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. Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> --- drivers/auxdisplay/line-display.c | 13 ++++++++++--- drivers/auxdisplay/line-display.h | 2 ++ 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c index 310e9bfb41ae..c4dbb13293d1 100644 --- a/drivers/auxdisplay/line-display.c +++ b/drivers/auxdisplay/line-display.c @@ -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); diff --git a/drivers/auxdisplay/line-display.h b/drivers/auxdisplay/line-display.h index 0f5891d34c48..1fbe57fdc4cb 100644 --- a/drivers/auxdisplay/line-display.h +++ b/drivers/auxdisplay/line-display.h @@ -14,6 +14,7 @@ /** * struct linedisp - character line display private data structure * @dev: the line display device + * @id: instance id of this display * @timer: timer used to implement scrolling * @update: function called to update the display * @buf: pointer to the buffer for the string currently displayed @@ -25,6 +26,7 @@ */ struct linedisp { struct device dev; + unsigned int id; struct timer_list timer; void (*update)(struct linedisp *linedisp); char *buf; -- 2.43.0.rc1.1.gbec44491f096