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authorDaniel Vetter <daniel.vetter@ffwll.ch>2020-02-04 18:01:45 +0300
committerDaniel Vetter <daniel.vetter@ffwll.ch>2020-02-11 17:03:09 +0300
commit591a2abf149f6fa14807992eca60c9ee359f114d (patch)
treecb41b20f2ac22b7f3a713004753c145b0a808e9a /drivers/gpu/drm/drm_file.c
parentc368ec194dd0e86e7516bc61ae1df584dec73e90 (diff)
downloadlinux-591a2abf149f6fa14807992eca60c9ee359f114d.tar.xz
drm: Push drm_global_mutex locking in drm_open
We want to only take the BKL on crap drivers, but to know whether we have a crap driver we first need to look it up. Split this shuffle out from the main BKL-disabling patch, for more clarity. Historical aside: When the kernel-wide BKL was removed, it was replaced by drm_global_mutex within the scope of the drm subsystem hence why these two things are (almost) interchangeable as concepts here. Since the minors are refcounted drm_minor_acquire is purely internal and this does not have a driver visible effect. v2: Push the locking even further into drm_open(), suggested by Chris. This gives us more symmetry with drm_release(), and maybe a futuer avenue where we make drm_global_mutex locking (partially) opt-in like with drm_release_noglobal(). v3: - Actually push this stuff correctly, don't unlock twice (Chris) - Fix typo on commit message, plus explain why BKL = drm_global_mutex (Sam) Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Tested-by: Thomas Zimmermann <tzimmermann@suse.de> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200204150146.2006481-5-daniel.vetter@ffwll.ch
Diffstat (limited to 'drivers/gpu/drm/drm_file.c')
-rw-r--r--drivers/gpu/drm/drm_file.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index 1075b3a8b5b1..80d556402ab4 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -378,6 +378,8 @@ int drm_open(struct inode *inode, struct file *filp)
if (IS_ERR(minor))
return PTR_ERR(minor);
+ mutex_lock(&drm_global_mutex);
+
dev = minor->dev;
if (!atomic_fetch_inc(&dev->open_count))
need_setup = 1;
@@ -395,10 +397,14 @@ int drm_open(struct inode *inode, struct file *filp)
goto err_undo;
}
}
+
+ mutex_unlock(&drm_global_mutex);
+
return 0;
err_undo:
atomic_dec(&dev->open_count);
+ mutex_unlock(&drm_global_mutex);
drm_minor_release(minor);
return retcode;
}