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auxdisplay: linedisp: Use unique number for id

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The absence of decrementation of linedisp_id is incorrect in two ways,
i.e. it may cause:
- an ID exhaustion
- (and if the above is addressed) a duplicate id number may be allocated
  next time a device is added

Replace above mentioned approach by using IDA framework.

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Andy Shevchenko 2024-02-12 19:01:36 +02:00
parent 2327960f0c
commit 50d6b9d56e
2 changed files with 12 additions and 3 deletions
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13
drivers/auxdisplay/line-display.c
View File

@ -11,6 +11,7 @@
#include <generated/utsrelease.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
@ -188,11 +189,14 @@ static struct attribute *linedisp_attrs[] = {
};
ATTRIBUTE_GROUPS(linedisp);
static DEFINE_IDA(linedisp_id);
static void linedisp_release(struct device *dev)
{
struct linedisp *linedisp = container_of(dev, struct linedisp, dev);
kfree(linedisp->message);
ida_free(&linedisp_id, linedisp->id);
}
static const struct device_type linedisp_type = {
@ -214,7 +218,6 @@ int linedisp_register(struct linedisp *linedisp, struct device *parent,
unsigned int num_chars, char *buf,
void (*update)(struct linedisp *linedisp))
{
static atomic_t linedisp_id = ATOMIC_INIT(-1);
int err;
memset(linedisp, 0, sizeof(*linedisp));
@ -225,9 +228,13 @@ int linedisp_register(struct linedisp *linedisp, struct device *parent,
linedisp->num_chars = num_chars;
linedisp->scroll_rate = DEFAULT_SCROLL_RATE;
err = ida_alloc(&linedisp_id, GFP_KERNEL);
if (err < 0)
return err;
linedisp->id = err;
device_initialize(&linedisp->dev);
dev_set_name(&linedisp->dev, "linedisp.%lu",
(unsigned long)atomic_inc_return(&linedisp_id));
dev_set_name(&linedisp->dev, "linedisp.%u", linedisp->id);
/* initialise a timer for scrolling the message */
timer_setup(&linedisp->timer, linedisp_scroll, 0);

2
drivers/auxdisplay/line-display.h
View File

@ -22,6 +22,7 @@
* @message_len: the length of the @message string
* @scroll_pos: index of the first character of @message currently displayed
* @scroll_rate: scroll interval in jiffies
* @id: instance id of this display
*/
struct linedisp {
struct device dev;
@ -33,6 +34,7 @@ struct linedisp {
unsigned int message_len;
unsigned int scroll_pos;
unsigned int scroll_rate;
unsigned int id;
};
int linedisp_register(struct linedisp *linedisp, struct device *parent,