| Message ID | 20240506-cocci-locks-v1-5-a67952fe5d19@chromium.org |
|---|---|
| State | New |
| Headers | show |
| Series | media: Fix some cocci locks warnings | expand |
On 06/05/2024 23:10, Ricardo Ribalda wrote: > 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 OK, this patch is really hard to review. And since it is refactoring core framework code, I think this might work better if it is reworked. I *think* (not 100% certain) that it is enough to just split off __dvb_frontend_open. The dvb_frontend_open() can then just do: if (!adapter->mfe_shared) return __dvb_frontend_open(inode, file); and after that you can just take the mfe_lock and keep the existing code. While you can introduce the use of guard(), I don't think it is necessary. This keeps the 'get_shared_frontend' code in dvb_frontend_open() rather then splitting it up, but I think this will produce a much more readable patch. Which IMHO is really important for code like this. Regards, Hans > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.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; >
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;
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@chromium.org> --- drivers/media/dvb-core/dvb_frontend.c | 116 ++++++++++++++++++++-------------- 1 file changed, 69 insertions(+), 47 deletions(-)