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authorRob Pike <r@golang.org>2009-06-09 09:53:44 -0700
committerRob Pike <r@golang.org>2009-06-09 09:53:44 -0700
commit7249ea4df2b4f12a4e7ed446f270cea87e4ffd34 (patch)
tree7032a11d0cac2ae4d3e90f7a189b575b5a50f848 /src/lib/runtime/linux/thread.c
parentacf6ef7a82b3fe61516a1bac4563706552bdf078 (diff)
downloadgolang-7249ea4df2b4f12a4e7ed446f270cea87e4ffd34.tar.gz
mv src/lib to src/pkg
tests: all.bash passes, gobuild still works, godoc still works. R=rsc OCL=30096 CL=30102
Diffstat (limited to 'src/lib/runtime/linux/thread.c')
-rw-r--r--src/lib/runtime/linux/thread.c282
1 files changed, 0 insertions, 282 deletions
diff --git a/src/lib/runtime/linux/thread.c b/src/lib/runtime/linux/thread.c
deleted file mode 100644
index cc9ba161b..000000000
--- a/src/lib/runtime/linux/thread.c
+++ /dev/null
@@ -1,282 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-#include "runtime.h"
-#include "defs.h"
-#include "signals.h"
-#include "os.h"
-
-// Linux futex.
-//
-// futexsleep(uint32 *addr, uint32 val)
-// futexwakeup(uint32 *addr)
-//
-// Futexsleep atomically checks if *addr == val and if so, sleeps on addr.
-// Futexwakeup wakes up one thread sleeping on addr.
-// Futexsleep is allowed to wake up spuriously.
-
-enum
-{
- FUTEX_WAIT = 0,
- FUTEX_WAKE = 1,
-
- EINTR = 4,
- EAGAIN = 11,
-};
-
-// TODO(rsc): I tried using 1<<40 here but futex woke up (-ETIMEDOUT).
-// I wonder if the timespec that gets to the kernel
-// actually has two 32-bit numbers in it, so that
-// a 64-bit 1<<40 ends up being 0 seconds,
-// 1<<8 nanoseconds.
-static Timespec longtime =
-{
- 1<<30, // 34 years
- 0
-};
-
-// Atomically,
-// if(*addr == val) sleep
-// Might be woken up spuriously; that's allowed.
-static void
-futexsleep(uint32 *addr, uint32 val)
-{
- int64 ret;
-
- ret = futex(addr, FUTEX_WAIT, val, &longtime, nil, 0);
- if(ret >= 0 || ret == -EAGAIN || ret == -EINTR)
- return;
-
- prints("futexsleep addr=");
- sys·printpointer(addr);
- prints(" val=");
- sys·printint(val);
- prints(" returned ");
- sys·printint(ret);
- prints("\n");
- *(int32*)0x1005 = 0x1005;
-}
-
-// If any procs are sleeping on addr, wake up at least one.
-static void
-futexwakeup(uint32 *addr)
-{
- int64 ret;
-
- ret = futex(addr, FUTEX_WAKE, 1, nil, nil, 0);
-
- if(ret >= 0)
- return;
-
- // I don't know that futex wakeup can return
- // EAGAIN or EINTR, but if it does, it would be
- // safe to loop and call futex again.
-
- prints("futexwakeup addr=");
- sys·printpointer(addr);
- prints(" returned ");
- sys·printint(ret);
- prints("\n");
- *(int32*)0x1006 = 0x1006;
-}
-
-
-// Lock and unlock.
-//
-// The lock state is a single 32-bit word that holds
-// a 31-bit count of threads waiting for the lock
-// and a single bit (the low bit) saying whether the lock is held.
-// The uncontended case runs entirely in user space.
-// When contention is detected, we defer to the kernel (futex).
-//
-// A reminder: compare-and-swap cas(addr, old, new) does
-// if(*addr == old) { *addr = new; return 1; }
-// else return 0;
-// but atomically.
-
-static void
-futexlock(Lock *l)
-{
- uint32 v;
-
-again:
- v = l->key;
- if((v&1) == 0){
- if(cas(&l->key, v, v|1)){
- // Lock wasn't held; we grabbed it.
- return;
- }
- goto again;
- }
-
- // Lock was held; try to add ourselves to the waiter count.
- if(!cas(&l->key, v, v+2))
- goto again;
-
- // We're accounted for, now sleep in the kernel.
- //
- // We avoid the obvious lock/unlock race because
- // the kernel won't put us to sleep if l->key has
- // changed underfoot and is no longer v+2.
- //
- // We only really care that (v&1) == 1 (the lock is held),
- // and in fact there is a futex variant that could
- // accomodate that check, but let's not get carried away.)
- futexsleep(&l->key, v+2);
-
- // We're awake: remove ourselves from the count.
- for(;;){
- v = l->key;
- if(v < 2)
- throw("bad lock key");
- if(cas(&l->key, v, v-2))
- break;
- }
-
- // Try for the lock again.
- goto again;
-}
-
-static void
-futexunlock(Lock *l)
-{
- uint32 v;
-
- // Atomically get value and clear lock bit.
-again:
- v = l->key;
- if((v&1) == 0)
- throw("unlock of unlocked lock");
- if(!cas(&l->key, v, v&~1))
- goto again;
-
- // If there were waiters, wake one.
- if(v & ~1)
- futexwakeup(&l->key);
-}
-
-void
-lock(Lock *l)
-{
- if(m->locks < 0)
- throw("lock count");
- m->locks++;
- futexlock(l);
-}
-
-void
-unlock(Lock *l)
-{
- m->locks--;
- if(m->locks < 0)
- throw("lock count");
- futexunlock(l);
-}
-
-
-// One-time notifications.
-//
-// Since the lock/unlock implementation already
-// takes care of sleeping in the kernel, we just reuse it.
-// (But it's a weird use, so it gets its own interface.)
-//
-// We use a lock to represent the event:
-// unlocked == event has happened.
-// Thus the lock starts out locked, and to wait for the
-// event you try to lock the lock. To signal the event,
-// you unlock the lock.
-
-void
-noteclear(Note *n)
-{
- n->lock.key = 0; // memset(n, 0, sizeof *n)
- futexlock(&n->lock);
-}
-
-void
-notewakeup(Note *n)
-{
- futexunlock(&n->lock);
-}
-
-void
-notesleep(Note *n)
-{
- futexlock(&n->lock);
- futexunlock(&n->lock); // Let other sleepers find out too.
-}
-
-
-// Clone, the Linux rfork.
-enum
-{
- CLONE_VM = 0x100,
- CLONE_FS = 0x200,
- CLONE_FILES = 0x400,
- CLONE_SIGHAND = 0x800,
- CLONE_PTRACE = 0x2000,
- CLONE_VFORK = 0x4000,
- CLONE_PARENT = 0x8000,
- CLONE_THREAD = 0x10000,
- CLONE_NEWNS = 0x20000,
- CLONE_SYSVSEM = 0x40000,
- CLONE_SETTLS = 0x80000,
- CLONE_PARENT_SETTID = 0x100000,
- CLONE_CHILD_CLEARTID = 0x200000,
- CLONE_UNTRACED = 0x800000,
- CLONE_CHILD_SETTID = 0x1000000,
- CLONE_STOPPED = 0x2000000,
- CLONE_NEWUTS = 0x4000000,
- CLONE_NEWIPC = 0x8000000,
-};
-
-void
-newosproc(M *m, G *g, void *stk, void (*fn)(void))
-{
- int64 ret;
- int32 flags;
-
- /*
- * note: strace gets confused if we use CLONE_PTRACE here.
- */
- flags = CLONE_PARENT /* getppid doesn't change in child */
- | CLONE_VM /* share memory */
- | CLONE_FS /* share cwd, etc */
- | CLONE_FILES /* share fd table */
- | CLONE_SIGHAND /* share sig handler table */
- | CLONE_THREAD /* revisit - okay for now */
- ;
-
- if(0){
- prints("newosproc stk=");
- sys·printpointer(stk);
- prints(" m=");
- sys·printpointer(m);
- prints(" g=");
- sys·printpointer(g);
- prints(" fn=");
- sys·printpointer(fn);
- prints(" clone=");
- sys·printpointer(clone);
- prints("\n");
- }
-
- ret = clone(flags, stk, m, g, fn);
- if(ret < 0)
- *(int32*)123 = 123;
-}
-
-void
-osinit(void)
-{
-}
-
-// Called to initialize a new m (including the bootstrap m).
-void
-minit(void)
-{
- // Initialize signal handling.
- m->gsignal = malg(32*1024); // OS X wants >=8K, Linux >=2K
- signalstack(m->gsignal->stackguard, 32*1024);
-}