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Message-Id: <20210729015344.3366750-5-arequipeno@gmail.com>
Date: Wed, 28 Jul 2021 20:53:40 -0500
From: Ian Pilcher <arequipeno@...il.com>
To: linux-block@...r.kernel.org, linux-leds@...r.kernel.org
Cc: axboe@...nel.dk, pavel@....cz, linux-kernel@...r.kernel.org,
kernelnewbies@...nelnewbies.org, Ian Pilcher <arequipeno@...il.com>
Subject: [RFC PATCH 4/8] block: Add block class attributes to manage LED trigger list
* New class attributes - /sys/class/block/led_trigger_{new,list,del}
* Add init function - blk_ledtrig_init() - to create the attributes
in sysfs. Call blk_ledtrig_init() from genhd_device_init() (in
block/genhd.c).
* New file - block/blk-ledtrig.h
Signed-off-by: Ian Pilcher <arequipeno@...il.com>
---
block/blk-ledtrig.c | 147 ++++++++++++++++++++++++++++++++++++++++++++
block/blk-ledtrig.h | 22 +++++++
block/genhd.c | 2 +
3 files changed, 171 insertions(+)
create mode 100644 block/blk-ledtrig.h
diff --git a/block/blk-ledtrig.c b/block/blk-ledtrig.c
index c69ea1539336..6392ab4169f9 100644
--- a/block/blk-ledtrig.c
+++ b/block/blk-ledtrig.c
@@ -7,11 +7,15 @@
*/
#include <linux/blk-ledtrig.h>
+#include <linux/ctype.h>
+#include <linux/genhd.h>
#include <linux/leds.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include "blk-ledtrig.h"
+
/*
*
@@ -201,3 +205,146 @@ int blk_ledtrig_delete(const char *const name)
return __blk_ledtrig_delete(name, strlen(name));
}
EXPORT_SYMBOL_GPL(blk_ledtrig_delete);
+
+
+/*
+ *
+ * Class attributes to manage the trigger list
+ *
+ */
+
+static ssize_t blk_ledtrig_attr_store(struct class *, struct class_attribute *,
+ const char *, const size_t);
+static ssize_t blk_ledtrig_list_show(struct class *, struct class_attribute *,
+ char *);
+
+static struct class_attribute blk_ledtrig_attr_new =
+ __ATTR(led_trigger_new, 0200, 0, blk_ledtrig_attr_store);
+
+static struct class_attribute blk_ledtrig_attr_del =
+ __ATTR(led_trigger_del, 0200, 0, blk_ledtrig_attr_store);
+
+static struct class_attribute blk_ledtrig_attr_list =
+ __ATTR(led_trigger_list, 0444, blk_ledtrig_list_show, 0);
+
+// Returns a pointer to the first non-whitespace character in s (or a pointer
+// to the terminating nul).
+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 nul), 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.)
+static const char *blk_ledtrig_find_whitespace(const char *s)
+{
+ while (*s != 0 && !isspace(*s))
+ ++s;
+
+ return s;
+}
+
+static ssize_t blk_ledtrig_attr_store(struct class *const class,
+ struct class_attribute *const attr,
+ const char *const buf,
+ const size_t count)
+{
+ const char *const name = blk_ledtrig_skip_whitespace(buf);
+ const char *const endp = blk_ledtrig_find_whitespace(name);
+ const ptrdiff_t name_len = endp - name; // always >= 0
+ int ret;
+
+ if (attr == &blk_ledtrig_attr_new)
+ ret = __blk_ledtrig_create(name, name_len);
+ else // attr == &blk_ledtrig_attr_del
+ ret = __blk_ledtrig_delete(name, name_len);
+
+ if (ret < 0)
+ return ret;
+
+ // Avoid potential "empty name" error by skipping whitespace
+ // to next token or terminating nul
+ return blk_ledtrig_skip_whitespace(endp) - buf;
+}
+
+static ssize_t blk_ledtrig_list_show(struct class *const class,
+ struct class_attribute *const attr,
+ char *const buf)
+{
+ struct list_head *n;
+ int ret, c = 0;
+
+ ret = mutex_lock_interruptible(&blk_ledtrig_list_mutex);
+ if (unlikely(ret != 0))
+ goto list_exit_return;
+
+ list_for_each(n, &blk_ledtrig_list) {
+
+ struct blk_ledtrig *const t = blk_ledtrig_from_node(n);
+ int refcount;
+
+ ret = mutex_lock_interruptible(&t->refcount_mutex);
+ if (unlikely(ret != 0))
+ goto list_exit_unlock_list;
+
+ refcount = t->refcount;
+
+ mutex_unlock(&t->refcount_mutex);
+
+ ret = snprintf(buf + c, PAGE_SIZE - c, "%s: %d\n",
+ t->name, refcount);
+ if (unlikely(ret < 0))
+ goto list_exit_unlock_list;
+
+ c += ret;
+ if (unlikely(c >= PAGE_SIZE)) {
+ ret = -EOVERFLOW;
+ goto list_exit_unlock_list;
+ }
+ }
+
+ ret = c;
+
+list_exit_unlock_list:
+ mutex_unlock(&blk_ledtrig_list_mutex);
+list_exit_return:
+ return ret;
+}
+
+
+/*
+ *
+ * Initialization - create the class attributes
+ *
+ */
+
+void __init blk_ledtrig_init(void)
+{
+ int ret;
+
+ ret = class_create_file(&block_class, &blk_ledtrig_attr_new);
+ if (unlikely(ret != 0))
+ goto init_error_new;
+
+ ret = class_create_file(&block_class, &blk_ledtrig_attr_del);
+ if (unlikely(ret != 0))
+ goto init_error_del;
+
+ ret = class_create_file(&block_class, &blk_ledtrig_attr_list);
+ if (unlikely(ret != 0))
+ goto init_error_list;
+
+ return;
+
+init_error_list:
+ class_remove_file(&block_class, &blk_ledtrig_attr_del);
+init_error_del:
+ class_remove_file(&block_class, &blk_ledtrig_attr_new);
+init_error_new:
+ pr_err("failed to initialize blkdev LED triggers (%d)\n", ret);
+}
diff --git a/block/blk-ledtrig.h b/block/blk-ledtrig.h
new file mode 100644
index 000000000000..894843249deb
--- /dev/null
+++ b/block/blk-ledtrig.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * Block device LED triggers
+ *
+ * Copyright 2021 Ian Pilcher <arequipeno@...il.com>
+ */
+
+#ifndef _BLOCK_BLK_LEDTRIG_H
+#define _BLOCK_BLK_LEDTRIG_H
+
+#ifdef CONFIG_BLK_LED_TRIGGERS
+
+void blk_ledtrig_init(void);
+
+#else // CONFIG_BLK_LED_TRIGGERS
+
+static inline void blk_ledtrig_init(void) {}
+
+#endif // CONFIG_BLK_LED_TRIGGERS
+
+#endif // _BLOCK_BLK_LEDTRIG_H
diff --git a/block/genhd.c b/block/genhd.c
index af4d2ab4a633..d0b1d8f743ae 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -26,6 +26,7 @@
#include <linux/badblocks.h>
#include "blk.h"
+#include "blk-ledtrig.h"
static struct kobject *block_depr;
@@ -824,6 +825,7 @@ static int __init genhd_device_init(void)
if (unlikely(error))
return error;
blk_dev_init();
+ blk_ledtrig_init();
register_blkdev(BLOCK_EXT_MAJOR, "blkext");
--
2.31.1
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