diff options
Diffstat (limited to 'proc.c')
| -rw-r--r-- | proc.c | 20 |
1 files changed, 13 insertions, 7 deletions
@@ -31,23 +31,21 @@ 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){ @@ -81,6 +79,8 @@ userinit(void) struct proc *p; extern char _binary_initcode_start[], _binary_initcode_size[]; + acquire(&ptable.lock); + p = allocproc(); initproc = p; if((p->pgdir = setupkvm()) == 0) @@ -100,6 +100,8 @@ userinit(void) p->cwd = namei("/"); p->state = RUNNABLE; + + release(&ptable.lock); } // Grow current process's memory by n bytes. @@ -131,15 +133,20 @@ fork(void) int i, pid; struct proc *np; + acquire(&ptable.lock); + // Allocate process. - if((np = allocproc()) == 0) + if((np = allocproc()) == 0){ + release(&ptable.lock); return -1; + } // 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; @@ -158,9 +165,8 @@ fork(void) pid = np->pid; - // lock to force the compiler to emit the np->state write last. - acquire(&ptable.lock); np->state = RUNNABLE; + release(&ptable.lock); return pid; @@ -233,11 +239,11 @@ wait(void) kfree(p->kstack); p->kstack = 0; freevm(p->pgdir); - p->state = UNUSED; p->pid = 0; p->parent = 0; p->name[0] = 0; p->killed = 0; + p->state = UNUSED; release(&ptable.lock); return pid; } |