diff options
Diffstat (limited to 'include/drm')
| -rw-r--r-- | include/drm/drm_modeset_lock.h | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h index a685d1bb21f2..a308f2d6496f 100644 --- a/include/drm/drm_modeset_lock.h +++ b/include/drm/drm_modeset_lock.h @@ -130,4 +130,63 @@ void drm_warn_on_modeset_not_all_locked(struct drm_device *dev); int drm_modeset_lock_all_ctx(struct drm_device *dev, struct drm_modeset_acquire_ctx *ctx); +/** + * DRM_MODESET_LOCK_ALL_BEGIN - Helper to acquire modeset locks + * @dev: drm device + * @ctx: local modeset acquire context, will be dereferenced + * @flags: DRM_MODESET_ACQUIRE_* flags to pass to drm_modeset_acquire_init() + * @ret: local ret/err/etc variable to track error status + * + * Use these macros to simplify grabbing all modeset locks using a local + * context. This has the advantage of reducing boilerplate, but also properly + * checking return values where appropriate. + * + * Any code run between BEGIN and END will be holding the modeset locks. + * + * This must be paired with DRM_MODESET_LOCK_ALL_END(). We will jump back and + * forth between the labels on deadlock and error conditions. + * + * Drivers can acquire additional modeset locks. If any lock acquisition + * fails, the control flow needs to jump to DRM_MODESET_LOCK_ALL_END() with + * the @ret parameter containing the return value of drm_modeset_lock(). + * + * Returns: + * The only possible value of ret immediately after DRM_MODESET_LOCK_ALL_BEGIN() + * is 0, so no error checking is necessary + */ +#define DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, flags, ret) \ + drm_modeset_acquire_init(&ctx, flags); \ +modeset_lock_retry: \ + ret = drm_modeset_lock_all_ctx(dev, &ctx); \ + if (ret) \ + goto modeset_lock_fail; + +/** + * DRM_MODESET_LOCK_ALL_END - Helper to release and cleanup modeset locks + * @ctx: local modeset acquire context, will be dereferenced + * @ret: local ret/err/etc variable to track error status + * + * The other side of DRM_MODESET_LOCK_ALL_BEGIN(). It will bounce back to BEGIN + * if ret is -EDEADLK. + * + * It's important that you use the same ret variable for begin and end so + * deadlock conditions are properly handled. + * + * Returns: + * ret will be untouched unless it is -EDEADLK on entry. That means that if you + * successfully acquire the locks, ret will be whatever your code sets it to. If + * there is a deadlock or other failure with acquire or backoff, ret will be set + * to that failure. In both of these cases the code between BEGIN/END will not + * be run, so the failure will reflect the inability to grab the locks. + */ +#define DRM_MODESET_LOCK_ALL_END(ctx, ret) \ +modeset_lock_fail: \ + if (ret == -EDEADLK) { \ + ret = drm_modeset_backoff(&ctx); \ + if (!ret) \ + goto modeset_lock_retry; \ + } \ + drm_modeset_drop_locks(&ctx); \ + drm_modeset_acquire_fini(&ctx); + #endif /* DRM_MODESET_LOCK_H_ */ |