lkml.org 
[lkml]   [2007]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Need lockdep help
Alan Stern wrote, On 12/04/2007 08:28 PM:

> On Tue, 4 Dec 2007, Jarek Poplawski wrote:

...

> But you have to consider hypothetical kernel bugs. That's exactly what
> lockdep is for -- to warn you about possible deadlocks that could be
> caused by bugs.
>
> As a simple example, if thread #1 does "lock(A); lock(B)" and thread
> #2 does "lock(B); lock(A)" then there's a possible bug. Lockdep should
> warn about you, and it does -- even if those two threads can never run
> at the same time.
>
> If lockdep warned about deadlocks only when they actually happened, it
> wouldn't be nearly so useful.


Sure! I probably missed your point... Lockdep always names reported locks,
so I meant 'hypothetical' only trying to explain lockdep with some other,
unknown or unnamed bugs.

So, depending on the code, above example with A & B could be a real bug
(even if very improbable but logically justified) or a false alarm (eg.
when we know both threads could never work at the same).

Jarek P.


\
 
 \ /
  Last update: 2007-12-04 21:15    [W:0.046 / U:0.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site