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Message-ID: <d2322db3-992a-f9c1-53c4-39efc9d957a4@kylinos.cn>
Date: Mon, 9 Aug 2021 12:21:47 +0800
From: Jackie Liu <liuyun01@...inos.cn>
To: Ian Pilcher <arequipeno@...il.com>, linux-block@...r.kernel.org,
linux-leds@...r.kernel.org
Cc: axboe@...nel.dk, pavel@....cz, linux-kernel@...r.kernel.org,
kernelnewbies@...nelnewbies.org
Subject: Re: [RFC PATCH v2 05/10] block: Add block device sysfs attribute to
set/clear/show LED
ÔÚ 2021/8/9 ÉÏÎç11:32, Ian Pilcher дµÀ:
> Add show & store functions in blk-ledtrig.c (attributes defined in genhd.c)
>
> Show function shows all available LEDs (LEDs associated with blkdev trigger);
> currently associated LED is shown in square brackets ([])
>
> Store function accepts either all whitespace or "none" to clear LED
>
> Signed-off-by: Ian Pilcher <arequipeno@...il.com>
> ---
> block/blk-ledtrig.c | 109 ++++++++++++++++++++++++++++++++++++++++++++
> block/blk-ledtrig.h | 8 ++++
> block/genhd.c | 8 ++++
> 3 files changed, 125 insertions(+)
>
> diff --git a/block/blk-ledtrig.c b/block/blk-ledtrig.c
> index 280fa9edc2dd..1af94dc7ea51 100644
> --- a/block/blk-ledtrig.c
> +++ b/block/blk-ledtrig.c
> @@ -6,6 +6,7 @@
> * Copyright 2021 Ian Pilcher <arequipeno@...il.com>
> */
>
> +#include <linux/ctype.h>
> #include <linux/genhd.h>
> #include <linux/leds.h>
> #include <linux/mutex.h>
> @@ -139,3 +140,111 @@ static int blk_ledtrig_dev_set(struct gendisk *const disk,
> led_set_exit_return:
> return ret;
> }
> +
> +
> +/*
> + *
> + * sysfs attribute store function to set or clear device LED
> + *
> + */
> +
> +// Returns a pointer to the first non-whitespace character in s (or a pointer
> +// to the terminating null).
> +static const char *blk_ledtrig_skip_whitespace(const char *s)
> +{
> + while (*s != 0 && isspace(*s))
> + ++s;
> +
> + return s;
> +}
> +
> +// Returns a pointer to the first whitespace character in s (or a pointer to
> +// the terminating null), which is effectively a pointer to the position *after*
> +// the last character in the non-whitespace token at the beginning of s. (s is
> +// expected to be the result of a previous call to blk_ledtrig_skip_whitespace.)
These are not linux kernel style comments.
> +static const char *blk_ledtrig_find_whitespace(const char *s)
> +{
> + while (*s != 0 && !isspace(*s))
> + ++s;
> +
> + return s;
> +}
> +
> +static bool blk_ledtrig_name_is_none(const char *const name, const size_t len)
> +{
> + static const char none[4] = "none"; // no terminating null
> +
> + return len == sizeof(none) && memcmp(name, none, sizeof(none)) == 0;
> +}
> +
> +ssize_t blk_ledtrig_dev_led_store(struct device *const dev,
> + struct device_attribute *const attr,
> + const char *const buf, const size_t count)
> +{
> + struct gendisk *const disk = dev_to_disk(dev);
> + const char *const led_name = blk_ledtrig_skip_whitespace(buf);
> + const char *const endp = blk_ledtrig_find_whitespace(led_name);
> + const ptrdiff_t name_len = endp - led_name; // always >= 0
> + int ret;
> +
> + if (name_len == 0 || blk_ledtrig_name_is_none(led_name, name_len)) {
> + blk_ledtrig_dev_clear(disk);
> + ret = 0;
> + } else {
> + ret = blk_ledtrig_dev_set(disk, led_name, name_len);
> + }
> +
> + if (ret < 0)
> + return ret;
> +
> + return count;
> +}
> +
> +
> +/*
> + *
> + * sysfs attribute show function for device LED
> + *
> + */
> +
> +ssize_t blk_ledtrig_dev_led_show(struct device *const dev,
> + struct device_attribute *const attr,
> + char *const buf)
> +{
> + struct gendisk *const disk = dev_to_disk(dev);
> + struct blk_ledtrig_led *bd_led, *disk_led;
> + int ret, c = 0;
> +
> + ret = mutex_lock_interruptible(&blk_ledtrig_mutex);
> + if (ret != 0)
> + goto led_show_exit_return;
> +
> + disk_led = rcu_dereference_protected(disk->led,
> + lockdep_is_held(&blk_ledtrig_mutex));
> +
> + if (disk_led == NULL)
> + c += sprintf(buf, "[none]");
> + else
> + c += sprintf(buf, "none");
> +
> + list_for_each_entry(bd_led, &blk_ledtrig_leds, leds_list_node) {
> +
> + ret = snprintf(buf + c, PAGE_SIZE - c - 1,
> + bd_led == disk_led ? " [%s]" : " %s",
> + bd_led->led->name);
> + if (ret >= PAGE_SIZE - c - 1) {
> + ret = -EOVERFLOW;
> + goto led_show_exit_unlock;
> + }
> +
> + c += ret;
> + }
> +
> + buf[c] = '\n';
> + ret = c + 1;
> +
> +led_show_exit_unlock:
> + mutex_unlock(&blk_ledtrig_mutex);
> +led_show_exit_return:
> + return ret;
> +}
> diff --git a/block/blk-ledtrig.h b/block/blk-ledtrig.h
> index 66a1302a4174..771000d43647 100644
> --- a/block/blk-ledtrig.h
> +++ b/block/blk-ledtrig.h
> @@ -18,6 +18,14 @@ static inline void blk_ledtrig_disk_init(struct gendisk *const disk)
>
> void blk_ledtrig_dev_clear(struct gendisk *const disk);
>
> +ssize_t blk_ledtrig_dev_led_store(struct device *const dev,
> + struct device_attribute *const attr,
> + const char *const buf, const size_t count);
> +
> +ssize_t blk_ledtrig_dev_led_show(struct device *const dev,
> + struct device_attribute *const attr,
> + char *const buf);
> +
> #else // CONFIG_BLK_LED_TRIGGERS
>
> static inline void blk_ledtrig_disk_init(const struct gendisk *disk) {}
> diff --git a/block/genhd.c b/block/genhd.c
> index 9fa734aeab0f..d5413a633410 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -1012,6 +1012,11 @@ static struct device_attribute dev_attr_fail_timeout =
> __ATTR(io-timeout-fail, 0644, part_timeout_show, part_timeout_store);
> #endif
>
> +#ifdef CONFIG_BLK_LED_TRIGGERS
> +static struct device_attribute dev_attr_led =
> + __ATTR(led, 0644, blk_ledtrig_dev_led_show, blk_ledtrig_dev_led_store);
> +#endif
> +
> static struct attribute *disk_attrs[] = {
> &dev_attr_range.attr,
> &dev_attr_ext_range.attr,
> @@ -1033,6 +1038,9 @@ static struct attribute *disk_attrs[] = {
> #endif
> #ifdef CONFIG_FAIL_IO_TIMEOUT
> &dev_attr_fail_timeout.attr,
> +#endif
> +#ifdef CONFIG_BLK_LED_TRIGGERS
> + &dev_attr_led.attr,
> #endif
> NULL
> };
>
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