Re: BUG: sleeping function called from invalid context in submit_async_request

[Oliver Neukum <oneukum@suse.com>]

Hi,

On 26.06.26 23:26, sanan.hasanou@gmail.com wrote:

>   kzalloc_noprof include/linux/slab.h:1200 [inline]
>   submit_async_request+0xd2/0x9c0 drivers/usb/misc/uss720.c:137
>   set_1284_register drivers/usb/misc/uss720.c:237 [inline]
>   parport_uss720_write_data+0x70/0x130 drivers/usb/misc/uss720.c:337
>   lcd_write_cmd_p8+0x94/0x7f0 drivers/auxdisplay/panel.c:752
>   hd44780_common_init_display+0x188/0x4f0 drivers/auxdisplay/hd44780_common.c:124
>   charlcd_init drivers/auxdisplay/charlcd.c:585 [inline]
>   charlcd_register+0x1e6/0x320 drivers/auxdisplay/charlcd.c:652
>   panel_attach+0x19f9/0x1f20 drivers/auxdisplay/panel.c:1644
>   driver_check+0x51/0x60 drivers/parport/share.c:158

Are you connecting an auxdisplay to a USB parport?
It seems the issue is that

static void lcd_write_cmd_p8(struct hd44780_common *hdc, int cmd)
{
         spin_lock_irq(&pprt_lock);
         /* present the data to the data port */
         w_dtr(pprt, cmd);

assumes that you can write to a parport with a spinlock held.
uss720 assumes that the method implementing that can use GFP_KERNEL.

I am not sure whether this was even ever defined.
Adding relevant people.

	Regards
		Oliver