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author | Rob Pike <r@golang.org> | 2009-06-09 09:53:44 -0700 |
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committer | Rob Pike <r@golang.org> | 2009-06-09 09:53:44 -0700 |
commit | 7249ea4df2b4f12a4e7ed446f270cea87e4ffd34 (patch) | |
tree | 7032a11d0cac2ae4d3e90f7a189b575b5a50f848 /src/lib/runtime/linux/thread.c | |
parent | acf6ef7a82b3fe61516a1bac4563706552bdf078 (diff) | |
download | golang-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.c | 282 |
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); -} |