From 7a2c65dd32b1cfa8bae55250dfdfe3d049e2f336 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 24 Jan 2020 12:56:26 +0000 Subject: drm: Release filp before global lock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The file is not part of the global drm resource and can be released prior to take the global mutex to drop the open_count (and potentially close) the drm device. As the global mutex is indeed global, not only within the device but across devices, a slow file release mechanism can bottleneck the entire system. However, inside drm_close_helper() there are a number of dev->driver callbacks that take the drm_device as the first parameter... Worryingly some of those callbacks may be (implicitly) depending on the global mutex. v2: Drop the debug message for the open-count, it's included with the drm_file_free() debug message -- and for good measure make that up as reading outside of the mutex. v3: Separate the calling of the filp cleanup outside of drm_global_mutex into a new drm_release_noglobal() hook, so that we can phase the transition. drm/savage relies on the global mutex, and there may be more, so be cautious. Signed-off-by: Chris Wilson Cc: Thomas Hellström (VMware) Reviewed-by: Thomas Hellström (VMware) Link: https://patchwork.freedesktop.org/patch/msgid/20200124125627.125042-1-chris@chris-wilson.co.uk --- include/drm/drm_file.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h index 8b099b347817..19df8028a6c4 100644 --- a/include/drm/drm_file.h +++ b/include/drm/drm_file.h @@ -374,6 +374,7 @@ int drm_open(struct inode *inode, struct file *filp); ssize_t drm_read(struct file *filp, char __user *buffer, size_t count, loff_t *offset); int drm_release(struct inode *inode, struct file *filp); +int drm_release_noglobal(struct inode *inode, struct file *filp); __poll_t drm_poll(struct file *filp, struct poll_table_struct *wait); int drm_event_reserve_init_locked(struct drm_device *dev, struct drm_file *file_priv, -- cgit v1.2.3