ++--
M src/libthread/thread.c | 59 +++++++++++++++++++++++--------
M src/libthread/threadimpl.h | 1 -
4 files changed, 55 insertions(+), 17 deletions(-)
---
(DIR) diff --git a/man/man3/thread.3 b/man/man3/thread.3
t@@ -169,6 +169,14 @@ initialized to the desired value
.B mainstacksize
.B =
.BR 1024 ).
+When using the
+.I pthread
+library,
+.B mainstacksize
+is ignored, as is the stack size argument to
+.BR proccreate :
+the first thread in each proc
+runs on the native system stack.
.PP
.I Threadcreate
creates a new thread in the calling proc, returning a unique integer
(DIR) diff --git a/src/libthread/test/tspawnloop.c b/src/libthread/test/tspawnloop.c
t@@ -8,7 +8,7 @@ execproc(void *v)
int i, fd[3];
char buf[100], *args[3];
- i = (int)v;
+ i = (int)(uintptr)v;
sprint(buf, "%d", i);
fd[0] = dup(0, -1);
fd[1] = dup(1, -1);
t@@ -33,7 +33,7 @@ threadmain(int argc, char **argv)
c = threadwaitchan();
for(i=0;; i++){
- proccreate(execproc, (void*)i, 16384);
+ proccreate(execproc, (void*)(uintptr)i, 16384);
w = recvp(c);
if(w == nil)
sysfatal("exec/recvp failed: %r");
(DIR) diff --git a/src/libthread/thread.c b/src/libthread/thread.c
t@@ -16,6 +16,7 @@ static int onlist(_Threadlist*, _Thread*);
static void addthreadinproc(Proc*, _Thread*);
static void delthreadinproc(Proc*, _Thread*);
static void contextswitch(Context *from, Context *to);
+static void procmain(Proc*);
static void procscheduler(Proc*);
static int threadinfo(void*, char*);
t@@ -112,8 +113,6 @@ threadalloc(void (*fn)(void*), void *arg, uint stack)
if(t == nil)
sysfatal("threadalloc malloc: %r");
memset(t, 0, sizeof *t);
- t->stk = (uchar*)(t+1);
- t->stksize = stack;
t->id = incref(&threadidref);
//print("fn=%p arg=%p\n", fn, arg);
t->startfn = fn;
t@@ -121,6 +120,10 @@ threadalloc(void (*fn)(void*), void *arg, uint stack)
//print("makecontext sp=%p t=%p startfn=%p\n", (char*)t->stk+t->stksize, t, t->startfn);
/* do a reasonable initialization */
+ if(stack == 0)
+ return t;
+ t->stk = (uchar*)(t+1);
+ t->stksize = stack;
memset(&t->context.uc, 0, sizeof t->context.uc);
sigemptyset(&zero);
sigprocmask(SIG_BLOCK, &zero, &t->context.uc.uc_sigmask);
t@@ -165,6 +168,8 @@ _threadcreate(Proc *p, void (*fn)(void*), void *arg, uint stack)
if(stack < (256<<10))
stack = 256<<10;
+ if(p->nthread == 0)
+ stack = 0; // not using it
t = threadalloc(fn, arg, stack);
t->proc = p;
addthreadinproc(p, t);
t@@ -192,7 +197,7 @@ proccreate(void (*fn)(void*), void *arg, uint stack)
p = procalloc();
t = _threadcreate(p, fn, arg, stack);
id = t->id; /* t might be freed after _procstart */
- _procstart(p, procscheduler);
+ _procstart(p, procmain);
return id;
}
t@@ -204,7 +209,10 @@ _threadswitch(void)
needstack(0);
p = proc();
/*print("threadswtch %p\n", p); */
- contextswitch(&p->thread->context, &p->schedcontext);
+ if(p->thread->stk == nil)
+ procscheduler(p);
+ else
+ contextswitch(&p->thread->context, &p->schedcontext);
}
void
t@@ -312,14 +320,42 @@ contextswitch(Context *from, Context *to)
}
static void
+procmain(Proc *p)
+{
+ _Thread *t;
+
+ _threadsetproc(p);
+
+ /* take out first thread to run on system stack */
+ t = p->runqueue.head;
+ delthread(&p->runqueue, t);
+ memset(&t->context.uc, 0, sizeof t->context.uc);
+
+ /* run it */
+ p->thread = t;
+ t->startfn(t->startarg);
+ if(p->nthread != 0)
+ threadexits(nil);
+}
+
+static void
procscheduler(Proc *p)
{
_Thread *t;
- setproc(p);
_threaddebug("scheduler enter");
//print("s %p\n", p);
+Top:
lock(&p->lock);
+ t = p->thread;
+ p->thread = nil;
+ if(t->exiting){
+ delthreadinproc(p, t);
+ p->nthread--;
+/*print("nthread %d\n", p->nthread); */
+ free(t);
+ }
+
for(;;){
if((t = p->pinthread) != nil){
while(!onlist(&p->runqueue, t)){
t@@ -356,16 +392,11 @@ procscheduler(Proc *p)
p->nswitch++;
_threaddebug("run %d (%s)", t->id, t->name);
//print("run %p %p %p %p\n", t, *(uintptr*)(t->context.uc.mc.sp), t->context.uc.mc.di, t->context.uc.mc.si);
+ if(t->stk == nil)
+ return;
contextswitch(&p->schedcontext, &t->context);
/*print("back in scheduler\n"); */
- p->thread = nil;
- lock(&p->lock);
- if(t->exiting){
- delthreadinproc(p, t);
- p->nthread--;
-/*print("nthread %d\n", p->nthread); */
- free(t);
- }
+ goto Top;
}
Out:
t@@ -749,7 +780,7 @@ main(int argc, char **argv)
mainstacksize = 256*1024;
atnotify(threadinfo, 1);
_threadcreate(p, threadmainstart, nil, mainstacksize);
- procscheduler(p);
+ procmain(p);
sysfatal("procscheduler returned in threadmain!");
/* does not return */
return 0;
(DIR) diff --git a/src/libthread/threadimpl.h b/src/libthread/threadimpl.h
t@@ -187,7 +187,6 @@ struct Proc
};
#define proc() _threadproc()
-#define setproc(p) _threadsetproc(p)
extern Proc *_threadprocs;
extern Lock _threadprocslock;