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- #include "u.h"
- #include "../port/lib.h"
- #include "mem.h"
- #include "dat.h"
- #include "fns.h"
- #include "../port/error.h"
- #include "edf.h"
- uvlong maxlockcycles;
- uvlong maxilockcycles;
- ulong maxlockpc;
- ulong maxilockpc;
- struct
- {
- ulong locks;
- ulong glare;
- ulong inglare;
- } lockstats;
- static void
- inccnt(Ref *r)
- {
- _xinc(&r->ref);
- }
- static int
- deccnt(Ref *r)
- {
- int x;
- x = _xdec(&r->ref);
- if(x < 0)
- panic("deccnt pc=0x%lux", getcallerpc(&r));
- return x;
- }
- static void
- dumplockmem(char *tag, Lock *l)
- {
- uchar *cp;
- int i;
- iprint("%s: ", tag);
- cp = (uchar*)l;
- for(i = 0; i < 64; i++)
- iprint("%2.2ux ", cp[i]);
- iprint("\n");
- }
- void
- lockloop(Lock *l, ulong pc)
- {
- Proc *p;
- p = l->p;
- print("lock 0x%lux loop key 0x%lux pc 0x%lux held by pc 0x%lux proc %lud\n",
- l, l->key, pc, l->pc, p ? p->pid : 0);
- dumpaproc(up);
- if(p != nil)
- dumpaproc(p);
- }
- int
- lock(Lock *l)
- {
- int i;
- ulong pc;
- pc = getcallerpc(&l);
- lockstats.locks++;
- if(up)
- inccnt(&up->nlocks); /* prevent being scheded */
- if(tas(&l->key) == 0){
- if(up)
- up->lastlock = l;
- l->pc = pc;
- l->p = up;
- l->isilock = 0;
- #ifdef LOCKCYCLES
- cycles(&l->lockcycles);
- #endif
- return 0;
- }
- if(up)
- deccnt(&up->nlocks);
- lockstats.glare++;
- for(;;){
- lockstats.inglare++;
- i = 0;
- while(l->key){
- if(conf.nmach < 2 && up && up->edf && (up->edf->flags & Admitted)){
- /*
- * Priority inversion, yield on a uniprocessor; on a
- * multiprocessor, the other processor will unlock
- */
- print("inversion 0x%lux pc 0x%lux proc %lud held by pc 0x%lux proc %lud\n",
- l, pc, up ? up->pid : 0, l->pc, l->p ? l->p->pid : 0);
- up->edf->d = todget(nil); /* yield to process with lock */
- }
- if(i++ > 100000000){
- i = 0;
- lockloop(l, pc);
- }
- }
- if(up)
- inccnt(&up->nlocks);
- if(tas(&l->key) == 0){
- if(up)
- up->lastlock = l;
- l->pc = pc;
- l->p = up;
- l->isilock = 0;
- #ifdef LOCKCYCLES
- cycles(&l->lockcycles);
- #endif
- return 1;
- }
- if(up)
- deccnt(&up->nlocks);
- }
- }
- void
- ilock(Lock *l)
- {
- ulong x;
- ulong pc;
- pc = getcallerpc(&l);
- lockstats.locks++;
- x = splhi();
- if(tas(&l->key) != 0){
- lockstats.glare++;
- /*
- * Cannot also check l->pc and l->m here because
- * they might just not be set yet, or the lock might
- * even have been let go.
- */
- if(!l->isilock){
- dumplockmem("ilock:", l);
- panic("corrupt ilock %p pc=%luX m=%p isilock=%d",
- l, l->pc, l->m, l->isilock);
- }
- if(l->m == MACHP(m->machno))
- panic("ilock: deadlock on cpu%d pc=%luX lockpc=%luX\n",
- m->machno, pc, l->pc);
- for(;;){
- lockstats.inglare++;
- splx(x);
- while(l->key)
- ;
- x = splhi();
- if(tas(&l->key) == 0)
- goto acquire;
- }
- }
- acquire:
- m->ilockdepth++;
- if(up)
- up->lastilock = l;
- l->sr = x;
- l->pc = pc;
- l->p = up;
- l->isilock = 1;
- l->m = MACHP(m->machno);
- #ifdef LOCKCYCLES
- cycles(&l->lockcycles);
- #endif
- }
- int
- canlock(Lock *l)
- {
- if(up)
- inccnt(&up->nlocks);
- if(tas(&l->key)){
- if(up)
- deccnt(&up->nlocks);
- return 0;
- }
- if(up)
- up->lastlock = l;
- l->pc = getcallerpc(&l);
- l->p = up;
- l->m = MACHP(m->machno);
- l->isilock = 0;
- #ifdef LOCKCYCLES
- cycles(&l->lockcycles);
- #endif
- return 1;
- }
- void
- unlock(Lock *l)
- {
- #ifdef LOCKCYCLES
- uvlong x;
- cycles(&x);
- l->lockcycles = x - l->lockcycles;
- if(l->lockcycles > maxlockcycles){
- maxlockcycles = l->lockcycles;
- maxlockpc = l->pc;
- }
- #endif
- if(l->key == 0)
- print("unlock: not locked: pc %luX\n", getcallerpc(&l));
- if(l->isilock)
- print("unlock of ilock: pc %lux, held by %lux\n", getcallerpc(&l), l->pc);
- if(l->p != up)
- print("unlock: up changed: pc %lux, acquired at pc %lux, lock p 0x%p, unlock up 0x%p\n", getcallerpc(&l), l->pc, l->p, up);
- l->m = nil;
- l->key = 0;
- coherence();
- if(up && deccnt(&up->nlocks) == 0 && up->delaysched && islo()){
- /*
- * Call sched if the need arose while locks were held
- * But, don't do it from interrupt routines, hence the islo() test
- */
- sched();
- }
- }
- void
- iunlock(Lock *l)
- {
- ulong sr;
- #ifdef LOCKCYCLES
- uvlong x;
- cycles(&x);
- l->lockcycles = x - l->lockcycles;
- if(l->lockcycles > maxilockcycles){
- maxilockcycles = l->lockcycles;
- maxilockpc = l->pc;
- }
- #endif
- if(l->key == 0)
- print("iunlock: not locked: pc %luX\n", getcallerpc(&l));
- if(!l->isilock)
- print("iunlock of lock: pc %lux, held by %lux\n", getcallerpc(&l), l->pc);
- if(islo())
- print("iunlock while lo: pc %lux, held by %lux\n", getcallerpc(&l), l->pc);
- sr = l->sr;
- l->m = nil;
- l->key = 0;
- coherence();
- m->ilockdepth--;
- if(up)
- up->lastilock = nil;
- splx(sr);
- }
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