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SubjectRe: [PATCH v9 08/20] gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL
On Tue, Sep 22, 2020 at 5:35 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for GPIO_V2_GET_LINEINFO_IOCTL and
> GPIO_V2_GET_LINEINFO_WATCH_IOCTL.
>
> The core of this change is the event kfifo switching to contain
> struct gpioline_info_changed_v2, instead of v1 as v2 is richer.
>
> The two uAPI versions are mostly independent - other than where they both
> provide line info changes via reads on the chip fd. As the info change
> structs differ between v1 and v2, the infowatch implementation tracks which
> version of the infowatch ioctl, either GPIO_GET_LINEINFO_WATCH_IOCTL or
> GPIO_V2_GET_LINEINFO_WATCH_IOCTL, initiates the initial watch and returns
> the corresponding info change struct to the read. The version supported
> on that fd locks to that version on the first watch request, so subsequent
> watches from that process must use the same uAPI version.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>
> Changes for v5:
> - as per cover letter
>
> Changes for v4:
> - replace strncpy with memcpy in gpio_v2_line_info_to_v1
>
> drivers/gpio/gpiolib-cdev.c | 197 +++++++++++++++++++++++++++++++-----
> 1 file changed, 169 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 7a3ed2617f74..d3857113f58c 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -181,7 +181,8 @@ static long linehandle_set_config(struct linehandle_state *lh,
> }
>
> blocking_notifier_call_chain(&desc->gdev->notifier,
> - GPIOLINE_CHANGED_CONFIG, desc);
> + GPIO_V2_LINE_CHANGED_CONFIG,
> + desc);
> }
> return 0;
> }
> @@ -353,7 +354,7 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
> }
>
> blocking_notifier_call_chain(&desc->gdev->notifier,
> - GPIOLINE_CHANGED_REQUESTED, desc);
> + GPIO_V2_LINE_CHANGED_REQUESTED, desc);
>
> dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
> offset);
> @@ -747,7 +748,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
> }
>
> blocking_notifier_call_chain(&desc->gdev->notifier,
> - GPIOLINE_CHANGED_REQUESTED, desc);
> + GPIO_V2_LINE_CHANGED_REQUESTED, desc);
>
> dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
> offset);
> @@ -1094,7 +1095,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
> goto out_free_le;
>
> blocking_notifier_call_chain(&desc->gdev->notifier,
> - GPIOLINE_CHANGED_REQUESTED, desc);
> + GPIO_V2_LINE_CHANGED_REQUESTED, desc);
>
> irq = gpiod_to_irq(desc);
> if (irq <= 0) {
> @@ -1161,17 +1162,59 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
> return ret;
> }
>
> +static void gpio_v2_line_info_to_v1(struct gpio_v2_line_info *info_v2,
> + struct gpioline_info *info_v1)
> +{
> + u64 flagsv2 = info_v2->flags;
> +
> + memcpy(info_v1->name, info_v2->name, sizeof(info_v1->name));

> + memcpy(info_v1->consumer, info_v2->consumer,
> + sizeof(info_v1->consumer));

One line?

> + info_v1->line_offset = info_v2->offset;
> + info_v1->flags = 0;
> +
> + if (flagsv2 & GPIO_V2_LINE_FLAG_USED)
> + info_v1->flags |= GPIOLINE_FLAG_KERNEL;
> +
> + if (flagsv2 & GPIO_V2_LINE_FLAG_OUTPUT)
> + info_v1->flags |= GPIOLINE_FLAG_IS_OUT;
> +
> + if (flagsv2 & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
> + info_v1->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
> +
> + if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_DRAIN)
> + info_v1->flags |= GPIOLINE_FLAG_OPEN_DRAIN;
> + if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_SOURCE)
> + info_v1->flags |= GPIOLINE_FLAG_OPEN_SOURCE;
> +
> + if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)
> + info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
> + if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN)
> + info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
> + if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_DISABLED)
> + info_v1->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
> +}
> +
> +static void gpio_v2_line_info_changed_to_v1(
> + struct gpio_v2_line_info_changed *lic_v2,
> + struct gpioline_info_changed *lic_v1)
> +{
> + gpio_v2_line_info_to_v1(&lic_v2->info, &lic_v1->info);
> + lic_v1->timestamp = lic_v2->timestamp_ns;
> + lic_v1->event_type = lic_v2->event_type;
> +}
> +
> #endif /* CONFIG_GPIO_CDEV_V1 */
>
> static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
> - struct gpioline_info *info)
> + struct gpio_v2_line_info *info)
> {
> struct gpio_chip *gc = desc->gdev->chip;
> bool ok_for_pinctrl;
> unsigned long flags;
>
> memset(info, 0, sizeof(*info));
> - info->line_offset = gpio_chip_hwgpio(desc);
> + info->offset = gpio_chip_hwgpio(desc);
>
> /*
> * This function takes a mutex so we must check this before taking
> @@ -1181,7 +1224,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
> * lock common to both frameworks?
> */
> ok_for_pinctrl =
> - pinctrl_gpio_can_use_line(gc->base + info->line_offset);
> + pinctrl_gpio_can_use_line(gc->base + info->offset);
>
> spin_lock_irqsave(&gpio_lock, flags);
>
> @@ -1202,23 +1245,27 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
> test_bit(FLAG_EXPORT, &desc->flags) ||
> test_bit(FLAG_SYSFS, &desc->flags) ||
> !ok_for_pinctrl)
> - info->flags |= GPIOLINE_FLAG_KERNEL;
> + info->flags |= GPIO_V2_LINE_FLAG_USED;
> +
> if (test_bit(FLAG_IS_OUT, &desc->flags))
> - info->flags |= GPIOLINE_FLAG_IS_OUT;
> + info->flags |= GPIO_V2_LINE_FLAG_OUTPUT;
> + else
> + info->flags |= GPIO_V2_LINE_FLAG_INPUT;
> +
> if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
> - info->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
> + info->flags |= GPIO_V2_LINE_FLAG_ACTIVE_LOW;
> +
> if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
> - info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
> - GPIOLINE_FLAG_IS_OUT);
> + info->flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
> if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
> - info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
> - GPIOLINE_FLAG_IS_OUT);
> + info->flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
> +
> if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
> - info->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
> + info->flags |= GPIO_V2_LINE_FLAG_BIAS_DISABLED;
> if (test_bit(FLAG_PULL_DOWN, &desc->flags))
> - info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
> + info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN;
> if (test_bit(FLAG_PULL_UP, &desc->flags))
> - info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
> + info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
>
> spin_unlock_irqrestore(&gpio_lock, flags);
> }
> @@ -1226,11 +1273,65 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
> struct gpio_chardev_data {
> struct gpio_device *gdev;
> wait_queue_head_t wait;
> - DECLARE_KFIFO(events, struct gpioline_info_changed, 32);
> + DECLARE_KFIFO(events, struct gpio_v2_line_info_changed, 32);
> struct notifier_block lineinfo_changed_nb;
> unsigned long *watched_lines;
> +#ifdef CONFIG_GPIO_CDEV_V1
> + atomic_t watch_abi_version;
> +#endif
> };
>
> +#ifdef CONFIG_GPIO_CDEV_V1
> +static int lineinfo_ensure_abi_version(struct gpio_chardev_data *cdata,
> + unsigned int version)
> +{

> + int abiv = atomic_read(&cdata->watch_abi_version);
> +
> + if (abiv == 0) {

> + atomic_cmpxchg(&cdata->watch_abi_version, 0, version);
> + abiv = atomic_read(&cdata->watch_abi_version);

atomic_cmpxchng() returns a value.
Also there are no barriers here...

> + }
> + if (abiv != version)
> + return -EPERM;

I'm not sure I understand why this is atomic.

Also this seems to be racy if cdata changed in background.

Shouldn't be rather

if (atomic_cmpxchg() == 0) {
if (atomic_read() != version)
return ...;
}

But here is still the question: why do you expect the version to be
changed on background? And what about barriers?

> + return 0;
> +}
> +#endif
> +
> +static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
> + bool watch)
> +{
> + struct gpio_desc *desc;
> + struct gpio_v2_line_info lineinfo;
> +
> + if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
> + return -EFAULT;
> +
> + if (memchr_inv(lineinfo.padding, 0, sizeof(lineinfo.padding)))
> + return -EINVAL;
> +
> + desc = gpiochip_get_desc(cdev->gdev->chip, lineinfo.offset);
> + if (IS_ERR(desc))
> + return PTR_ERR(desc);
> +
> + if (watch) {
> +#ifdef CONFIG_GPIO_CDEV_V1

> + if (lineinfo_ensure_abi_version(cdev, 2))
> + return -EPERM;

Can't you propagate error code from the function?

> +#endif
> + if (test_and_set_bit(lineinfo.offset, cdev->watched_lines))
> + return -EBUSY;
> + }
> + gpio_desc_to_lineinfo(desc, &lineinfo);
> +
> + if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
> + if (watch)
> + clear_bit(lineinfo.offset, cdev->watched_lines);
> + return -EFAULT;
> + }
> +
> + return 0;
> +}
> +
> /*
> * gpio_ioctl() - ioctl handler for the GPIO chardev
> */
> @@ -1240,7 +1341,6 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> struct gpio_device *gdev = cdev->gdev;
> struct gpio_chip *gc = gdev->chip;
> void __user *ip = (void __user *)arg;
> - struct gpio_desc *desc;
> __u32 offset;
>
> /* We fail any subsequent ioctl():s when the chip is gone */
> @@ -1263,7 +1363,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> return 0;
> #ifdef CONFIG_GPIO_CDEV_V1
> } else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
> + struct gpio_desc *desc;
> struct gpioline_info lineinfo;
> + struct gpio_v2_line_info lineinfo_v2;
>
> if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
> return -EFAULT;
> @@ -1273,7 +1375,8 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> if (IS_ERR(desc))
> return PTR_ERR(desc);
>
> - gpio_desc_to_lineinfo(desc, &lineinfo);
> + gpio_desc_to_lineinfo(desc, &lineinfo_v2);
> + gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
>
> if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
> return -EFAULT;
> @@ -1283,7 +1386,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> } else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
> return lineevent_create(gdev, ip);
> } else if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
> + struct gpio_desc *desc;
> struct gpioline_info lineinfo;
> + struct gpio_v2_line_info lineinfo_v2;
>
> if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
> return -EFAULT;
> @@ -1293,10 +1398,14 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> if (IS_ERR(desc))
> return PTR_ERR(desc);
>
> + if (lineinfo_ensure_abi_version(cdev, 1))
> + return -EPERM;
> +
> if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
> return -EBUSY;
>
> - gpio_desc_to_lineinfo(desc, &lineinfo);
> + gpio_desc_to_lineinfo(desc, &lineinfo_v2);
> + gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
>
> if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
> clear_bit(lineinfo.line_offset, cdev->watched_lines);
> @@ -1305,6 +1414,10 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>
> return 0;
> #endif /* CONFIG_GPIO_CDEV_V1 */
> + } else if (cmd == GPIO_V2_GET_LINEINFO_IOCTL ||
> + cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
> + return lineinfo_get(cdev, ip,
> + cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL);
> } else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
> return linereq_create(gdev, ip);
> } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
> @@ -1340,7 +1453,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
> unsigned long action, void *data)
> {
> struct gpio_chardev_data *cdev = to_gpio_chardev_data(nb);
> - struct gpioline_info_changed chg;
> + struct gpio_v2_line_info_changed chg;
> struct gpio_desc *desc = data;
> int ret;
>
> @@ -1349,7 +1462,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
>
> memset(&chg, 0, sizeof(chg));
> chg.event_type = action;
> - chg.timestamp = ktime_get_ns();
> + chg.timestamp_ns = ktime_get_ns();
> gpio_desc_to_lineinfo(desc, &chg.info);
>
> ret = kfifo_in_spinlocked(&cdev->events, &chg, 1, &cdev->wait.lock);
> @@ -1380,12 +1493,16 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
> size_t count, loff_t *off)
> {
> struct gpio_chardev_data *cdev = file->private_data;
> - struct gpioline_info_changed event;
> + struct gpio_v2_line_info_changed event;
> ssize_t bytes_read = 0;
> int ret;
> + size_t event_size;
>
> - if (count < sizeof(event))
> +#ifndef CONFIG_GPIO_CDEV_V1
> + event_size = sizeof(struct gpio_v2_line_info_changed);
> + if (count < event_size)
> return -EINVAL;
> +#endif
>
> do {
> spin_lock(&cdev->wait.lock);
> @@ -1407,7 +1524,17 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
> return ret;
> }
> }
> -
> +#ifdef CONFIG_GPIO_CDEV_V1
> + /* must be after kfifo check so watch_abi_version is set */
> + if (atomic_read(&cdev->watch_abi_version) == 2)
> + event_size = sizeof(struct gpio_v2_line_info_changed);
> + else
> + event_size = sizeof(struct gpioline_info_changed);
> + if (count < event_size) {
> + spin_unlock(&cdev->wait.lock);
> + return -EINVAL;
> + }
> +#endif
> ret = kfifo_out(&cdev->events, &event, 1);
> spin_unlock(&cdev->wait.lock);
> if (ret != 1) {
> @@ -1416,9 +1543,23 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
> /* We should never get here. See lineevent_read(). */
> }
>
> - if (copy_to_user(buf + bytes_read, &event, sizeof(event)))
> +#ifdef CONFIG_GPIO_CDEV_V1
> + if (event_size == sizeof(struct gpio_v2_line_info_changed)) {
> + if (copy_to_user(buf + bytes_read, &event, event_size))
> + return -EFAULT;
> + } else {
> + struct gpioline_info_changed event_v1;
> +
> + gpio_v2_line_info_changed_to_v1(&event, &event_v1);
> + if (copy_to_user(buf + bytes_read, &event_v1,
> + event_size))
> + return -EFAULT;
> + }
> +#else
> + if (copy_to_user(buf + bytes_read, &event, event_size))
> return -EFAULT;
> - bytes_read += sizeof(event);
> +#endif
> + bytes_read += event_size;
> } while (count >= bytes_read + sizeof(event));
>
> return bytes_read;
> --
> 2.28.0
>


--
With Best Regards,
Andy Shevchenko

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