Re: WARNING: fs/proc/generic.c:173 __xlate_proc_name

Re: WARNING: fs/proc/generic.c:173 __xlate_proc_name

[Stefan Wahren]

Hi,

[add lkml and linux-fsdevel]

Am 10.02.24 um 11:06 schrieb Stefan Wahren:
> Hi,
> we are using libgpiod-2.0.1 with Linux 6.1.49 on our Tarragon hardware
> platform. Recently we implemented an application which waits for GPIO
> interrupts and we were able to trigger a warning by naming the owner
> of the GPIO as "R1/S1":
>
> WARNING: CPU: 0 PID: 429 at fs/proc/generic.c:173
> __xlate_proc_name+0x78/0x98 name 'R1/S1'
> CPU: 0 PID: 429 Comm: cb_tarragon_dri Not tainted
> 6.1.49-00019-g9dbc76303a17 #147
> Hardware name: Freescale i.MX6 Ultralite (Device Tree)
> unwind_backtrace from show_stack+0x10/0x14
> show_stack from dump_stack_lvl+0x24/0x2c
> dump_stack_lvl from __warn+0x74/0xbc
> __warn from warn_slowpath_fmt+0xc8/0x120
> warn_slowpath_fmt from __xlate_proc_name+0x78/0x98
> __xlate_proc_name from __proc_create+0x3c/0x284
> __proc_create from _proc_mkdir+0x2c/0x70
> _proc_mkdir from proc_mkdir_data+0x10/0x18
> proc_mkdir_data from register_handler_proc+0xc8/0x118
> register_handler_proc from __setup_irq+0x554/0x664
> __setup_irq from request_threaded_irq+0xac/0x13c
> request_threaded_irq from edge_detector_setup+0xc0/0x1f8
> edge_detector_setup from linereq_create+0x30c/0x384
> linereq_create from vfs_ioctl+0x20/0x38
> vfs_ioctl from sys_ioctl+0xbc/0x8b0
> sys_ioctl from ret_fast_syscall+0x0/0x54
> Exception stack(0xe0b61fa8 to 0xe0b61ff0)
> 1fa0:                   01b019b8 01a9f428 0000000d c250b407 beeae888
> beeae880
> 1fc0: 01b019b8 01a9f428 01af7e40 00000036 beeaeb88 beeaeb80 beeaeb58
> beeaeb60
> 1fe0: 00000036 beeae868 b6a88569 b6a01ae6
> ---[ end trace 0000000000000000 ]---
>
> I'm not sure where this should be fixed.
>
since the discussion seems to stuck here [1], i reposted my original
mail to a wider audience.

Regards

[1] - https://lore.kernel.org/linux-gpio/20240213030409.GA35527@rigel/

Re: WARNING: fs/proc/generic.c:173 __xlate_proc_name

[Alexey Dobriyan]

> WARNING: CPU: 0 PID: 429 at fs/proc/generic.c:173
> __xlate_proc_name+0x78/0x98 name 'R1/S1'

proc_mkdir() didn't find 'R1' directory.

In other words, you can't have slashes in irq names.

Re: WARNING: fs/proc/generic.c:173 __xlate_proc_name

[Stefan Wahren]

Hi Alexey,

Am 25.02.24 um 11:37 schrieb Alexey Dobriyan:
>> WARNING: CPU: 0 PID: 429 at fs/proc/generic.c:173
>> __xlate_proc_name+0x78/0x98 name 'R1/S1'
> proc_mkdir() didn't find 'R1' directory.
>
> In other words, you can't have slashes in irq names.
we already came to the point in the discussion before (link in my last
mail). The problem is no libgpiod user (userspace) is aware of this. So
the next question is where it should be fixed?

Sorry, i took my original message because posting the last message to
linux-fsdevel without context would be pointless.

Regards

Re: WARNING: fs/proc/generic.c:173 __xlate_proc_name

[Alexey Dobriyan]

On Sun, Feb 25, 2024 at 11:47:30AM +0100, Stefan Wahren wrote:
> Hi Alexey,
> 
> Am 25.02.24 um 11:37 schrieb Alexey Dobriyan:
> > > WARNING: CPU: 0 PID: 429 at fs/proc/generic.c:173
> > > __xlate_proc_name+0x78/0x98 name 'R1/S1'
> > proc_mkdir() didn't find 'R1' directory.
> > 
> > In other words, you can't have slashes in irq names.
> we already came to the point in the discussion before (link in my last
> mail). The problem is no libgpiod user (userspace) is aware of this.

Changing '/' to '-' or '.' should be OK. Whatever you do, don't change
to '!' because it will make these paths annoying to use in bash.

> So the next question is where it should be fixed?

libgpiod silently weren't getting directory inside /proc/irq/${irq}
and nobody noticed until now.

I think returning error may be too harsh but replacing characters is not.

> Sorry, i took my original message because posting the last message to
> linux-fsdevel without context would be pointless.