drm/ttm: Add ttm lock functionality.

This is intended to be used by ttm-aware drivers to
1) Block clients to inactive masters when
they try to validate buffers for GPU use.
2) Optionally block clients to the current master when
there is thrashing due to GPU memory shortage.

Used by the vmwgfx driver.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 312 insertions, 1 deletions

diff --git a/drivers/gpu/drm/ttm/Makefile b/drivers/gpu/drm/ttm/Makefile
index a9cc9f89536..4473549bc5d 100644
--- a/drivers/gpu/drm/ttm/Makefile
+++ b/drivers/gpu/drm/ttm/Makefile
@@ -4,6 +4,6 @@
 ccflags-y := -Iinclude/drm
 ttm-y := ttm_agp_backend.o ttm_memory.o ttm_tt.o ttm_bo.o \
 	ttm_bo_util.o ttm_bo_vm.o ttm_module.o ttm_global.o \
-	ttm_object.o
+	ttm_object.o ttm_lock.o
 
 obj-$(CONFIG_DRM_TTM) += ttm.o
diff --git a/drivers/gpu/drm/ttm/ttm_lock.c b/drivers/gpu/drm/ttm/ttm_lock.c
new file mode 100644
index 00000000000..f619ebcaa4e
--- /dev/null
+++ b/drivers/gpu/drm/ttm/ttm_lock.c
@@ -0,0 +1,311 @@
+/**************************************************************************
+ *
+ * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
+ * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS 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: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
+ */
+
+#include "ttm/ttm_lock.h"
+#include "ttm/ttm_module.h"
+#include <asm/atomic.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+
+#define TTM_WRITE_LOCK_PENDING    (1 << 0)
+#define TTM_VT_LOCK_PENDING       (1 << 1)
+#define TTM_SUSPEND_LOCK_PENDING  (1 << 2)
+#define TTM_VT_LOCK               (1 << 3)
+#define TTM_SUSPEND_LOCK          (1 << 4)
+
+void ttm_lock_init(struct ttm_lock *lock)
+{
+	spin_lock_init(&lock->lock);
+	init_waitqueue_head(&lock->queue);
+	lock->rw = 0;
+	lock->flags = 0;
+	lock->kill_takers = false;
+	lock->signal = SIGKILL;
+}
+EXPORT_SYMBOL(ttm_lock_init);
+
+void ttm_read_unlock(struct ttm_lock *lock)
+{
+	spin_lock(&lock->lock);
+	if (--lock->rw == 0)
+		wake_up_all(&lock->queue);
+	spin_unlock(&lock->lock);
+}
+EXPORT_SYMBOL(ttm_read_unlock);
+
+static bool __ttm_read_lock(struct ttm_lock *lock)
+{
+	bool locked = false;
+
+	spin_lock(&lock->lock);
+	if (unlikely(lock->kill_takers)) {
+		send_sig(lock->signal, current, 0);
+		spin_unlock(&lock->lock);
+		return false;
+	}
+	if (lock->rw >= 0 && lock->flags == 0) {
+		++lock->rw;
+		locked = true;
+	}
+	spin_unlock(&lock->lock);
+	return locked;
+}
+
+int ttm_read_lock(struct ttm_lock *lock, bool interruptible)
+{
+	int ret = 0;
+
+	if (interruptible)
+		ret = wait_event_interruptible(lock->queue,
+					       __ttm_read_lock(lock));
+	else
+		wait_event(lock->queue, __ttm_read_lock(lock));
+	return ret;
+}
+EXPORT_SYMBOL(ttm_read_lock);
+
+static bool __ttm_read_trylock(struct ttm_lock *lock, bool *locked)
+{
+	bool block = true;
+
+	*locked = false;
+
+	spin_lock(&lock->lock);
+	if (unlikely(lock->kill_takers)) {
+		send_sig(lock->signal, current, 0);
+		spin_unlock(&lock->lock);
+		return false;
+	}
+	if (lock->rw >= 0 && lock->flags == 0) {
+		++lock->rw;
+		block = false;
+		*locked = true;
+	} else if (lock->flags == 0) {
+		block = false;
+	}
+	spin_unlock(&lock->lock);
+
+	return !block;
+}
+
+int ttm_read_trylock(struct ttm_lock *lock, bool interruptible)
+{
+	int ret = 0;
+	bool locked;
+
+	if (interruptible)
+		ret = wait_event_interruptible
+			(lock->queue, __ttm_read_trylock(lock, &locked));
+	else
+		wait_event(lock->queue, __ttm_read_trylock(lock, &locked));
+
+	if (unlikely(ret != 0)) {
+		BUG_ON(locked);
+		return ret;
+	}
+
+	return (locked) ? 0 : -EBUSY;
+}
+
+void ttm_write_unlock(struct ttm_lock *lock)
+{
+	spin_lock(&lock->lock);
+	lock->rw = 0;
+	wake_up_all(&lock->queue);
+	spin_unlock(&lock->lock);
+}
+EXPORT_SYMBOL(ttm_write_unlock);
+
+static bool __ttm_write_lock(struct ttm_lock *lock)
+{
+	bool locked = false;
+
+	spin_lock(&lock->lock);
+	if (unlikely(lock->kill_takers)) {
+		send_sig(lock->signal, current, 0);
+		spin_unlock(&lock->lock);
+		return false;
+	}
+	if (lock->rw == 0 && ((lock->flags & ~TTM_WRITE_LOCK_PENDING) == 0)) {
+		lock->rw = -1;
+		lock->flags &= ~TTM_WRITE_LOCK_PENDING;
+		locked = true;
+	} else {
+		lock->flags |= TTM_WRITE_LOCK_PENDING;
+	}
+	spin_unlock(&lock->lock);
+	return locked;
+}
+
+int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
+{
+	int ret = 0;
+
+	if (interruptible) {
+		ret = wait_event_interruptible(lock->queue,
+					       __ttm_write_lock(lock));
+		if (unlikely(ret != 0)) {
+			spin_lock(&lock->lock);
+			lock->flags &= ~TTM_WRITE_LOCK_PENDING;
+			wake_up_all(&lock->queue);
+			spin_unlock(&lock->lock);
+		}
+	} else
+		wait_event(lock->queue, __ttm_read_lock(lock));
+
+	return ret;
+}
+EXPORT_SYMBOL(ttm_write_lock);
+
+void ttm_write_lock_downgrade(struct ttm_lock *lock)
+{
+	spin_lock(&lock->lock);
+	lock->rw = 1;
+	wake_up_all(&lock->queue);
+	spin_unlock(&lock->lock);
+}
+
+static int __ttm_vt_unlock(struct ttm_lock *lock)
+{
+	int ret = 0;
+
+	spin_lock(&lock->lock);
+	if (unlikely(!(lock->flags & TTM_VT_LOCK)))
+		ret = -EINVAL;
+	lock->flags &= ~TTM_VT_LOCK;
+	wake_up_all(&lock->queue);
+	spin_unlock(&lock->lock);
+	printk(KERN_INFO TTM_PFX "vt unlock.\n");
+
+	return ret;
+}
+
+static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
+{
+	struct ttm_base_object *base = *p_base;
+	struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
+	int ret;
+
+	*p_base = NULL;
+	ret = __ttm_vt_unlock(lock);
+	BUG_ON(ret != 0);
+}
+
+static bool __ttm_vt_lock(struct ttm_lock *lock)
+{
+	bool locked = false;
+
+	spin_lock(&lock->lock);
+	if (lock->rw == 0) {
+		lock->flags &= ~TTM_VT_LOCK_PENDING;
+		lock->flags |= TTM_VT_LOCK;
+		locked = true;
+	} else {
+		lock->flags |= TTM_VT_LOCK_PENDING;
+	}
+	spin_unlock(&lock->lock);
+	return locked;
+}
+
+int ttm_vt_lock(struct ttm_lock *lock,
+		bool interruptible,
+		struct ttm_object_file *tfile)
+{
+	int ret = 0;
+
+	if (interruptible) {
+		ret = wait_event_interruptible(lock->queue,
+					       __ttm_vt_lock(lock));
+		if (unlikely(ret != 0)) {
+			spin_lock(&lock->lock);
+			lock->flags &= ~TTM_VT_LOCK_PENDING;
+			wake_up_all(&lock->queue);
+			spin_unlock(&lock->lock);
+			return ret;
+		}
+	} else
+		wait_event(lock->queue, __ttm_vt_lock(lock));
+
+	/*
+	 * Add a base-object, the destructor of which will
+	 * make sure the lock is released if the client dies
+	 * while holding it.
+	 */
+
+	ret = ttm_base_object_init(tfile, &lock->base, false,
+				   ttm_lock_type, &ttm_vt_lock_remove, NULL);
+	if (ret)
+		(void)__ttm_vt_unlock(lock);
+	else {
+		lock->vt_holder = tfile;
+		printk(KERN_INFO TTM_PFX "vt lock.\n");
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(ttm_vt_lock);
+
+int ttm_vt_unlock(struct ttm_lock *lock)
+{
+	return ttm_ref_object_base_unref(lock->vt_holder,
+					 lock->base.hash.key, TTM_REF_USAGE);
+}
+EXPORT_SYMBOL(ttm_vt_unlock);
+
+void ttm_suspend_unlock(struct ttm_lock *lock)
+{
+	spin_lock(&lock->lock);
+	lock->flags &= ~TTM_SUSPEND_LOCK;
+	wake_up_all(&lock->queue);
+	spin_unlock(&lock->lock);
+}
+
+static bool __ttm_suspend_lock(struct ttm_lock *lock)
+{
+	bool locked = false;
+
+	spin_lock(&lock->lock);
+	if (lock->rw == 0) {
+		lock->flags &= ~TTM_SUSPEND_LOCK_PENDING;
+		lock->flags |= TTM_SUSPEND_LOCK;
+		locked = true;
+	} else {
+		lock->flags |= TTM_SUSPEND_LOCK_PENDING;
+	}
+	spin_unlock(&lock->lock);
+	return locked;
+}
+
+void ttm_suspend_lock(struct ttm_lock *lock)
+{
+	wait_event(lock->queue, __ttm_suspend_lock(lock));
+}