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Message-Id: <20210818073824.1560124-6-desmondcheongzx@gmail.com>
Date: Wed, 18 Aug 2021 15:38:20 +0800
From: Desmond Cheong Zhi Xi <desmondcheongzx@...il.com>
To: maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
tzimmermann@...e.de, airlied@...ux.ie, daniel@...ll.ch,
sumit.semwal@...aro.org, christian.koenig@....com, axboe@...nel.dk,
oleg@...hat.com, tglx@...utronix.de, dvyukov@...gle.com,
walter-zh.wu@...iatek.com
Cc: Desmond Cheong Zhi Xi <desmondcheongzx@...il.com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
intel-gfx@...ts.freedesktop.org, linux-media@...r.kernel.org,
linaro-mm-sig@...ts.linaro.org, skhan@...uxfoundation.org,
gregkh@...uxfoundation.org,
linux-kernel-mentees@...ts.linuxfoundation.org
Subject: [PATCH v3 5/9] drm: protect magic_map,unique{_len} with master_lookup_lock
Currently, drm_device.master_mutex is used to serialize writes to the
drm_master.magic_map idr and to protect drm_master.unique{_len}.
In preparation for converting drm_device.master_mutex into an outer
rwsem that might be read locked before entering some of these
functions, we can instead serialize access to drm_master.magic_map and
drm_master.unique{_len} using drm_device.master_lookup_lock which is
an inner lock.
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@...il.com>
---
drivers/gpu/drm/drm_auth.c | 12 +++++++-----
drivers/gpu/drm/drm_ioctl.c | 10 ++++++----
include/drm/drm_auth.h | 6 +++---
include/drm/drm_device.h | 7 ++++++-
4 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index b7230604496b..0acb444fbbac 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -98,10 +98,10 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
struct drm_master *master;
int ret = 0;
- mutex_lock(&dev->master_mutex);
+ spin_lock(&dev->master_lookup_lock);
master = file_priv->master;
if (!master) {
- mutex_unlock(&dev->master_mutex);
+ spin_unlock(&dev->master_lookup_lock);
return -EINVAL;
}
@@ -112,7 +112,7 @@ int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
file_priv->magic = ret;
}
auth->magic = file_priv->magic;
- mutex_unlock(&dev->master_mutex);
+ spin_unlock(&dev->master_lookup_lock);
DRM_DEBUG("%u\n", auth->magic);
@@ -127,13 +127,13 @@ int drm_authmagic(struct drm_device *dev, void *data,
DRM_DEBUG("%u\n", auth->magic);
- mutex_lock(&dev->master_mutex);
+ spin_lock(&dev->master_lookup_lock);
file = idr_find(&file_priv->master->magic_map, auth->magic);
if (file) {
file->authenticated = 1;
idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
}
- mutex_unlock(&dev->master_mutex);
+ spin_unlock(&dev->master_lookup_lock);
return file ? 0 : -EINVAL;
}
@@ -366,8 +366,10 @@ void drm_master_release(struct drm_file *file_priv)
if (!master)
goto unlock;
+ spin_lock(&dev->master_lookup_lock);
if (file_priv->magic)
idr_remove(&master->magic_map, file_priv->magic);
+ spin_unlock(&dev->master_lookup_lock);
if (!drm_is_current_master_locked(file_priv))
goto out;
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 4d029d3061d9..e5c3845b6e62 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -119,21 +119,21 @@ int drm_getunique(struct drm_device *dev, void *data,
struct drm_unique *u = data;
struct drm_master *master;
- mutex_lock(&dev->master_mutex);
+ spin_lock(&dev->master_lookup_lock);
master = file_priv->master;
if (!master) {
- mutex_unlock(&dev->master_mutex);
+ spin_unlock(&dev->master_lookup_lock);
return -EINVAL;
}
if (u->unique_len >= master->unique_len) {
if (copy_to_user(u->unique, master->unique, master->unique_len)) {
- mutex_unlock(&dev->master_mutex);
+ spin_unlock(&dev->master_lookup_lock);
return -EFAULT;
}
}
u->unique_len = master->unique_len;
- mutex_unlock(&dev->master_mutex);
+ spin_unlock(&dev->master_lookup_lock);
return 0;
}
@@ -405,7 +405,9 @@ static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *f
* Version 1.1 includes tying of DRM to specific device
* Version 1.4 has proper PCI domain support
*/
+ spin_lock(&dev->master_lookup_lock);
retcode = drm_set_busid(dev, file_priv);
+ spin_unlock(&dev->master_lookup_lock);
if (retcode)
goto done;
}
diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h
index ba248ca8866f..f5be73153798 100644
--- a/include/drm/drm_auth.h
+++ b/include/drm/drm_auth.h
@@ -67,17 +67,17 @@ struct drm_master {
struct drm_device *dev;
/**
* @unique: Unique identifier: e.g. busid. Protected by
- * &drm_device.master_mutex.
+ * &drm_device.master_lookup_lock.
*/
char *unique;
/**
* @unique_len: Length of unique field. Protected by
- * &drm_device.master_mutex.
+ * &drm_device.master_lookup_lock.
*/
int unique_len;
/**
* @magic_map: Map of used authentication tokens. Protected by
- * &drm_device.master_mutex.
+ * &drm_device.master_lookup_lock.
*/
struct idr magic_map;
void *driver_priv;
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index 506eb2784819..cf5d15aeb25f 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -152,7 +152,12 @@ struct drm_device {
*/
struct mutex master_mutex;
- /** @master_lookup_lock: Serializes &drm_file.master. */
+ /**
+ * @master_lookup_lock:
+ *
+ * Serializes &drm_file.master, &drm_master.magic_map,
+ * &drm_master.unique, and &drm_master.unique_len.
+ */
spinlock_t master_lookup_lock;
/**
--
2.25.1
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