linux/drivers/gpu/drm/drm_fops.c
Arnd Bergmann 58374713c9 drm: kill BKL from common code
This restricts the use of the big kernel lock to the i830 and i810
device drivers. The three remaining users in common code (open, ioctl
and release) get converted to a new mutex, the drm_global_mutex,
making the locking stricter than the big kernel lock.

This may have a performance impact, but only in those cases that
currently don't use DRM_UNLOCKED flag in the ioctl list and would
benefit from that anyway.

The reason why i810 and i830 cannot use drm_global_mutex in their
mmap functions is a lock-order inversion problem between the current
use of the BKL and mmap_sem in these drivers. Since the BKL has
release-on-sleep semantics, it's harmless but it would cause trouble
if we replace the BKL with a mutex.

Instead, these drivers get their own ioctl wrappers that take the
BKL around every ioctl call and then set their own handlers as
DRM_UNLOCKED.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-08-05 11:54:40 +10:00

662 lines
17 KiB
C

/**
* \file drm_fops.c
* File operations for DRM
*
* \author Rickard E. (Rik) Faith <faith@valinux.com>
* \author Daryll Strauss <daryll@valinux.com>
* \author Gareth Hughes <gareth@valinux.com>
*/
/*
* Created: Mon Jan 4 08:58:31 1999 by faith@valinux.com
*
* 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.
*/
#include "drmP.h"
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
/* from BKL pushdown: note that nothing else serializes idr_find() */
DEFINE_MUTEX(drm_global_mutex);
static int drm_open_helper(struct inode *inode, struct file *filp,
struct drm_device * dev);
static int drm_setup(struct drm_device * dev)
{
int i;
int ret;
if (dev->driver->firstopen) {
ret = dev->driver->firstopen(dev);
if (ret != 0)
return ret;
}
atomic_set(&dev->ioctl_count, 0);
atomic_set(&dev->vma_count, 0);
if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
!drm_core_check_feature(dev, DRIVER_MODESET)) {
dev->buf_use = 0;
atomic_set(&dev->buf_alloc, 0);
i = drm_dma_setup(dev);
if (i < 0)
return i;
}
for (i = 0; i < ARRAY_SIZE(dev->counts); i++)
atomic_set(&dev->counts[i], 0);
dev->sigdata.lock = NULL;
dev->queue_count = 0;
dev->queue_reserved = 0;
dev->queue_slots = 0;
dev->queuelist = NULL;
dev->context_flag = 0;
dev->interrupt_flag = 0;
dev->dma_flag = 0;
dev->last_context = 0;
dev->last_switch = 0;
dev->last_checked = 0;
init_waitqueue_head(&dev->context_wait);
dev->if_version = 0;
dev->ctx_start = 0;
dev->lck_start = 0;
dev->buf_async = NULL;
init_waitqueue_head(&dev->buf_readers);
init_waitqueue_head(&dev->buf_writers);
DRM_DEBUG("\n");
/*
* The kernel's context could be created here, but is now created
* in drm_dma_enqueue. This is more resource-efficient for
* hardware that does not do DMA, but may mean that
* drm_select_queue fails between the time the interrupt is
* initialized and the time the queues are initialized.
*/
return 0;
}
/**
* Open file.
*
* \param inode device inode
* \param filp file pointer.
* \return zero on success or a negative number on failure.
*
* Searches the DRM device with the same minor number, calls open_helper(), and
* increments the device open count. If the open count was previous at zero,
* i.e., it's the first that the device is open, then calls setup().
*/
int drm_open(struct inode *inode, struct file *filp)
{
struct drm_device *dev = NULL;
int minor_id = iminor(inode);
struct drm_minor *minor;
int retcode = 0;
minor = idr_find(&drm_minors_idr, minor_id);
if (!minor)
return -ENODEV;
if (!(dev = minor->dev))
return -ENODEV;
retcode = drm_open_helper(inode, filp, dev);
if (!retcode) {
atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
spin_lock(&dev->count_lock);
if (!dev->open_count++) {
spin_unlock(&dev->count_lock);
retcode = drm_setup(dev);
goto out;
}
spin_unlock(&dev->count_lock);
}
out:
if (!retcode) {
mutex_lock(&dev->struct_mutex);
if (minor->type == DRM_MINOR_LEGACY) {
if (dev->dev_mapping == NULL)
dev->dev_mapping = inode->i_mapping;
else if (dev->dev_mapping != inode->i_mapping)
retcode = -ENODEV;
}
mutex_unlock(&dev->struct_mutex);
}
return retcode;
}
EXPORT_SYMBOL(drm_open);
/**
* File \c open operation.
*
* \param inode device inode.
* \param filp file pointer.
*
* Puts the dev->fops corresponding to the device minor number into
* \p filp, call the \c open method, and restore the file operations.
*/
int drm_stub_open(struct inode *inode, struct file *filp)
{
struct drm_device *dev = NULL;
struct drm_minor *minor;
int minor_id = iminor(inode);
int err = -ENODEV;
const struct file_operations *old_fops;
DRM_DEBUG("\n");
mutex_lock(&drm_global_mutex);
minor = idr_find(&drm_minors_idr, minor_id);
if (!minor)
goto out;
if (!(dev = minor->dev))
goto out;
old_fops = filp->f_op;
filp->f_op = fops_get(&dev->driver->fops);
if (filp->f_op == NULL) {
filp->f_op = old_fops;
goto out;
}
if (filp->f_op->open && (err = filp->f_op->open(inode, filp))) {
fops_put(filp->f_op);
filp->f_op = fops_get(old_fops);
}
fops_put(old_fops);
out:
mutex_unlock(&drm_global_mutex);
return err;
}
/**
* Check whether DRI will run on this CPU.
*
* \return non-zero if the DRI will run on this CPU, or zero otherwise.
*/
static int drm_cpu_valid(void)
{
#if defined(__i386__)
if (boot_cpu_data.x86 == 3)
return 0; /* No cmpxchg on a 386 */
#endif
#if defined(__sparc__) && !defined(__sparc_v9__)
return 0; /* No cmpxchg before v9 sparc. */
#endif
return 1;
}
/**
* Called whenever a process opens /dev/drm.
*
* \param inode device inode.
* \param filp file pointer.
* \param dev device.
* \return zero on success or a negative number on failure.
*
* Creates and initializes a drm_file structure for the file private data in \p
* filp and add it into the double linked list in \p dev.
*/
static int drm_open_helper(struct inode *inode, struct file *filp,
struct drm_device * dev)
{
int minor_id = iminor(inode);
struct drm_file *priv;
int ret;
if (filp->f_flags & O_EXCL)
return -EBUSY; /* No exclusive opens */
if (!drm_cpu_valid())
return -EINVAL;
DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor_id);
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
filp->private_data = priv;
priv->filp = filp;
priv->uid = current_euid();
priv->pid = task_pid_nr(current);
priv->minor = idr_find(&drm_minors_idr, minor_id);
priv->ioctl_count = 0;
/* for compatibility root is always authenticated */
priv->authenticated = capable(CAP_SYS_ADMIN);
priv->lock_count = 0;
INIT_LIST_HEAD(&priv->lhead);
INIT_LIST_HEAD(&priv->fbs);
INIT_LIST_HEAD(&priv->event_list);
init_waitqueue_head(&priv->event_wait);
priv->event_space = 4096; /* set aside 4k for event buffer */
if (dev->driver->driver_features & DRIVER_GEM)
drm_gem_open(dev, priv);
if (dev->driver->open) {
ret = dev->driver->open(dev, priv);
if (ret < 0)
goto out_free;
}
/* if there is no current master make this fd it */
mutex_lock(&dev->struct_mutex);
if (!priv->minor->master) {
/* create a new master */
priv->minor->master = drm_master_create(priv->minor);
if (!priv->minor->master) {
mutex_unlock(&dev->struct_mutex);
ret = -ENOMEM;
goto out_free;
}
priv->is_master = 1;
/* take another reference for the copy in the local file priv */
priv->master = drm_master_get(priv->minor->master);
priv->authenticated = 1;
mutex_unlock(&dev->struct_mutex);
if (dev->driver->master_create) {
ret = dev->driver->master_create(dev, priv->master);
if (ret) {
mutex_lock(&dev->struct_mutex);
/* drop both references if this fails */
drm_master_put(&priv->minor->master);
drm_master_put(&priv->master);
mutex_unlock(&dev->struct_mutex);
goto out_free;
}
}
mutex_lock(&dev->struct_mutex);
if (dev->driver->master_set) {
ret = dev->driver->master_set(dev, priv, true);
if (ret) {
/* drop both references if this fails */
drm_master_put(&priv->minor->master);
drm_master_put(&priv->master);
mutex_unlock(&dev->struct_mutex);
goto out_free;
}
}
mutex_unlock(&dev->struct_mutex);
} else {
/* get a reference to the master */
priv->master = drm_master_get(priv->minor->master);
mutex_unlock(&dev->struct_mutex);
}
mutex_lock(&dev->struct_mutex);
list_add(&priv->lhead, &dev->filelist);
mutex_unlock(&dev->struct_mutex);
#ifdef __alpha__
/*
* Default the hose
*/
if (!dev->hose) {
struct pci_dev *pci_dev;
pci_dev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, NULL);
if (pci_dev) {
dev->hose = pci_dev->sysdata;
pci_dev_put(pci_dev);
}
if (!dev->hose) {
struct pci_bus *b = pci_bus_b(pci_root_buses.next);
if (b)
dev->hose = b->sysdata;
}
}
#endif
return 0;
out_free:
kfree(priv);
filp->private_data = NULL;
return ret;
}
/** No-op. */
int drm_fasync(int fd, struct file *filp, int on)
{
struct drm_file *priv = filp->private_data;
struct drm_device *dev = priv->minor->dev;
DRM_DEBUG("fd = %d, device = 0x%lx\n", fd,
(long)old_encode_dev(priv->minor->device));
return fasync_helper(fd, filp, on, &dev->buf_async);
}
EXPORT_SYMBOL(drm_fasync);
/*
* Reclaim locked buffers; note that this may be a bad idea if the current
* context doesn't have the hw lock...
*/
static void drm_reclaim_locked_buffers(struct drm_device *dev, struct file *f)
{
struct drm_file *file_priv = f->private_data;
if (drm_i_have_hw_lock(dev, file_priv)) {
dev->driver->reclaim_buffers_locked(dev, file_priv);
} else {
unsigned long _end = jiffies + 3 * DRM_HZ;
int locked = 0;
drm_idlelock_take(&file_priv->master->lock);
/*
* Wait for a while.
*/
do {
spin_lock_bh(&file_priv->master->lock.spinlock);
locked = file_priv->master->lock.idle_has_lock;
spin_unlock_bh(&file_priv->master->lock.spinlock);
if (locked)
break;
schedule();
} while (!time_after_eq(jiffies, _end));
if (!locked) {
DRM_ERROR("reclaim_buffers_locked() deadlock. Please rework this\n"
"\tdriver to use reclaim_buffers_idlelocked() instead.\n"
"\tI will go on reclaiming the buffers anyway.\n");
}
dev->driver->reclaim_buffers_locked(dev, file_priv);
drm_idlelock_release(&file_priv->master->lock);
}
}
static void drm_master_release(struct drm_device *dev, struct file *filp)
{
struct drm_file *file_priv = filp->private_data;
if (dev->driver->reclaim_buffers_locked &&
file_priv->master->lock.hw_lock)
drm_reclaim_locked_buffers(dev, filp);
if (dev->driver->reclaim_buffers_idlelocked &&
file_priv->master->lock.hw_lock) {
drm_idlelock_take(&file_priv->master->lock);
dev->driver->reclaim_buffers_idlelocked(dev, file_priv);
drm_idlelock_release(&file_priv->master->lock);
}
if (drm_i_have_hw_lock(dev, file_priv)) {
DRM_DEBUG("File %p released, freeing lock for context %d\n",
filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
drm_lock_free(&file_priv->master->lock,
_DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
}
if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
!dev->driver->reclaim_buffers_locked) {
dev->driver->reclaim_buffers(dev, file_priv);
}
}
static void drm_events_release(struct drm_file *file_priv)
{
struct drm_device *dev = file_priv->minor->dev;
struct drm_pending_event *e, *et;
struct drm_pending_vblank_event *v, *vt;
unsigned long flags;
spin_lock_irqsave(&dev->event_lock, flags);
/* Remove pending flips */
list_for_each_entry_safe(v, vt, &dev->vblank_event_list, base.link)
if (v->base.file_priv == file_priv) {
list_del(&v->base.link);
drm_vblank_put(dev, v->pipe);
v->base.destroy(&v->base);
}
/* Remove unconsumed events */
list_for_each_entry_safe(e, et, &file_priv->event_list, link)
e->destroy(e);
spin_unlock_irqrestore(&dev->event_lock, flags);
}
/**
* Release file.
*
* \param inode device inode
* \param file_priv DRM file private.
* \return zero on success or a negative number on failure.
*
* If the hardware lock is held then free it, and take it again for the kernel
* context since it's necessary to reclaim buffers. Unlink the file private
* data from its list and free it. Decreases the open count and if it reaches
* zero calls drm_lastclose().
*/
int drm_release(struct inode *inode, struct file *filp)
{
struct drm_file *file_priv = filp->private_data;
struct drm_device *dev = file_priv->minor->dev;
int retcode = 0;
mutex_lock(&drm_global_mutex);
DRM_DEBUG("open_count = %d\n", dev->open_count);
if (dev->driver->preclose)
dev->driver->preclose(dev, file_priv);
/* ========================================================
* Begin inline drm_release
*/
DRM_DEBUG("pid = %d, device = 0x%lx, open_count = %d\n",
task_pid_nr(current),
(long)old_encode_dev(file_priv->minor->device),
dev->open_count);
/* if the master has gone away we can't do anything with the lock */
if (file_priv->minor->master)
drm_master_release(dev, filp);
drm_events_release(file_priv);
if (dev->driver->driver_features & DRIVER_GEM)
drm_gem_release(dev, file_priv);
if (dev->driver->driver_features & DRIVER_MODESET)
drm_fb_release(file_priv);
mutex_lock(&dev->ctxlist_mutex);
if (!list_empty(&dev->ctxlist)) {
struct drm_ctx_list *pos, *n;
list_for_each_entry_safe(pos, n, &dev->ctxlist, head) {
if (pos->tag == file_priv &&
pos->handle != DRM_KERNEL_CONTEXT) {
if (dev->driver->context_dtor)
dev->driver->context_dtor(dev,
pos->handle);
drm_ctxbitmap_free(dev, pos->handle);
list_del(&pos->head);
kfree(pos);
--dev->ctx_count;
}
}
}
mutex_unlock(&dev->ctxlist_mutex);
mutex_lock(&dev->struct_mutex);
if (file_priv->is_master) {
struct drm_master *master = file_priv->master;
struct drm_file *temp;
list_for_each_entry(temp, &dev->filelist, lhead) {
if ((temp->master == file_priv->master) &&
(temp != file_priv))
temp->authenticated = 0;
}
/**
* Since the master is disappearing, so is the
* possibility to lock.
*/
if (master->lock.hw_lock) {
if (dev->sigdata.lock == master->lock.hw_lock)
dev->sigdata.lock = NULL;
master->lock.hw_lock = NULL;
master->lock.file_priv = NULL;
wake_up_interruptible_all(&master->lock.lock_queue);
}
if (file_priv->minor->master == file_priv->master) {
/* drop the reference held my the minor */
if (dev->driver->master_drop)
dev->driver->master_drop(dev, file_priv, true);
drm_master_put(&file_priv->minor->master);
}
}
/* drop the reference held my the file priv */
drm_master_put(&file_priv->master);
file_priv->is_master = 0;
list_del(&file_priv->lhead);
mutex_unlock(&dev->struct_mutex);
if (dev->driver->postclose)
dev->driver->postclose(dev, file_priv);
kfree(file_priv);
/* ========================================================
* End inline drm_release
*/
atomic_inc(&dev->counts[_DRM_STAT_CLOSES]);
spin_lock(&dev->count_lock);
if (!--dev->open_count) {
if (atomic_read(&dev->ioctl_count)) {
DRM_ERROR("Device busy: %d\n",
atomic_read(&dev->ioctl_count));
retcode = -EBUSY;
goto out;
}
retcode = drm_lastclose(dev);
}
out:
spin_unlock(&dev->count_lock);
mutex_unlock(&drm_global_mutex);
return retcode;
}
EXPORT_SYMBOL(drm_release);
static bool
drm_dequeue_event(struct drm_file *file_priv,
size_t total, size_t max, struct drm_pending_event **out)
{
struct drm_device *dev = file_priv->minor->dev;
struct drm_pending_event *e;
unsigned long flags;
bool ret = false;
spin_lock_irqsave(&dev->event_lock, flags);
*out = NULL;
if (list_empty(&file_priv->event_list))
goto out;
e = list_first_entry(&file_priv->event_list,
struct drm_pending_event, link);
if (e->event->length + total > max)
goto out;
file_priv->event_space += e->event->length;
list_del(&e->link);
*out = e;
ret = true;
out:
spin_unlock_irqrestore(&dev->event_lock, flags);
return ret;
}
ssize_t drm_read(struct file *filp, char __user *buffer,
size_t count, loff_t *offset)
{
struct drm_file *file_priv = filp->private_data;
struct drm_pending_event *e;
size_t total;
ssize_t ret;
ret = wait_event_interruptible(file_priv->event_wait,
!list_empty(&file_priv->event_list));
if (ret < 0)
return ret;
total = 0;
while (drm_dequeue_event(file_priv, total, count, &e)) {
if (copy_to_user(buffer + total,
e->event, e->event->length)) {
total = -EFAULT;
break;
}
total += e->event->length;
e->destroy(e);
}
return total;
}
EXPORT_SYMBOL(drm_read);
unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait)
{
struct drm_file *file_priv = filp->private_data;
unsigned int mask = 0;
poll_wait(filp, &file_priv->event_wait, wait);
if (!list_empty(&file_priv->event_list))
mask |= POLLIN | POLLRDNORM;
return mask;
}
EXPORT_SYMBOL(drm_poll);