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Viewing changes to src/pkg/runtime/lock_sema.c

  • Committer: Package Import Robot
  • Author(s): James Page
  • Date: 2013-08-20 14:06:23 UTC
  • mfrom: (14.1.23 saucy-proposed)
  • Revision ID: package-import@ubuntu.com-20130820140623-b414jfxi3m0qkmrq
Tags: 2:1.1.2-2ubuntu1
https://launchpad.net/bugs/1211749
https://launchpad.net/bugs/1202027
* Merge from Debian unstable (LP: #1211749, #1202027). Remaining changes:
  - 016-armhf-elf-header.patch: Use correct ELF header for armhf binaries.
  - d/control,control.cross: Update Breaks/Replaces for Ubuntu
    versions to ensure smooth upgrades, regenerate control file.

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Lines of Context:
src/pkg/runtime/lock_sema.c
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                runtime·throw("runtime·lock: lock count");
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        // Speculative grab for lock.
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        if(runtime·casp(&l->waitm, nil, (void*)LOCKED))
 
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        if(runtime·casp((void**)&l->key, nil, (void*)LOCKED))
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                return;
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        if(m->waitsema == 0)
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                spin = ACTIVE_SPIN;
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        for(i=0;; i++) {
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                v = (uintptr)runtime·atomicloadp(&l->waitm);
 
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                v = (uintptr)runtime·atomicloadp((void**)&l->key);
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                if((v&LOCKED) == 0) {
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unlocked:
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                        if(runtime·casp(&l->waitm, (void*)v, (void*)(v|LOCKED)))
 
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                        if(runtime·casp((void**)&l->key, (void*)v, (void*)(v|LOCKED)))
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                                return;
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                        i = 0;
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                }
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                        // Queue this M.
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                        for(;;) {
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                                m->nextwaitm = (void*)(v&~LOCKED);
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                                if(runtime·casp(&l->waitm, (void*)v, (void*)((uintptr)m|LOCKED)))
 
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                                if(runtime·casp((void**)&l->key, (void*)v, (void*)((uintptr)m|LOCKED)))
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                                        break;
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                                v = (uintptr)runtime·atomicloadp(&l->waitm);
 
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                                v = (uintptr)runtime·atomicloadp((void**)&l->key);
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                                if((v&LOCKED) == 0)
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                                        goto unlocked;
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                        }
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                runtime·throw("runtime·unlock: lock count");
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        for(;;) {
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                v = (uintptr)runtime·atomicloadp(&l->waitm);
 
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                v = (uintptr)runtime·atomicloadp((void**)&l->key);
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                if(v == LOCKED) {
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                        if(runtime·casp(&l->waitm, (void*)LOCKED, nil))
 
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                        if(runtime·casp((void**)&l->key, (void*)LOCKED, nil))
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                                break;
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                } else {
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                        // Other M's are waiting for the lock.
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                        // Dequeue an M.
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                        mp = (void*)(v&~LOCKED);
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                        if(runtime·casp(&l->waitm, (void*)v, mp->nextwaitm)) {
 
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                        if(runtime·casp((void**)&l->key, (void*)v, mp->nextwaitm)) {
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                                // Dequeued an M.  Wake it.
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                                runtime·semawakeup(mp);
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                                break;
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void
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runtime·noteclear(Note *n)
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{
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        n->waitm = nil;
 
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        n->key = 0;
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}
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void
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        M *mp;
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        do
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                mp = runtime·atomicloadp(&n->waitm);
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        while(!runtime·casp(&n->waitm, mp, (void*)LOCKED));
 
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                mp = runtime·atomicloadp((void**)&n->key);
 
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        while(!runtime·casp((void**)&n->key, mp, (void*)LOCKED));
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        // Successfully set waitm to LOCKED.
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        // What was it before?
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{
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        if(m->waitsema == 0)
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                m->waitsema = runtime·semacreate();
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        if(!runtime·casp(&n->waitm, nil, m)) {  // must be LOCKED (got wakeup)
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                if(n->waitm != (void*)LOCKED)
 
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        if(!runtime·casp((void**)&n->key, nil, m)) {  // must be LOCKED (got wakeup)
 
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                if(n->key != LOCKED)
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                        runtime·throw("notesleep - waitm out of sync");
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                return;
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        }
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                m->waitsema = runtime·semacreate();
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        // Register for wakeup on n->waitm.
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        if(!runtime·casp(&n->waitm, nil, m)) {  // must be LOCKED (got wakeup already)
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                if(n->waitm != (void*)LOCKED)
 
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        if(!runtime·casp((void**)&n->key, nil, m)) {  // must be LOCKED (got wakeup already)
 
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                if(n->key != LOCKED)
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                        runtime·throw("notetsleep - waitm out of sync");
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                return;
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        }
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        // so that any notewakeup racing with the return does not
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        // try to grant us the semaphore when we don't expect it.
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        for(;;) {
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                mp = runtime·atomicloadp(&n->waitm);
 
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                mp = runtime·atomicloadp((void**)&n->key);
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                if(mp == m) {
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                        // No wakeup yet; unregister if possible.
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                        if(runtime·casp(&n->waitm, mp, nil))
 
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                        if(runtime·casp((void**)&n->key, mp, nil))
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                                return;
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                } else if(mp == (M*)LOCKED) {
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                        // Wakeup happened so semaphore is available.