freebsd-dev/sys/dev/drm/drm_lock.c
Warner Losh 592ffb2175 Revert drm2 removal.
Revert r338177, r338176, r338175, r338174, r338172

After long consultations with re@, core members and mmacy, revert
these changes. Followup changes will be made to mark them as
deprecated and prent a message about where to find the up-to-date
driver.  Followup commits will be made to make this clear in the
installer. Followup commits to reduce POLA in ways we're still
exploring.

It's anticipated that after the freeze, this will be removed in
13-current (with the residual of the drm2 code copied to
sys/arm/dev/drm2 for the TEGRA port's use w/o the intel or
radeon drivers).

Due to the impending freeze, there was no formal core vote for
this. I've been talking to different core members all day, as well as
Matt Macey and Glen Barber. Nobody is completely happy, all are
grudgingly going along with this. Work is in progress to mitigate
the negative effects as much as possible.

Requested by: re@ (gjb, rgrimes)
2018-08-24 00:02:00 +00:00

200 lines
5.6 KiB
C

/*-
* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Authors:
* Rickard E. (Rik) Faith <faith@valinux.com>
* Gareth Hughes <gareth@valinux.com>
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/** @file drm_lock.c
* Implementation of the ioctls and other support code for dealing with the
* hardware lock.
*
* The DRM hardware lock is a shared structure between the kernel and userland.
*
* On uncontended access where the new context was the last context, the
* client may take the lock without dropping down into the kernel, using atomic
* compare-and-set.
*
* If the client finds during compare-and-set that it was not the last owner
* of the lock, it calls the DRM lock ioctl, which may sleep waiting for the
* lock, and may have side-effects of kernel-managed context switching.
*
* When the client releases the lock, if the lock is marked as being contended
* by another client, then the DRM unlock ioctl is called so that the
* contending client may be woken up.
*/
#include "dev/drm/drmP.h"
int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
struct drm_lock *lock = data;
int ret = 0;
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
DRM_CURRENTPID, lock->context);
return EINVAL;
}
DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
lock->flags);
if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE) &&
lock->context < 0)
return EINVAL;
DRM_LOCK();
for (;;) {
if (drm_lock_take(&dev->lock, lock->context)) {
dev->lock.file_priv = file_priv;
dev->lock.lock_time = jiffies;
atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
break; /* Got lock */
}
/* Contention */
ret = mtx_sleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
PCATCH, "drmlk2", 0);
if (ret != 0)
break;
}
DRM_UNLOCK();
if (ret == ERESTART)
DRM_DEBUG("restarting syscall\n");
else
DRM_DEBUG("%d %s\n", lock->context,
ret ? "interrupted" : "has lock");
if (ret != 0)
return ret;
/* XXX: Add signal blocking here */
if (dev->driver->dma_quiescent != NULL &&
(lock->flags & _DRM_LOCK_QUIESCENT))
dev->driver->dma_quiescent(dev);
return 0;
}
int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
struct drm_lock *lock = data;
DRM_DEBUG("%d (pid %d) requests unlock (0x%08x), flags = 0x%08x\n",
lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
lock->flags);
if (lock->context == DRM_KERNEL_CONTEXT) {
DRM_ERROR("Process %d using kernel context %d\n",
DRM_CURRENTPID, lock->context);
return EINVAL;
}
atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
DRM_LOCK();
drm_lock_transfer(&dev->lock, DRM_KERNEL_CONTEXT);
if (drm_lock_free(&dev->lock, DRM_KERNEL_CONTEXT)) {
DRM_ERROR("\n");
}
DRM_UNLOCK();
return 0;
}
int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context)
{
volatile unsigned int *lock = &lock_data->hw_lock->lock;
unsigned int old, new;
do {
old = *lock;
if (old & _DRM_LOCK_HELD)
new = old | _DRM_LOCK_CONT;
else
new = context | _DRM_LOCK_HELD;
} while (!atomic_cmpset_int(lock, old, new));
if (_DRM_LOCKING_CONTEXT(old) == context) {
if (old & _DRM_LOCK_HELD) {
if (context != DRM_KERNEL_CONTEXT) {
DRM_ERROR("%d holds heavyweight lock\n",
context);
}
return 0;
}
}
if (new == (context | _DRM_LOCK_HELD)) {
/* Have lock */
return 1;
}
return 0;
}
/* This takes a lock forcibly and hands it to context. Should ONLY be used
inside *_unlock to give lock to kernel before calling *_dma_schedule. */
int drm_lock_transfer(struct drm_lock_data *lock_data, unsigned int context)
{
volatile unsigned int *lock = &lock_data->hw_lock->lock;
unsigned int old, new;
lock_data->file_priv = NULL;
do {
old = *lock;
new = context | _DRM_LOCK_HELD;
} while (!atomic_cmpset_int(lock, old, new));
return 1;
}
int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
{
volatile unsigned int *lock = &lock_data->hw_lock->lock;
unsigned int old, new;
lock_data->file_priv = NULL;
do {
old = *lock;
new = 0;
} while (!atomic_cmpset_int(lock, old, new));
if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
DRM_ERROR("%d freed heavyweight lock held by %d\n",
context, _DRM_LOCKING_CONTEXT(old));
return 1;
}
DRM_WAKEUP_INT((void *)&lock_data->lock_queue);
return 0;
}