On Thu, 24 Sep 2020 11:41:55 +0300 Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> wrote: > The aim of this is to improve a bit the organization of ioctl() calls in > IIO core. Currently the chardev is split across IIO core sub-modules/files. > The main chardev has to be able to handle ioctl() calls, and if we need to > add buffer ioctl() calls, this would complicate things. > > The 'industrialio-core.c' file will provide a 'iio_device_ioctl()' which > will iterate over a list of ioctls registered with the IIO device. These > can be event ioctl() or buffer ioctl() calls, or something else. > > Each ioctl() handler will have to return a IIO_IOCTL_UNHANDLED code (which > is positive 1), if the ioctl() did not handle the call in any. This > eliminates any potential ambiguities about negative error codes, which > should fail the call altogether. > > If any ioctl() returns 0, it was considered that it was serviced > successfully and the loop will exit. > > This change also moves the handling of the IIO_GET_EVENT_FD_IOCTL command > inside 'industrialio-event.c', where this is better suited. > > This patch is a combination of 2 other patches from an older series: > Patch 1: iio: core: add simple centralized mechanism for ioctl() handlers > Link: https://lore.kernel.org/linux-iio/20200427131100.50845-6-alexandru.ardelean@xxxxxxxxxx/ > Patch 2: iio: core: use new common ioctl() mechanism > Link: https://lore.kernel.org/linux-iio/20200427131100.50845-7-alexandru.ardelean@xxxxxxxxxx/ > > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> > --- > > Note: since this is a change to the IIO core, we don't need to put this in > right now; especially if there is a tight schedule, or we are too close to > a merge window. Looks good to me. As you suggest, lets let this one sit on the list for a while though! Jonathan > > drivers/iio/iio_core.h | 15 ++++++++- > drivers/iio/industrialio-core.c | 56 ++++++++++++++++++++++++-------- > drivers/iio/industrialio-event.c | 28 +++++++++++++++- > include/linux/iio/iio-opaque.h | 2 ++ > 4 files changed, 85 insertions(+), 16 deletions(-) > > diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h > index fd9a5f1d5e51..fced02cadcc3 100644 > --- a/drivers/iio/iio_core.h > +++ b/drivers/iio/iio_core.h > @@ -17,6 +17,20 @@ struct iio_dev; > > extern struct device_type iio_device_type; > > +#define IIO_IOCTL_UNHANDLED 1 > +struct iio_ioctl_handler { > + struct list_head entry; > + long (*ioctl)(struct iio_dev *indio_dev, struct file *filp, > + unsigned int cmd, unsigned long arg); > +}; > + > +long iio_device_ioctl(struct iio_dev *indio_dev, struct file *filp, > + unsigned int cmd, unsigned long arg); > + > +void iio_device_ioctl_handler_register(struct iio_dev *indio_dev, > + struct iio_ioctl_handler *h); > +void iio_device_ioctl_handler_unregister(struct iio_ioctl_handler *h); > + > int __iio_add_chan_devattr(const char *postfix, > struct iio_chan_spec const *chan, > ssize_t (*func)(struct device *dev, > @@ -74,7 +88,6 @@ static inline void iio_buffer_wakeup_poll(struct iio_dev *indio_dev) {} > int iio_device_register_eventset(struct iio_dev *indio_dev); > void iio_device_unregister_eventset(struct iio_dev *indio_dev); > void iio_device_wakeup_eventset(struct iio_dev *indio_dev); > -int iio_event_getfd(struct iio_dev *indio_dev); > > struct iio_event_interface; > bool iio_event_enabled(const struct iio_event_interface *ev_int); > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > index 261d3b17edc9..964a0a2d6f8b 100644 > --- a/drivers/iio/industrialio-core.c > +++ b/drivers/iio/industrialio-core.c > @@ -1567,6 +1567,7 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv) > } > dev_set_name(&dev->dev, "iio:device%d", dev->id); > INIT_LIST_HEAD(&iio_dev_opaque->buffer_list); > + INIT_LIST_HEAD(&iio_dev_opaque->ioctl_handlers); > > return dev; > } > @@ -1660,26 +1661,47 @@ static int iio_chrdev_release(struct inode *inode, struct file *filp) > return 0; > } > > -/* Somewhat of a cross file organization violation - ioctls here are actually > - * event related */ > +void iio_device_ioctl_handler_register(struct iio_dev *indio_dev, > + struct iio_ioctl_handler *h) > +{ > + struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); > + > + list_add_tail(&h->entry, &iio_dev_opaque->ioctl_handlers); > +} > + > +void iio_device_ioctl_handler_unregister(struct iio_ioctl_handler *h) > +{ > + list_del(&h->entry); > +} > + > static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > { > struct iio_dev *indio_dev = filp->private_data; > - int __user *ip = (int __user *)arg; > - int fd; > + struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); > + struct iio_ioctl_handler *h; > + int ret = -ENODEV; > + > + mutex_lock(&indio_dev->info_exist_lock); > > + /** > + * The NULL check here is required to prevent crashing when a device > + * is being removed while userspace would still have open file handles > + * to try to access this device. > + */ > if (!indio_dev->info) > - return -ENODEV; > - > - if (cmd == IIO_GET_EVENT_FD_IOCTL) { > - fd = iio_event_getfd(indio_dev); > - if (fd < 0) > - return fd; > - if (copy_to_user(ip, &fd, sizeof(fd))) > - return -EFAULT; > - return 0; > + goto out_unlock; > + > + ret = -EINVAL; > + list_for_each_entry(h, &iio_dev_opaque->ioctl_handlers, entry) { > + ret = h->ioctl(indio_dev, filp, cmd, arg); > + if (ret != IIO_IOCTL_UNHANDLED) > + break; > } > - return -EINVAL; > + > +out_unlock: > + mutex_unlock(&indio_dev->info_exist_lock); > + > + return ret; > } > > static const struct file_operations iio_buffer_fileops = { > @@ -1796,6 +1818,9 @@ EXPORT_SYMBOL(__iio_device_register); > **/ > void iio_device_unregister(struct iio_dev *indio_dev) > { > + struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); > + struct iio_ioctl_handler *h, *t; > + > cdev_device_del(&indio_dev->chrdev, &indio_dev->dev); > > mutex_lock(&indio_dev->info_exist_lock); > @@ -1806,6 +1831,9 @@ void iio_device_unregister(struct iio_dev *indio_dev) > > indio_dev->info = NULL; > > + list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry) > + list_del(&h->entry); > + > iio_device_wakeup_eventset(indio_dev); > iio_buffer_wakeup_poll(indio_dev); > > diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c > index 99ba657b8568..a2de2fd89067 100644 > --- a/drivers/iio/industrialio-event.c > +++ b/drivers/iio/industrialio-event.c > @@ -31,6 +31,7 @@ > * @flags: file operations related flags including busy flag. > * @group: event interface sysfs attribute group > * @read_lock: lock to protect kfifo read operations > + * @@ioctl_handler: handler for event ioctl() calls > */ > struct iio_event_interface { > wait_queue_head_t wait; > @@ -40,6 +41,7 @@ struct iio_event_interface { > unsigned long flags; > struct attribute_group group; > struct mutex read_lock; > + struct iio_ioctl_handler ioctl_handler; > }; > > bool iio_event_enabled(const struct iio_event_interface *ev_int) > @@ -187,7 +189,7 @@ static const struct file_operations iio_event_chrdev_fileops = { > .llseek = noop_llseek, > }; > > -int iio_event_getfd(struct iio_dev *indio_dev) > +static int iio_event_getfd(struct iio_dev *indio_dev) > { > struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); > struct iio_event_interface *ev_int = iio_dev_opaque->event_interface; > @@ -473,6 +475,24 @@ static void iio_setup_ev_int(struct iio_event_interface *ev_int) > mutex_init(&ev_int->read_lock); > } > > +static long iio_event_ioctl(struct iio_dev *indio_dev, struct file *filp, > + unsigned int cmd, unsigned long arg) > +{ > + int __user *ip = (int __user *)arg; > + int fd; > + > + if (cmd == IIO_GET_EVENT_FD_IOCTL) { > + fd = iio_event_getfd(indio_dev); > + if (fd < 0) > + return fd; > + if (copy_to_user(ip, &fd, sizeof(fd))) > + return -EFAULT; > + return 0; > + } > + > + return IIO_IOCTL_UNHANDLED; > +} > + > static const char *iio_event_group_name = "events"; > int iio_device_register_eventset(struct iio_dev *indio_dev) > { > @@ -526,6 +546,10 @@ int iio_device_register_eventset(struct iio_dev *indio_dev) > ev_int->group.attrs[attrn++] = &p->dev_attr.attr; > indio_dev->groups[indio_dev->groupcounter++] = &ev_int->group; > > + ev_int->ioctl_handler.ioctl = iio_event_ioctl; > + iio_device_ioctl_handler_register(&iio_dev_opaque->indio_dev, > + &ev_int->ioctl_handler); > + > return 0; > > error_free_setup_event_lines: > @@ -558,6 +582,8 @@ void iio_device_unregister_eventset(struct iio_dev *indio_dev) > > if (ev_int == NULL) > return; > + > + iio_device_ioctl_handler_unregister(&ev_int->ioctl_handler); > iio_free_chan_devattr_list(&ev_int->dev_attr_list); > kfree(ev_int->group.attrs); > kfree(ev_int); > diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h > index f2e94196d31f..07c5a8e52ca8 100644 > --- a/include/linux/iio/iio-opaque.h > +++ b/include/linux/iio/iio-opaque.h > @@ -11,6 +11,7 @@ > * @channel_attr_list: keep track of automatically created channel > * attributes > * @chan_attr_group: group for all attrs in base directory > + * @ioctl_handlers: ioctl handlers registered with the core handler > * @debugfs_dentry: device specific debugfs dentry > * @cached_reg_addr: cached register address for debugfs reads > * @read_buf: read buffer to be used for the initial reg read > @@ -22,6 +23,7 @@ struct iio_dev_opaque { > struct list_head buffer_list; > struct list_head channel_attr_list; > struct attribute_group chan_attr_group; > + struct list_head ioctl_handlers; > #if defined(CONFIG_DEBUG_FS) > struct dentry *debugfs_dentry; > unsigned cached_reg_addr;
