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28 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
33 * This file implements a simple replacement for the buffer manager use
34 * of the DRM heavyweight hardware lock.
35 * The lock is a read-write lock. Taking it in read mode and write mode
36 * is relatively fast, and intended for in-kernel use only.
38 * The vt mode is used only when there is a need to block all
39 * user-space processes from validating buffers.
40 * It's allowed to leave kernel space with the vt lock held.
41 * If a user-space process dies while having the vt-lock,
42 * it will be released during the file descriptor release. The vt lock
43 * excludes write lock and read lock.
45 * The suspend mode is used to lock out all TTM users when preparing for
46 * and executing suspend operations.
53 #include <dev/drm2/drmP.h>
54 #include <dev/drm2/drm.h>
55 #include <dev/drm2/ttm/ttm_object.h>
60 * @base: ttm base object used solely to release the lock if the client
61 * holding the lock dies.
62 * @queue: Queue for processes waiting for lock change-of-status.
63 * @lock: Spinlock protecting some lock members.
64 * @rw: Read-write lock counter. Protected by @lock.
65 * @flags: Lock state. Protected by @lock.
66 * @kill_takers: Boolean whether to kill takers of the lock.
67 * @signal: Signal to send when kill_takers is true.
71 struct ttm_base_object base;
77 struct ttm_object_file *vt_holder;
84 * @lock: Pointer to a struct ttm_lock
85 * Initializes the lock.
87 extern void ttm_lock_init(struct ttm_lock *lock);
92 * @lock: Pointer to a struct ttm_lock
94 * Releases a read lock.
96 extern void ttm_read_unlock(struct ttm_lock *lock);
101 * @lock: Pointer to a struct ttm_lock
102 * @interruptible: Interruptible sleeping while waiting for a lock.
104 * Takes the lock in read mode.
106 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
108 extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible);
113 * @lock: Pointer to a struct ttm_lock
114 * @interruptible: Interruptible sleeping while waiting for a lock.
116 * Tries to take the lock in read mode. If the lock is already held
117 * in write mode, the function will return -EBUSY. If the lock is held
118 * in vt or suspend mode, the function will sleep until these modes
122 * -EBUSY The lock was already held in write mode.
123 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
125 extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible);
130 * @lock: Pointer to a struct ttm_lock
132 * Downgrades a write lock to a read lock.
134 extern void ttm_lock_downgrade(struct ttm_lock *lock);
139 * @lock: Pointer to a struct ttm_lock
141 * Takes the lock in suspend mode. Excludes read and write mode.
143 extern void ttm_suspend_lock(struct ttm_lock *lock);
148 * @lock: Pointer to a struct ttm_lock
150 * Releases a suspend lock
152 extern void ttm_suspend_unlock(struct ttm_lock *lock);
157 * @lock: Pointer to a struct ttm_lock
158 * @interruptible: Interruptible sleeping while waiting for a lock.
159 * @tfile: Pointer to a struct ttm_object_file to register the lock with.
161 * Takes the lock in vt mode.
163 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
164 * -ENOMEM: Out of memory when locking.
166 extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible,
167 struct ttm_object_file *tfile);
172 * @lock: Pointer to a struct ttm_lock
174 * Releases a vt lock.
176 * -EINVAL If the lock was not held.
178 extern int ttm_vt_unlock(struct ttm_lock *lock);
183 * @lock: Pointer to a struct ttm_lock
185 * Releases a write lock.
187 extern void ttm_write_unlock(struct ttm_lock *lock);
192 * @lock: Pointer to a struct ttm_lock
193 * @interruptible: Interruptible sleeping while waiting for a lock.
195 * Takes the lock in write mode.
197 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
199 extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
201 void ttm_write_lock_downgrade(struct ttm_lock *lock);
206 * @lock: Pointer to a struct ttm_lock
207 * @val: Boolean whether to kill processes taking the lock.
208 * @signal: Signal to send to the process taking the lock.
210 * The kill-when-taking-lock functionality is used to kill processes that keep
211 * on using the TTM functionality when its resources has been taken down, for
212 * example when the X server exits. A typical sequence would look like this:
213 * - X server takes lock in write mode.
214 * - ttm_lock_set_kill() is called with @val set to true.
215 * - As part of X server exit, TTM resources are taken down.
216 * - X server releases the lock on file release.
217 * - Another dri client wants to render, takes the lock and is killed.
220 static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val,
223 lock->kill_takers = val;
225 lock->signal = signal;