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proc_tree_lock -> wait_lock

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Robert Morris 2020-11-05 09:47:59 -05:00 committed by Frans Kaashoek
parent ba8d9f4808
commit 38084bcea8
1 changed files with 15 additions and 14 deletions
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29
kernel/proc.c
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@ -20,10 +20,11 @@ static void freeproc(struct proc *p);
extern char trampoline[]; // trampoline.S extern char trampoline[]; // trampoline.S
// protects parent/child relationships. // helps ensure that wakeups of wait()ing
// must be held when using p->parent. // parents are not lost. helps obey the
// memory model when using p->parent.
// must be acquired before any p->lock. // must be acquired before any p->lock.
struct spinlock proc_tree_lock; struct spinlock wait_lock;
// Allocate a page for each process's kernel stack. // Allocate a page for each process's kernel stack.
// Map it high in memory, followed by an invalid // Map it high in memory, followed by an invalid
@ -48,7 +49,7 @@ procinit(void)
struct proc *p; struct proc *p;
initlock(&pid_lock, "nextpid"); initlock(&pid_lock, "nextpid");
initlock(&proc_tree_lock, "proc_tree"); initlock(&wait_lock, "wait_lock");
for(p = proc; p < &proc[NPROC]; p++) { for(p = proc; p < &proc[NPROC]; p++) {
initlock(&p->lock, "proc"); initlock(&p->lock, "proc");
p->kstack = KSTACK((int) (p - proc)); p->kstack = KSTACK((int) (p - proc));
@ -306,9 +307,9 @@ fork(void)
release(&np->lock); release(&np->lock);
acquire(&proc_tree_lock); acquire(&wait_lock);
np->parent = p; np->parent = p;
release(&proc_tree_lock); release(&wait_lock);
acquire(&np->lock); acquire(&np->lock);
np->state = RUNNABLE; np->state = RUNNABLE;
@ -318,7 +319,7 @@ fork(void)
} }
// Pass p's abandoned children to init. // Pass p's abandoned children to init.
// Caller must hold proc_tree_lock. // Caller must hold wait_lock.
void void
reparent(struct proc *p) reparent(struct proc *p)
{ {
@ -357,7 +358,7 @@ exit(int status)
end_op(); end_op();
p->cwd = 0; p->cwd = 0;
acquire(&proc_tree_lock); acquire(&wait_lock);
// Give any children to init. // Give any children to init.
reparent(p); reparent(p);
@ -370,7 +371,7 @@ exit(int status)
p->xstate = status; p->xstate = status;
p->state = ZOMBIE; p->state = ZOMBIE;
release(&proc_tree_lock); release(&wait_lock);
// Jump into the scheduler, never to return. // Jump into the scheduler, never to return.
sched(); sched();
@ -386,7 +387,7 @@ wait(uint64 addr)
int havekids, pid; int havekids, pid;
struct proc *p = myproc(); struct proc *p = myproc();
acquire(&proc_tree_lock); acquire(&wait_lock);
for(;;){ for(;;){
// Scan through table looking for exited children. // Scan through table looking for exited children.
@ -403,12 +404,12 @@ wait(uint64 addr)
if(addr != 0 && copyout(p->pagetable, addr, (char *)&np->xstate, if(addr != 0 && copyout(p->pagetable, addr, (char *)&np->xstate,
sizeof(np->xstate)) < 0) { sizeof(np->xstate)) < 0) {
release(&np->lock); release(&np->lock);
release(&proc_tree_lock); release(&wait_lock);
return -1; return -1;
} }
freeproc(np); freeproc(np);
release(&np->lock); release(&np->lock);
release(&proc_tree_lock); release(&wait_lock);
return pid; return pid;
} }
release(&np->lock); release(&np->lock);
@ -417,12 +418,12 @@ wait(uint64 addr)
// No point waiting if we don't have any children. // No point waiting if we don't have any children.
if(!havekids || p->killed){ if(!havekids || p->killed){
release(&proc_tree_lock); release(&wait_lock);
return -1; return -1;
} }
// Wait for a child to exit. // Wait for a child to exit.
sleep(p, &proc_tree_lock); //DOC: wait-sleep sleep(p, &wait_lock); //DOC: wait-sleep
} }
} }