![Chris Wilson](/assets/img/avatar_default.png)
If the ioctl is not supported on a particular piece of HW/driver combination, report ENOTSUP (aka EOPNOTSUPP) so that it can be easily distinguished from both the lack of the ioctl and from a regular invalid parameter. v2: Across all the kms ioctls we had a mixture of reporting EINVAL, ENODEV and a few ENOTSUPP (most where EINVAL) for a failed drm_core_check_feature(). Update everybody to report ENOTSUPP. v3: ENOTSUPP is an internal errno! It's value (524) does not correspond to a POSIX errno, the one we want is ENOTSUP. However, uapi/asm-generic/errno.h doesn't include ENOTSUP but man errno says "ENOTSUP and EOPNOTSUPP have the same value on Linux, but according to POSIX.1 these error values should be distinct." so use EOPNOTSUPP as its equivalent. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> #v2 Link: https://patchwork.freedesktop.org/patch/msgid/20180913192050.24812-1-chris@chris-wilson.co.uk
350 lines
9.7 KiB
C
350 lines
9.7 KiB
C
/**
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* \file drm_lock.c
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* IOCTLs for locking
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*
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* \author Rickard E. (Rik) Faith <faith@valinux.com>
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* \author Gareth Hughes <gareth@valinux.com>
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*/
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/*
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* Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
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*
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* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
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* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <linux/export.h>
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#include <linux/sched/signal.h>
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#include <drm/drmP.h>
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#include "drm_legacy.h"
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#include "drm_internal.h"
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static int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context);
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/**
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* Take the heavyweight lock.
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*
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* \param lock lock pointer.
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* \param context locking context.
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* \return one if the lock is held, or zero otherwise.
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*
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* Attempt to mark the lock as held by the given context, via the \p cmpxchg instruction.
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*/
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static
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int drm_lock_take(struct drm_lock_data *lock_data,
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unsigned int context)
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{
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unsigned int old, new, prev;
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volatile unsigned int *lock = &lock_data->hw_lock->lock;
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spin_lock_bh(&lock_data->spinlock);
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do {
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old = *lock;
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if (old & _DRM_LOCK_HELD)
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new = old | _DRM_LOCK_CONT;
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else {
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new = context | _DRM_LOCK_HELD |
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((lock_data->user_waiters + lock_data->kernel_waiters > 1) ?
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_DRM_LOCK_CONT : 0);
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}
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prev = cmpxchg(lock, old, new);
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} while (prev != old);
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spin_unlock_bh(&lock_data->spinlock);
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if (_DRM_LOCKING_CONTEXT(old) == context) {
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if (old & _DRM_LOCK_HELD) {
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if (context != DRM_KERNEL_CONTEXT) {
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DRM_ERROR("%d holds heavyweight lock\n",
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context);
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}
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return 0;
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}
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}
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if ((_DRM_LOCKING_CONTEXT(new)) == context && (new & _DRM_LOCK_HELD)) {
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/* Have lock */
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return 1;
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}
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return 0;
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}
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/**
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* This takes a lock forcibly and hands it to context. Should ONLY be used
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* inside *_unlock to give lock to kernel before calling *_dma_schedule.
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*
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* \param dev DRM device.
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* \param lock lock pointer.
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* \param context locking context.
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* \return always one.
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*
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* Resets the lock file pointer.
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* Marks the lock as held by the given context, via the \p cmpxchg instruction.
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*/
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static int drm_lock_transfer(struct drm_lock_data *lock_data,
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unsigned int context)
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{
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unsigned int old, new, prev;
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volatile unsigned int *lock = &lock_data->hw_lock->lock;
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lock_data->file_priv = NULL;
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do {
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old = *lock;
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new = context | _DRM_LOCK_HELD;
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prev = cmpxchg(lock, old, new);
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} while (prev != old);
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return 1;
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}
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static int drm_legacy_lock_free(struct drm_lock_data *lock_data,
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unsigned int context)
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{
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unsigned int old, new, prev;
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volatile unsigned int *lock = &lock_data->hw_lock->lock;
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spin_lock_bh(&lock_data->spinlock);
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if (lock_data->kernel_waiters != 0) {
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drm_lock_transfer(lock_data, 0);
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lock_data->idle_has_lock = 1;
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spin_unlock_bh(&lock_data->spinlock);
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return 1;
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}
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spin_unlock_bh(&lock_data->spinlock);
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do {
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old = *lock;
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new = _DRM_LOCKING_CONTEXT(old);
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prev = cmpxchg(lock, old, new);
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} while (prev != old);
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if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
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DRM_ERROR("%d freed heavyweight lock held by %d\n",
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context, _DRM_LOCKING_CONTEXT(old));
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return 1;
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}
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wake_up_interruptible(&lock_data->lock_queue);
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return 0;
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}
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/**
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* Lock ioctl.
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*
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* \param inode device inode.
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* \param file_priv DRM file private.
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* \param cmd command.
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* \param arg user argument, pointing to a drm_lock structure.
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* \return zero on success or negative number on failure.
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*
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* Add the current task to the lock wait queue, and attempt to take to lock.
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*/
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int drm_legacy_lock(struct drm_device *dev, void *data,
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struct drm_file *file_priv)
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{
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DECLARE_WAITQUEUE(entry, current);
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struct drm_lock *lock = data;
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struct drm_master *master = file_priv->master;
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int ret = 0;
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if (!drm_core_check_feature(dev, DRIVER_LEGACY))
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return -EOPNOTSUPP;
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++file_priv->lock_count;
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if (lock->context == DRM_KERNEL_CONTEXT) {
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DRM_ERROR("Process %d using kernel context %d\n",
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task_pid_nr(current), lock->context);
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return -EINVAL;
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}
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DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
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lock->context, task_pid_nr(current),
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master->lock.hw_lock ? master->lock.hw_lock->lock : -1,
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lock->flags);
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add_wait_queue(&master->lock.lock_queue, &entry);
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spin_lock_bh(&master->lock.spinlock);
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master->lock.user_waiters++;
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spin_unlock_bh(&master->lock.spinlock);
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for (;;) {
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__set_current_state(TASK_INTERRUPTIBLE);
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if (!master->lock.hw_lock) {
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/* Device has been unregistered */
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send_sig(SIGTERM, current, 0);
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ret = -EINTR;
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break;
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}
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if (drm_lock_take(&master->lock, lock->context)) {
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master->lock.file_priv = file_priv;
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master->lock.lock_time = jiffies;
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break; /* Got lock */
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}
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/* Contention */
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mutex_unlock(&drm_global_mutex);
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schedule();
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mutex_lock(&drm_global_mutex);
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if (signal_pending(current)) {
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ret = -EINTR;
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break;
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}
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}
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spin_lock_bh(&master->lock.spinlock);
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master->lock.user_waiters--;
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spin_unlock_bh(&master->lock.spinlock);
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__set_current_state(TASK_RUNNING);
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remove_wait_queue(&master->lock.lock_queue, &entry);
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DRM_DEBUG("%d %s\n", lock->context,
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ret ? "interrupted" : "has lock");
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if (ret) return ret;
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/* don't set the block all signals on the master process for now
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* really probably not the correct answer but lets us debug xkb
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* xserver for now */
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if (!drm_is_current_master(file_priv)) {
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dev->sigdata.context = lock->context;
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dev->sigdata.lock = master->lock.hw_lock;
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}
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if (dev->driver->dma_quiescent && (lock->flags & _DRM_LOCK_QUIESCENT))
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{
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if (dev->driver->dma_quiescent(dev)) {
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DRM_DEBUG("%d waiting for DMA quiescent\n",
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lock->context);
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return -EBUSY;
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}
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}
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return 0;
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}
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/**
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* Unlock ioctl.
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*
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* \param inode device inode.
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* \param file_priv DRM file private.
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* \param cmd command.
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* \param arg user argument, pointing to a drm_lock structure.
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* \return zero on success or negative number on failure.
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*
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* Transfer and free the lock.
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*/
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int drm_legacy_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
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{
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struct drm_lock *lock = data;
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struct drm_master *master = file_priv->master;
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if (!drm_core_check_feature(dev, DRIVER_LEGACY))
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return -EOPNOTSUPP;
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if (lock->context == DRM_KERNEL_CONTEXT) {
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DRM_ERROR("Process %d using kernel context %d\n",
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task_pid_nr(current), lock->context);
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return -EINVAL;
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}
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if (drm_legacy_lock_free(&master->lock, lock->context)) {
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/* FIXME: Should really bail out here. */
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}
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return 0;
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}
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/**
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* This function returns immediately and takes the hw lock
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* with the kernel context if it is free, otherwise it gets the highest priority when and if
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* it is eventually released.
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*
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* This guarantees that the kernel will _eventually_ have the lock _unless_ it is held
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* by a blocked process. (In the latter case an explicit wait for the hardware lock would cause
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* a deadlock, which is why the "idlelock" was invented).
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*
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* This should be sufficient to wait for GPU idle without
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* having to worry about starvation.
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*/
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void drm_legacy_idlelock_take(struct drm_lock_data *lock_data)
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{
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int ret;
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spin_lock_bh(&lock_data->spinlock);
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lock_data->kernel_waiters++;
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if (!lock_data->idle_has_lock) {
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spin_unlock_bh(&lock_data->spinlock);
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ret = drm_lock_take(lock_data, DRM_KERNEL_CONTEXT);
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spin_lock_bh(&lock_data->spinlock);
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if (ret == 1)
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lock_data->idle_has_lock = 1;
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}
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spin_unlock_bh(&lock_data->spinlock);
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}
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EXPORT_SYMBOL(drm_legacy_idlelock_take);
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void drm_legacy_idlelock_release(struct drm_lock_data *lock_data)
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{
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unsigned int old, prev;
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volatile unsigned int *lock = &lock_data->hw_lock->lock;
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spin_lock_bh(&lock_data->spinlock);
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if (--lock_data->kernel_waiters == 0) {
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if (lock_data->idle_has_lock) {
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do {
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old = *lock;
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prev = cmpxchg(lock, old, DRM_KERNEL_CONTEXT);
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} while (prev != old);
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wake_up_interruptible(&lock_data->lock_queue);
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lock_data->idle_has_lock = 0;
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}
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}
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spin_unlock_bh(&lock_data->spinlock);
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}
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EXPORT_SYMBOL(drm_legacy_idlelock_release);
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static int drm_legacy_i_have_hw_lock(struct drm_device *dev,
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struct drm_file *file_priv)
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{
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struct drm_master *master = file_priv->master;
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return (file_priv->lock_count && master->lock.hw_lock &&
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_DRM_LOCK_IS_HELD(master->lock.hw_lock->lock) &&
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master->lock.file_priv == file_priv);
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}
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void drm_legacy_lock_release(struct drm_device *dev, struct file *filp)
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{
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struct drm_file *file_priv = filp->private_data;
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/* if the master has gone away we can't do anything with the lock */
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if (!dev->master)
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return;
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if (drm_legacy_i_have_hw_lock(dev, file_priv)) {
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DRM_DEBUG("File %p released, freeing lock for context %d\n",
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filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
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drm_legacy_lock_free(&file_priv->master->lock,
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_DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
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}
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}
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