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author | Ondřej Surý <ondrej@sury.org> | 2011-09-13 13:11:55 +0200 |
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committer | Ondřej Surý <ondrej@sury.org> | 2011-09-13 13:11:55 +0200 |
commit | 80f18fc933cf3f3e829c5455a1023d69f7b86e52 (patch) | |
tree | 4b825dc642cb6eb9a060e54bf8d69288fbee4904 /src/pkg/runtime/linux/thread.c | |
parent | 28592ee1ea1f5cdffcf85472f9de0285d928cf12 (diff) | |
download | golang-80f18fc933cf3f3e829c5455a1023d69f7b86e52.tar.gz |
Imported Upstream version 60
Diffstat (limited to 'src/pkg/runtime/linux/thread.c')
-rw-r--r-- | src/pkg/runtime/linux/thread.c | 305 |
1 files changed, 0 insertions, 305 deletions
diff --git a/src/pkg/runtime/linux/thread.c b/src/pkg/runtime/linux/thread.c deleted file mode 100644 index 7c7ca7b4e..000000000 --- a/src/pkg/runtime/linux/thread.c +++ /dev/null @@ -1,305 +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 "os.h" -#include "stack.h" - -extern SigTab runtime·sigtab[]; - -// 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) -{ - // Some Linux kernels have a bug where futex of - // FUTEX_WAIT returns an internal error code - // as an errno. Libpthread ignores the return value - // here, and so can we: as it says a few lines up, - // spurious wakeups are allowed. - runtime·futex(addr, FUTEX_WAIT, val, &longtime, nil, 0); -} - -// If any procs are sleeping on addr, wake up at least one. -static void -futexwakeup(uint32 *addr) -{ - int64 ret; - - ret = runtime·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. - - runtime·prints("futexwakeup addr="); - runtime·printpointer(addr); - runtime·prints(" returned "); - runtime·printint(ret); - runtime·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 runtime·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(runtime·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(!runtime·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 - // accommodate 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) - runtime·throw("bad lock key"); - if(runtime·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) - runtime·throw("unlock of unlocked lock"); - if(!runtime·cas(&l->key, v, v&~1)) - goto again; - - // If there were waiters, wake one. - if(v & ~1) - futexwakeup(&l->key); -} - -void -runtime·lock(Lock *l) -{ - if(m->locks < 0) - runtime·throw("lock count"); - m->locks++; - futexlock(l); -} - -void -runtime·unlock(Lock *l) -{ - m->locks--; - if(m->locks < 0) - runtime·throw("lock count"); - futexunlock(l); -} - -void -runtime·destroylock(Lock*) -{ -} - - -// 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 -runtime·noteclear(Note *n) -{ - n->lock.key = 0; // memset(n, 0, sizeof *n) - futexlock(&n->lock); -} - -void -runtime·notewakeup(Note *n) -{ - futexunlock(&n->lock); -} - -void -runtime·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 -runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void)) -{ - int32 ret; - int32 flags; - - /* - * note: strace gets confused if we use CLONE_PTRACE here. - */ - flags = 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 */ - ; - - m->tls[0] = m->id; // so 386 asm can find it - if(0){ - runtime·printf("newosproc stk=%p m=%p g=%p fn=%p clone=%p id=%d/%d ostk=%p\n", - stk, m, g, fn, runtime·clone, m->id, m->tls[0], &m); - } - - if((ret = runtime·clone(flags, stk, m, g, fn)) < 0) { - runtime·printf("runtime: failed to create new OS thread (have %d already; errno=%d)\n", runtime·mcount(), -ret); - runtime·throw("runtime.newosproc"); - } -} - -void -runtime·osinit(void) -{ -} - -void -runtime·goenvs(void) -{ - runtime·goenvs_unix(); -} - -// Called to initialize a new m (including the bootstrap m). -void -runtime·minit(void) -{ - // Initialize signal handling. - m->gsignal = runtime·malg(32*1024); // OS X wants >=8K, Linux >=2K - runtime·signalstack(m->gsignal->stackguard - StackGuard, 32*1024); -} - -void -runtime·sigpanic(void) -{ - switch(g->sig) { - case SIGBUS: - if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000) - runtime·panicstring("invalid memory address or nil pointer dereference"); - runtime·printf("unexpected fault address %p\n", g->sigcode1); - runtime·throw("fault"); - case SIGSEGV: - if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000) - runtime·panicstring("invalid memory address or nil pointer dereference"); - runtime·printf("unexpected fault address %p\n", g->sigcode1); - runtime·throw("fault"); - case SIGFPE: - switch(g->sigcode0) { - case FPE_INTDIV: - runtime·panicstring("integer divide by zero"); - case FPE_INTOVF: - runtime·panicstring("integer overflow"); - } - runtime·panicstring("floating point error"); - } - runtime·panicstring(runtime·sigtab[g->sig].name); -} |