From 3f04e0a6cfebf48152ac64502346cdc258811f79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Fri, 8 Feb 2019 15:01:02 +0100
Subject: [PATCH] drm: Fix drm_release() and device unplug
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Git-commit: 3f04e0a6cfebf48152ac64502346cdc258811f79
Patch-mainline: v5.1-rc3
References: bsc#1111666
If userspace has open fd(s) when drm_dev_unplug() is run, it will result
in drm_dev_unregister() being called twice. First in drm_dev_unplug() and
then later in drm_release() through the call to drm_put_dev().
Since userspace already holds a ref on drm_device through the drm_minor,
it's not necessary to add extra ref counting based on no open file
handles. Instead just drm_dev_put() unconditionally in drm_dev_unplug().
We now have this:
- Userpace holds a ref on drm_device as long as there's open fd(s)
- The driver holds a ref on drm_device as long as it's bound to the
struct device
When both sides are done with drm_device, it is released.
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190208140103.28919-2-noralf@tronnes.org
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/drm_drv.c | 6 +-----
drivers/gpu/drm/drm_file.c | 6 ++----
2 files changed, 3 insertions(+), 9 deletions(-)
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -381,11 +381,7 @@ void drm_dev_unplug(struct drm_device *d
synchronize_srcu(&drm_unplug_srcu);
drm_dev_unregister(dev);
-
- mutex_lock(&drm_global_mutex);
- if (dev->open_count == 0)
- drm_dev_put(dev);
- mutex_unlock(&drm_global_mutex);
+ drm_dev_put(dev);
}
EXPORT_SYMBOL(drm_dev_unplug);
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -479,11 +479,9 @@ int drm_release(struct inode *inode, str
drm_file_free(file_priv);
- if (!--dev->open_count) {
+ if (!--dev->open_count)
drm_lastclose(dev);
- if (drm_dev_is_unplugged(dev))
- drm_put_dev(dev);
- }
+
mutex_unlock(&drm_global_mutex);
drm_minor_release(minor);