On Mon Jun 29 11:30:49 2026 +0000, Ricardo Ribalda wrote:
> Split out the wait function, and introduce some new toys: guard and
> lockdep.
>
> This fixes the following cocci warnings:
> drivers/media/dvb-core/dvb_frontend.c:2897:1-7: preceding lock on line 2776
> drivers/media/dvb-core/dvb_frontend.c:2897:1-7: preceding lock on line 2786
> drivers/media/dvb-core/dvb_frontend.c:2897:1-7: preceding lock on line 2809
>
> Signed-off-by: Ricardo Ribalda <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/dvb-core/dvb_frontend.c | 58 ++++++++++++++++++++++-------------
1 file changed, 37 insertions(+), 21 deletions(-)
---
diff --git a/drivers/media/dvb-core/dvb_frontend.c
b/drivers/media/dvb-core/dvb_frontend.c
index d99b0348df54..791834e088b6 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -30,6 +30,7 @@
#include <linux/kthread.h>
#include <linux/ktime.h>
#include <linux/compat.h>
+#include <linux/lockdep.h>
#include <asm/processor.h>
#include <media/dvb_frontend.h>
@@ -2841,6 +2842,34 @@ err1:
return ret;
}
+static int wait_dvb_frontend(struct dvb_adapter *adapter,
+ struct dvb_device *mfedev)
+{
+ struct dvb_frontend *mfe = mfedev->priv;
+ struct dvb_frontend_private *mfepriv = mfe->frontend_priv;
+ int mferetry = (dvb_mfe_wait_time << 1);
+ int ret = 0;
+
+ lockdep_assert_held(&adapter->mfe_lock);
+
+ if (mfedev->users == -1 && !mfepriv->thread)
+ return 0;
+
+ mutex_unlock(&adapter->mfe_lock);
+
+ while (mferetry-- && (mfedev->users != -1 || mfepriv->thread)) {
+ if (msleep_interruptible(500))
+ if (signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
+ }
+
+ mutex_lock(&adapter->mfe_lock);
+
+ return ret;
+}
+
static int dvb_frontend_open(struct inode *inode, struct file *file)
{
struct dvb_device *dvbdev = file->private_data;
@@ -2855,19 +2884,16 @@ static int dvb_frontend_open(struct inode *inode,
struct file *file)
if (!adapter->mfe_shared)
return __dvb_frontend_open(inode, file);
+ guard(mutex)(&adapter->mfe_lock);
+
if (adapter->mfe_shared == 2) {
- mutex_lock(&adapter->mfe_lock);
if ((file->f_flags & O_ACCMODE) != O_RDONLY) {
if (adapter->mfe_dvbdev &&
- !adapter->mfe_dvbdev->writers) {
- mutex_unlock(&adapter->mfe_lock);
+ !adapter->mfe_dvbdev->writers)
return -EBUSY;
- }
adapter->mfe_dvbdev = dvbdev;
}
} else {
- mutex_lock(&adapter->mfe_lock);
-
if (!adapter->mfe_dvbdev) {
adapter->mfe_dvbdev = dvbdev;
} else if (adapter->mfe_dvbdev != dvbdev) {
@@ -2877,34 +2903,24 @@ static int dvb_frontend_open(struct inode *inode,
struct file *file)
*mfe = mfedev->priv;
struct dvb_frontend_private
*mfepriv = mfe->frontend_priv;
- int mferetry = (dvb_mfe_wait_time << 1);
-
- mutex_unlock(&adapter->mfe_lock);
- while (mferetry-- && (mfedev->users != -1 ||
- mfepriv->thread)) {
- if (msleep_interruptible(500)) {
- if (signal_pending(current))
- return -EINTR;
- }
- }
- mutex_lock(&adapter->mfe_lock);
+ ret = wait_dvb_frontend(adapter, mfedev);
+ if (ret)
+ return ret;
+
if (adapter->mfe_dvbdev != dvbdev) {
mfedev = adapter->mfe_dvbdev;
mfe = mfedev->priv;
mfepriv = mfe->frontend_priv;
if (mfedev->users != -1 ||
- mfepriv->thread) {
- mutex_unlock(&adapter->mfe_lock);
+ mfepriv->thread)
return -EBUSY;
- }
adapter->mfe_dvbdev = dvbdev;
}
}
}
ret = __dvb_frontend_open(inode, file);
- mutex_unlock(&adapter->mfe_lock);
return ret;
}
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