Re: USB: hub: Delete an error message for a failed memory allocation in usb_hub_clear_tt_buffer()

Geert Uytterhoeven
2017-12-07T07:40:10Z

Hi Alan,

On Wed, Dec 6, 2017 at 11:02 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Wed, 6 Dec 2017, SF Markus Elfring wrote:
>> >>> Does the existing memory allocation error message include the
>> >>> &udev->dev device name and driver name? If it doesn't, there will be
>> >>> no way for the user to tell that the error message is related to the
>> >>> device failure.
>> >>
>> >> No, but the effect is similar.
>> >>
>> >> OOM does a dump_stack() so this function's call tree is shown.
>> >
>> > A call stack doesn't tell you which device was being handled.
>>
>> Do you find a default Linux allocation failure report insufficient then?
>>
>> Would you like to to achieve that the requested information can be determined
>> from a backtrace?
>
> It is not practical to do this. The memory allocation routines do not
> for what purpose the memory is being allocated; hence when a failure
> occurs they cannot tell what device (or other part of the system) will
> be affected.

If even allocation of 24 bytes fails, lots of other devices and other parts of
the system will start failing really soon...

> That's why we have a secondary error message.

... and the secondary error message would still be useless.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds