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hold ptable.lock for the entire process creation

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however, processes still modify their own p->* without locking
This commit is contained in:
Robert Morris 2016-08-13 03:44:13 -04:00
parent 20d05d4411
commit 19f65413bd
2 changed files with 15 additions and 9 deletions
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4
Makefile
View file

@ -74,8 +74,8 @@ AS = $(TOOLPREFIX)gas
LD = $(TOOLPREFIX)ld LD = $(TOOLPREFIX)ld
OBJCOPY = $(TOOLPREFIX)objcopy OBJCOPY = $(TOOLPREFIX)objcopy
OBJDUMP = $(TOOLPREFIX)objdump OBJDUMP = $(TOOLPREFIX)objdump
#CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32 -Werror -fno-omit-frame-pointer CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32 -Werror -fno-omit-frame-pointer
CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -fvar-tracking -fvar-tracking-assignments -O0 -g -Wall -MD -gdwarf-2 -m32 -Werror -fno-omit-frame-pointer #CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -fvar-tracking -fvar-tracking-assignments -O0 -g -Wall -MD -gdwarf-2 -m32 -Werror -fno-omit-frame-pointer
CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector) CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
ASFLAGS = -m32 -gdwarf-2 -Wa,-divide ASFLAGS = -m32 -gdwarf-2 -Wa,-divide
# FreeBSD ld wants ``elf_i386_fbsd'' # FreeBSD ld wants ``elf_i386_fbsd''

20
proc.c
View file

@ -31,23 +31,21 @@ pinit(void)
// If found, change state to EMBRYO and initialize // If found, change state to EMBRYO and initialize
// state required to run in the kernel. // state required to run in the kernel.
// Otherwise return 0. // Otherwise return 0.
// Must hold ptable.lock.
static struct proc* static struct proc*
allocproc(void) allocproc(void)
{ {
struct proc *p; struct proc *p;
char *sp; char *sp;
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++) for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
if(p->state == UNUSED) if(p->state == UNUSED)
goto found; goto found;
release(&ptable.lock);
return 0; return 0;
found: found:
p->state = EMBRYO; p->state = EMBRYO;
p->pid = nextpid++; p->pid = nextpid++;
release(&ptable.lock);
// Allocate kernel stack. // Allocate kernel stack.
if((p->kstack = kalloc()) == 0){ if((p->kstack = kalloc()) == 0){
@ -81,6 +79,8 @@ userinit(void)
struct proc *p; struct proc *p;
extern char _binary_initcode_start[], _binary_initcode_size[]; extern char _binary_initcode_start[], _binary_initcode_size[];
acquire(&ptable.lock);
p = allocproc(); p = allocproc();
initproc = p; initproc = p;
if((p->pgdir = setupkvm()) == 0) if((p->pgdir = setupkvm()) == 0)
@ -100,6 +100,8 @@ userinit(void)
p->cwd = namei("/"); p->cwd = namei("/");
p->state = RUNNABLE; p->state = RUNNABLE;
release(&ptable.lock);
} }
// Grow current process's memory by n bytes. // Grow current process's memory by n bytes.
@ -131,15 +133,20 @@ fork(void)
int i, pid; int i, pid;
struct proc *np; struct proc *np;
acquire(&ptable.lock);
// Allocate process. // Allocate process.
if((np = allocproc()) == 0) if((np = allocproc()) == 0){
release(&ptable.lock);
return -1; return -1;
}
// Copy process state from p. // Copy process state from p.
if((np->pgdir = copyuvm(proc->pgdir, proc->sz)) == 0){ if((np->pgdir = copyuvm(proc->pgdir, proc->sz)) == 0){
kfree(np->kstack); kfree(np->kstack);
np->kstack = 0; np->kstack = 0;
np->state = UNUSED; np->state = UNUSED;
release(&ptable.lock);
return -1; return -1;
} }
np->sz = proc->sz; np->sz = proc->sz;
@ -158,9 +165,8 @@ fork(void)
pid = np->pid; pid = np->pid;
// lock to force the compiler to emit the np->state write last.
acquire(&ptable.lock);
np->state = RUNNABLE; np->state = RUNNABLE;
release(&ptable.lock); release(&ptable.lock);
return pid; return pid;
@ -233,11 +239,11 @@ wait(void)
kfree(p->kstack); kfree(p->kstack);
p->kstack = 0; p->kstack = 0;
freevm(p->pgdir); freevm(p->pgdir);
p->state = UNUSED;
p->pid = 0; p->pid = 0;
p->parent = 0; p->parent = 0;
p->name[0] = 0; p->name[0] = 0;
p->killed = 0; p->killed = 0;
p->state = UNUSED;
release(&ptable.lock); release(&ptable.lock);
return pid; return pid;
} }