Re: [Lcd4linux-devel] lcd4linux: Fatal bug in timer groups

[Marcus M. <cod...@gm...>]

Hello Michael, hello Mattia,


[Michael Reinelt]
> > What I currently do not understand: why would somebody do a
> > malloc(sizeof(int)) ??

[Mattia Jona-Lasinio]
> I totally agree :) and the answer is: I have no idea :)
> 
> The only reason I see is that when calling
> timer_add(timer_process_group, TimerGroups[group].interval, interval,
> 0) in timer_group.c, the time interval is passed as the argument of
> the callback function. But we can make the interval member in the
> TIMER_GROUP structure an int instead of int* and rewrite
> timer_add(timer_process_group, &TimerGroups[group].interval, interval,
> 0).

I haven't seen it on March 26, too. But now I think the int*/malloc
for the 'interval' element is very important:

The realloc in 'timer_add_group' could change the positions of all
already existing 'TimerGroups' (and their elements like 'interval')
AFTER the pointer to their 'interval' elements were given to the timers
via previous 'timer_add' calls. This will cause problems when
'timer_process' is called which will use the old addresses.

Ticket #281 (Segmentation fault) might be a result of that.

The int*/malloc-trick (or linked lists ;) ) avoid that problem.


Regards 

Marcus

-- 
NEU: FreePhone 3-fach-Flat mit kostenlosem Smartphone!                                  
Jetzt informieren: http://mobile.1und1.de/?ac=OM.PW.PW003K20328T7073a