diff options
| -rw-r--r-- | proc.c | 20 | ||||
| -rw-r--r-- | spinlock.c | 2 |
2 files changed, 7 insertions, 15 deletions
@@ -31,22 +31,27 @@ pinit(void) // If found, change state to EMBRYO and initialize // state required to run in the kernel. // Otherwise return 0. -// Must hold ptable.lock. static struct proc* allocproc(void) { struct proc *p; char *sp; + acquire(&ptable.lock); + for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) if(p->state == UNUSED) goto found; + + release(&ptable.lock); return 0; found: p->state = EMBRYO; p->pid = nextpid++; + release(&ptable.lock); + // Allocate kernel stack. if((p->kstack = kalloc()) == 0){ p->state = UNUSED; @@ -79,14 +84,7 @@ userinit(void) struct proc *p; extern char _binary_initcode_start[], _binary_initcode_size[]; - acquire(&ptable.lock); - p = allocproc(); - - // release the lock in case namei() sleeps. - // the lock isn't needed because no other - // thread will look at an EMBRYO proc. - release(&ptable.lock); initproc = p; if((p->pgdir = setupkvm()) == 0) @@ -145,22 +143,16 @@ fork(void) int i, pid; struct proc *np; - acquire(&ptable.lock); - // Allocate process. if((np = allocproc()) == 0){ - release(&ptable.lock); return -1; } - release(&ptable.lock); - // Copy process state from p. if((np->pgdir = copyuvm(proc->pgdir, proc->sz)) == 0){ kfree(np->kstack); np->kstack = 0; np->state = UNUSED; - release(&ptable.lock); return -1; } np->sz = proc->sz; @@ -56,7 +56,7 @@ release(struct spinlock *lk) // past this point, to ensure that all the stores in the critical // section are visible to other cores before the lock is released. // Both the C compiler and the hardware may re-order loads and - // stores; __sync_synchronize() tells them both to not re-order. + // stores; __sync_synchronize() tells them both not to. __sync_synchronize(); // Release the lock, equivalent to lk->locked = 0. |