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| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-02-04 18:01:45 +0300 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-02-11 17:03:09 +0300 |
| commit | 591a2abf149f6fa14807992eca60c9ee359f114d (patch) | |
| tree | cb41b20f2ac22b7f3a713004753c145b0a808e9a /drivers/gpu/drm/drm_file.c | |
| parent | c368ec194dd0e86e7516bc61ae1df584dec73e90 (diff) | |
| download | linux-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.c | 6 |
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; } |