On 08/08/2010 10:37 AM, Chris Wilson wrote:
Dave Airlie:
I might be missing something, but what stops the race with something
reopening while we are in lastclose now?
The global_mutex which appears to fill this role is only taken inside
the drm_stub_open() and not drm_open() itself. As that mutex appears to
serve no other role, retask it to serialise open/lastclose.
Hmm.
But, if used this way, drm_global_mutex needs to protect *all* accesses
to dev::open_count, what is count_clock used for? Can't it be removed?
/Thomas
Signed-off-by: Chris Wilson<ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/drm_fops.c | 35 ++++++++++++++++++-----------------
1 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 6367961..71bcd1b 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -123,27 +123,30 @@ int drm_open(struct inode *inode, struct file *filp)
struct drm_device *dev = NULL;
int minor_id = iminor(inode);
struct drm_minor *minor;
- int retcode = 0;
+ int retcode = -ENODEV;
+ mutex_lock(&drm_global_mutex);
minor = idr_find(&drm_minors_idr, minor_id);
if (!minor)
- return -ENODEV;
+ goto err;
if (!(dev = minor->dev))
- return -ENODEV;
+ goto err;
retcode = drm_open_helper(inode, filp, dev);
- if (!retcode) {
- atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
- spin_lock(&dev->count_lock);
- if (!dev->open_count++) {
- spin_unlock(&dev->count_lock);
- retcode = drm_setup(dev);
- goto out;
- }
+ if (retcode)
+ goto err;
+
+ atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
+ spin_lock(&dev->count_lock);
+ if (!dev->open_count++) {
spin_unlock(&dev->count_lock);
- }
-out:
+ retcode = drm_setup(dev);
+ } else
+ spin_unlock(&dev->count_lock);
+err:
+ mutex_unlock(&drm_global_mutex);
+
if (!retcode) {
mutex_lock(&dev->struct_mutex);
if (minor->type == DRM_MINOR_LEGACY) {
@@ -178,7 +181,6 @@ int drm_stub_open(struct inode *inode, struct file *filp)
DRM_DEBUG("\n");
- mutex_lock(&drm_global_mutex);
minor = idr_find(&drm_minors_idr, minor_id);
if (!minor)
goto out;
@@ -198,8 +200,8 @@ int drm_stub_open(struct inode *inode, struct file *filp)
}
fops_put(old_fops);
+ ret = 0;
out:
- mutex_unlock(&drm_global_mutex);
return err;
}
@@ -474,8 +476,6 @@ int drm_release(struct inode *inode, struct file *filp)
struct drm_device *dev = file_priv->minor->dev;
int retcode = 0;
- mutex_lock(&drm_global_mutex);
-
DRM_DEBUG("open_count = %d\n", dev->open_count);
if (dev->driver->preclose)
@@ -569,6 +569,7 @@ int drm_release(struct inode *inode, struct file *filp)
* End inline drm_release
*/
+ mutex_lock(&drm_global_mutex);
atomic_inc(&dev->counts[_DRM_STAT_CLOSES]);
spin_lock(&dev->count_lock);
if (!--dev->open_count) {
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