Re: scsi: BUG in scsi_init_io

From: Dmitry Vyukov
Date: Tue Jan 31 2017 - 05:07:10 EST

On Tue, Jan 31, 2017 at 10:58 AM, Johannes Thumshirn <jthumshirn@xxxxxxx> wrote:
> [...]
>> Please-please-please, let's not use WARN for something that is not a
>> kernel bug and is user-triggerable. This makes it impossible to
>> automate kernel testing and requires hiring an army of people doing
>> mechanical job of sorting out WARNING reports into kernel-bugs and
>> non-kernel-bugs.
>> If the message is absolutely necessary (while kernel does not
>> generally explain every EINVAL on console), the following will do:
>> if (!blk_rq_nr_phys_segments(rq)) {
>> pr_err("you are doing something wrong\n");
>> return -EINVAL;
>> }
> Yes I understand that. OTOH having the WARN helps you finding the caller because
> of to the stack trace. But arguably that could be accomplished with function
> graph tracing as well. I'll re-send a v2 as a proper patch.

Thank you very much.
Stack trace can be done with dump_stack() if necessary, e.g.

pr_err("you are doing something wrong here:\n");