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Push Giant deep into vm_forkproc(), acquiring it only if the process has

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mapped System V shared memory segments (see shmfork_myhook()) or requires
the allocation of an ldt (see vm_fault_wire()).
This commit is contained in:
Alan Cox 2004-09-03 05:11:32 +00:00
parent 2e3e26a50c
commit 94ddc7076d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=134675
5 changed files with 18 additions and 21 deletions
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28
sys/kern/kern_fork.c
View File

@ -219,9 +219,7 @@ fork1(td, flags, pages, procp)
* certain parts of a process from itself.
*/
if ((flags & RFPROC) == 0) {
mtx_lock(&Giant);
vm_forkproc(td, NULL, NULL, flags);
mtx_unlock(&Giant);
/*
* Close all file descriptors.
@ -668,27 +666,25 @@ fork1(td, flags, pages, procp)
* Finish creating the child process. It will return via a different
* execution path later. (ie: directly into user mode)
*/
mtx_lock(&Giant);
vm_forkproc(td, p2, td2, flags);
if (flags == (RFFDG | RFPROC)) {
cnt.v_forks++;
cnt.v_forkpages += p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize;
atomic_add_int(&cnt.v_forks, 1);
atomic_add_int(&cnt.v_forkpages, p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize);
} else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
cnt.v_vforks++;
cnt.v_vforkpages += p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize;
atomic_add_int(&cnt.v_vforks, 1);
atomic_add_int(&cnt.v_vforkpages, p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize);
} else if (p1 == &proc0) {
cnt.v_kthreads++;
cnt.v_kthreadpages += p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize;
atomic_add_int(&cnt.v_kthreads, 1);
atomic_add_int(&cnt.v_kthreadpages, p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize);
} else {
cnt.v_rforks++;
cnt.v_rforkpages += p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize;
atomic_add_int(&cnt.v_rforks, 1);
atomic_add_int(&cnt.v_rforkpages, p2->p_vmspace->vm_dsize +
p2->p_vmspace->vm_ssize);
}
mtx_unlock(&Giant);
/*
* Both processes are set up, now check if any loadable modules want

2
sys/kern/sysv_shm.c
View File

@ -806,6 +806,7 @@ shmfork_myhook(p1, p2)
size_t size;
int i;
mtx_lock(&Giant);
size = shminfo.shmseg * sizeof(struct shmmap_state);
shmmap_s = malloc(size, M_SHM, M_WAITOK);
bcopy(p1->p_vmspace->vm_shm, shmmap_s, size);
@ -813,6 +814,7 @@ shmfork_myhook(p1, p2)
for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
if (shmmap_s->shmid != -1)
shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
mtx_unlock(&Giant);
}
static void

4
sys/vm/vm_fault.c
View File

@ -1026,9 +1026,13 @@ vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
* read-only sections.
*/
for (va = start; va < end; va += PAGE_SIZE) {
if (map->system_map)
mtx_lock(&Giant);
rv = vm_fault(map, va,
user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE,
user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING);
if (map->system_map)
mtx_unlock(&Giant);
if (rv) {
if (va != start)
vm_fault_unwire(map, start, va, fictitious);

2
sys/vm/vm_glue.c
View File

@ -619,8 +619,6 @@ vm_forkproc(td, p2, td2, flags)
{
struct proc *p1 = td->td_proc;
GIANT_REQUIRED;
if ((flags & RFPROC) == 0) {
/*
* Divorce the memory, if it is shared, essentially

3
sys/vm/vm_map.c
View File

@ -2482,8 +2482,6 @@ vmspace_fork(struct vmspace *vm1)
vm_map_entry_t new_entry;
vm_object_t object;
GIANT_REQUIRED;
vm_map_lock(old_map);
vm2 = vmspace_alloc(old_map->min_offset, old_map->max_offset);
@ -2942,7 +2940,6 @@ vmspace_unshare(struct proc *p)
struct vmspace *oldvmspace = p->p_vmspace;
struct vmspace *newvmspace;
GIANT_REQUIRED;
if (oldvmspace->vm_refcnt == 1)
return;
newvmspace = vmspace_fork(oldvmspace);