Imbus/xv6-riscv-kernel
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avoid a double-lock of initproc->lock if child of init is reparenting

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This commit is contained in:
Robert Morris 2019-07-07 07:03:28 -04:00
parent 7114bf43ed
commit c4f6a241cd
1 changed files with 5 additions and 2 deletions
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7
kernel/proc.c
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@ -292,6 +292,7 @@ fork(void)
// are locked. // are locked.
void reparent(struct proc *p, struct proc *parent) { void reparent(struct proc *p, struct proc *parent) {
struct proc *pp; struct proc *pp;
int init_is_my_parent = (p->parent == initproc);
for(pp = ptable.proc; pp < &ptable.proc[NPROC]; pp++){ for(pp = ptable.proc; pp < &ptable.proc[NPROC]; pp++){
if (pp != p && pp != parent) { if (pp != p && pp != parent) {
@ -299,9 +300,11 @@ void reparent(struct proc *p, struct proc *parent) {
if(pp->parent == p){ if(pp->parent == p){
pp->parent = initproc; pp->parent = initproc;
if(pp->state == ZOMBIE) { if(pp->state == ZOMBIE) {
acquire(&initproc->lock); if(!init_is_my_parent)
acquire(&initproc->lock);
wakeup1(initproc); wakeup1(initproc);
release(&initproc->lock); if(!init_is_my_parent)
release(&initproc->lock);
} }
} }
release(&pp->lock); release(&pp->lock);