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media: drivers/media/dvb-core: Refactor dvb_frontend_open locking

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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 <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Ricardo Ribalda
2026-06-29 11:30:49 +00:00
committed by Hans Verkuil
parent e8123c85a6
commit 245019a083
1 changed files with 36 additions and 20 deletions
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56
drivers/media/dvb-core/dvb_frontend.c
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@@ -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 @@ static int __dvb_frontend_open(struct inode *inode, struct file *file)
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;
}
}
ret = wait_dvb_frontend(adapter, mfedev);
if (ret)
return ret;
mutex_lock(&adapter->mfe_lock);
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;
}