66 строки
1.7 KiB
C
66 строки
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/* Copyright (c) 2021 Facebook
|
|
*/
|
|
|
|
#ifndef __MMAP_UNLOCK_WORK_H__
|
|
#define __MMAP_UNLOCK_WORK_H__
|
|
#include <linux/irq_work.h>
|
|
|
|
/* irq_work to run mmap_read_unlock() in irq_work */
|
|
struct mmap_unlock_irq_work {
|
|
struct irq_work irq_work;
|
|
struct mm_struct *mm;
|
|
};
|
|
|
|
DECLARE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
|
|
|
|
/*
|
|
* We cannot do mmap_read_unlock() when the irq is disabled, because of
|
|
* risk to deadlock with rq_lock. To look up vma when the irqs are
|
|
* disabled, we need to run mmap_read_unlock() in irq_work. We use a
|
|
* percpu variable to do the irq_work. If the irq_work is already used
|
|
* by another lookup, we fall over.
|
|
*/
|
|
static inline bool bpf_mmap_unlock_get_irq_work(struct mmap_unlock_irq_work **work_ptr)
|
|
{
|
|
struct mmap_unlock_irq_work *work = NULL;
|
|
bool irq_work_busy = false;
|
|
|
|
if (irqs_disabled()) {
|
|
if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
|
|
work = this_cpu_ptr(&mmap_unlock_work);
|
|
if (irq_work_is_busy(&work->irq_work)) {
|
|
/* cannot queue more up_read, fallback */
|
|
irq_work_busy = true;
|
|
}
|
|
} else {
|
|
/*
|
|
* PREEMPT_RT does not allow to trylock mmap sem in
|
|
* interrupt disabled context. Force the fallback code.
|
|
*/
|
|
irq_work_busy = true;
|
|
}
|
|
}
|
|
|
|
*work_ptr = work;
|
|
return irq_work_busy;
|
|
}
|
|
|
|
static inline void bpf_mmap_unlock_mm(struct mmap_unlock_irq_work *work, struct mm_struct *mm)
|
|
{
|
|
if (!work) {
|
|
mmap_read_unlock(mm);
|
|
} else {
|
|
work->mm = mm;
|
|
|
|
/* The lock will be released once we're out of interrupt
|
|
* context. Tell lockdep that we've released it now so
|
|
* it doesn't complain that we forgot to release it.
|
|
*/
|
|
rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_);
|
|
irq_work_queue(&work->irq_work);
|
|
}
|
|
}
|
|
|
|
#endif /* __MMAP_UNLOCK_WORK_H__ */
|