Messages in this thread Patch in this message | | | Date | Wed, 17 May 2017 10:58:26 -0500 (CDT) | From | Christoph Lameter <> | Subject | Virtually Mapped Stacks: Do not disable interrupts |
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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.
Signed-off-by: Christoph Lameter <cl@linux.com>
Index: linux/kernel/fork.c =================================================================== --- linux.orig/kernel/fork.c +++ linux/kernel/fork.c @@ -205,19 +205,17 @@ static unsigned long *alloc_thread_stack 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(str { #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;
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