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Message-Id: <20240506-cocci-locks-v1-5-a67952fe5d19@chromium.org>
Date: Mon, 06 May 2024 21:10:30 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Andy Walls <awalls@...metrocast.net>,
Mauro Carvalho Chehab <mchehab@...nel.org>, Sean Young <sean@...s.org>,
Jarod Wilson <jarod@...hat.com>
Cc: Hans Verkuil <hverkuil-cisco@...all.nl>, linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org, Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH 5/5] media: drivers/media/dvb-core: Refactor
dvb_frontend_open
Move the shared frontend logic to its own function. This allows using
guard() to handle the mfe_lock mutex, and using lockdep asserts.
There is no intended change of behavior in this code.
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@...omium.org>
---
drivers/media/dvb-core/dvb_frontend.c | 116 ++++++++++++++++++++--------------
1 file changed, 69 insertions(+), 47 deletions(-)
diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index 4f78f30b3646..d04a6092f1ba 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>
@@ -2760,66 +2761,70 @@ static __poll_t dvb_frontend_poll(struct file *file, struct poll_table_struct *w
return 0;
}
-static int dvb_frontend_open(struct inode *inode, struct file *file)
+static int dvb_get_shared_frontend(struct dvb_adapter *adapter,
+ struct dvb_device *dvbdev,
+ struct file *file)
{
- struct dvb_device *dvbdev = file->private_data;
- struct dvb_frontend *fe = dvbdev->priv;
- struct dvb_frontend_private *fepriv = fe->frontend_priv;
- struct dvb_adapter *adapter = fe->dvb;
- int ret;
+ struct dvb_device *mfedev;
+ struct dvb_frontend *mfe;
+ struct dvb_frontend_private *mfepriv;
+ int mferetry;
- dev_dbg(fe->dvb->device, "%s:\n", __func__);
- if (fe->exit == DVB_FE_DEVICE_REMOVED)
- return -ENODEV;
+ lockdep_assert_held(&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);
return -EBUSY;
}
adapter->mfe_dvbdev = dvbdev;
}
- } else if (adapter->mfe_shared) {
- mutex_lock(&adapter->mfe_lock);
+ return 0;
+ }
- if (!adapter->mfe_dvbdev)
- adapter->mfe_dvbdev = dvbdev;
+ if (!adapter->mfe_dvbdev) {
+ adapter->mfe_dvbdev = dvbdev;
+ return 0;
+ }
- else if (adapter->mfe_dvbdev != dvbdev) {
- struct dvb_device
- *mfedev = adapter->mfe_dvbdev;
- struct dvb_frontend
- *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;
- }
- }
+ if (adapter->mfe_dvbdev == dvbdev)
+ return 0;
- 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);
- return -EBUSY;
- }
- adapter->mfe_dvbdev = dvbdev;
+ mfedev = adapter->mfe_dvbdev;
+ mfe = mfedev->priv;
+ mfepriv = mfe->frontend_priv;
+ 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)) {
+ mutex_lock(&adapter->mfe_lock);
+ return -EINTR;
}
}
}
+ 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)
+ return -EBUSY;
+ adapter->mfe_dvbdev = dvbdev;
+ }
+
+ return 0;
+}
+
+static int __dvb_frontend_open(struct inode *inode, struct file *file)
+{
+ struct dvb_device *dvbdev = file->private_data;
+ struct dvb_frontend *fe = dvbdev->priv;
+ struct dvb_frontend_private *fepriv = fe->frontend_priv;
+ int ret;
if (dvbdev->users == -1 && fe->ops.ts_bus_ctrl) {
if ((ret = fe->ops.ts_bus_ctrl(fe, 1)) < 0)
@@ -2871,8 +2876,6 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
dvb_frontend_get(fe);
- if (adapter->mfe_shared)
- mutex_unlock(&adapter->mfe_lock);
return ret;
err3:
@@ -2892,11 +2895,30 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
if (dvbdev->users == -1 && fe->ops.ts_bus_ctrl)
fe->ops.ts_bus_ctrl(fe, 0);
err0:
- if (adapter->mfe_shared)
- mutex_unlock(&adapter->mfe_lock);
return ret;
}
+static int dvb_frontend_open(struct inode *inode, struct file *file)
+{
+ struct dvb_device *dvbdev = file->private_data;
+ struct dvb_frontend *fe = dvbdev->priv;
+ struct dvb_adapter *adapter = fe->dvb;
+ int ret;
+
+ dev_dbg(fe->dvb->device, "%s:\n", __func__);
+ if (fe->exit == DVB_FE_DEVICE_REMOVED)
+ return -ENODEV;
+
+ if (!adapter->mfe_shared)
+ return __dvb_frontend_open(inode, file);
+
+ guard(mutex)(&adapter->mfe_lock);
+ ret = dvb_get_shared_frontend(adapter, dvbdev, file);
+ if (ret)
+ return ret;
+ return __dvb_frontend_open(inode, file);
+}
+
static int dvb_frontend_release(struct inode *inode, struct file *file)
{
struct dvb_device *dvbdev = file->private_data;
--
2.45.0.rc1.225.g2a3ae87e7f-goog
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