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authorChristoph Lameter <cl@linux.com>2017-07-12 14:33:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-12 16:25:59 -0700
commit112166f88cf83dd11486cf1818672d42b540865b (patch)
treea111199c9d0cb26065fc0023879f53d904657d1f
parent91a90140f9987101d730b7dad8c6406321285da8 (diff)
kernel/fork.c: virtually mapped stacks: do not disable interrupts
The reason to disable interrupts seems to be to avoid switching to a different processor while handling per cpu data using individual loads and stores. If we use per cpu RMV primitives we will not have to disable interrupts. Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1705171055130.5898@east.gentwo.org Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/fork.c16
1 files changed, 5 insertions, 11 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 0f69a3e5281e..d2b9d7c31eaf 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -205,19 +205,17 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
void *stack;
int i;
- local_irq_disable();
for (i = 0; i < NR_CACHED_STACKS; i++) {
- struct vm_struct *s = this_cpu_read(cached_stacks[i]);
+ struct vm_struct *s;
+
+ s = this_cpu_xchg(cached_stacks[i], NULL);
if (!s)
continue;
- this_cpu_write(cached_stacks[i], NULL);
tsk->stack_vm_area = s;
- local_irq_enable();
return s->addr;
}
- local_irq_enable();
stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE,
VMALLOC_START, VMALLOC_END,
@@ -245,19 +243,15 @@ static inline void free_thread_stack(struct task_struct *tsk)
{
#ifdef CONFIG_VMAP_STACK
if (task_stack_vm_area(tsk)) {
- unsigned long flags;
int i;
- local_irq_save(flags);
for (i = 0; i < NR_CACHED_STACKS; i++) {
- if (this_cpu_read(cached_stacks[i]))
+ if (this_cpu_cmpxchg(cached_stacks[i],
+ NULL, tsk->stack_vm_area) != NULL)
continue;
- this_cpu_write(cached_stacks[i], tsk->stack_vm_area);
- local_irq_restore(flags);
return;
}
- local_irq_restore(flags);
vfree_atomic(tsk->stack);
return;