From e3e3bf40916c1e810df03958cfa7ba6883cdce79 Mon Sep 17 00:00:00 2001 From: Hongyan Xu Date: Sat, 15 Aug 2026 18:59:50 +0800 Subject: [PATCH] auxdisplay: charlcd: cancel backlight work on registration failure With CONFIG_CHARLCD_BL_FLASH, charlcd_init() schedules bl_work before charlcd_register() calls misc_register(). If registration fails, the caller frees the charlcd object while delayed work still contains its address. Add charlcd_deinit() to cancel the delayed work and turn the backlight off. Use it for both registration rollback and normal unregistration. Fixes: 39f8ea46724e ("auxdisplay: charlcd: Extract character LCD core from misc/panel") Cc: stable@vger.kernel.org Reviewed-by: Geert Uytterhoeven Signed-off-by: Hongyan Xu Signed-off-by: Andy Shevchenko --- drivers/auxdisplay/charlcd.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c index 09020bb8ad15..ae2692ec3963 100644 --- a/drivers/auxdisplay/charlcd.c +++ b/drivers/auxdisplay/charlcd.c @@ -595,6 +595,16 @@ static int charlcd_init(struct charlcd *lcd) return 0; } +static void charlcd_deinit(struct charlcd *lcd) +{ + struct charlcd_priv *priv = charlcd_to_priv(lcd); + + if (lcd->ops->backlight) { + cancel_delayed_work_sync(&priv->bl_work); + lcd->ops->backlight(lcd, CHARLCD_OFF); + } +} + struct charlcd *charlcd_alloc(unsigned int drvdata_size) { struct charlcd_priv *priv; @@ -654,8 +664,10 @@ int charlcd_register(struct charlcd *lcd) return ret; ret = misc_register(&charlcd_dev); - if (ret) + if (ret) { + charlcd_deinit(lcd); return ret; + } the_charlcd = lcd; register_reboot_notifier(&panel_notifier); @@ -665,16 +677,11 @@ EXPORT_SYMBOL_GPL(charlcd_register); int charlcd_unregister(struct charlcd *lcd) { - struct charlcd_priv *priv = charlcd_to_priv(lcd); - unregister_reboot_notifier(&panel_notifier); charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-"); misc_deregister(&charlcd_dev); the_charlcd = NULL; - if (lcd->ops->backlight) { - cancel_delayed_work_sync(&priv->bl_work); - priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF); - } + charlcd_deinit(lcd); return 0; }