svn commit: r326314 - in head/sys: ddb kern sys

[Edward Napierala]

2017-11-28 17:04 GMT+00:00 Bruce Evans <brde at optusnet.com.au>:

> On Tue, 28 Nov 2017, Edward Tomasz Napierala wrote:
>
> Log:
>>  Make kdb_reenter() silent when explicitly called from db_error().
>>  This removes the useless backtrace on various ddb(4) user errors.
>>
>>  Reviewed by:   jhb@
>>  Obtained from: CheriBSD
>>  MFC after:     2 weeks
>>  Sponsored by:  DARPA, AFRL
>>  Differential Revision: https://reviews.freebsd.org/D13212
>>
>
> This doesn't fix the spam for user errors that cause a trap, which are
> very common (for mistyping memory addresses).  ddb sets up trap handlers
> using setjmp, and actually does this correctly in many cases, but when
> a trap occurs the error handling is:
>
> trap -> kdb_reenter (print spam here) -> ddb (print error message here)
>

Indeed.  But, as you said later in that email, some of those messages
actually are (or might be) useful.  The intent of that change was only to
silence down those that certainly are not.  Also, differently from silencing
them down with a sysctl, this change makes them silent out of the box.

Agreed about the style problems; I might (can't promise, though) fix that
later.