lkml.org 
[lkml]   [2008]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] led: simplify led_trigger_register_simple
From
Date
On Thu, 2008-11-20 at 16:14 +0200, Felipe Balbi wrote:
> > In answer to your question about kfree, I agree it needs to be called
> > upon error. The callers should just be calling
> > led_trigger_unregister_simple() in their failure paths though which
> > should take care of all problems? I know we used to register the simple
> > triggers late in paths so no error handling was needed to keep the code
> > simple and minimise the LED triggers impact on those systems.
>
> Well, led_trigger_register_simple() doesn't return anything. Imagine
> led_trigger_register_simple() fails, but the driver author decides
> it's not a failure if, let's say, a led doesn't turn on when we insert
> a mmc card to the slot since it doesn't change functionality.
>
> Now, imagine the user notes the led is not turning on and decides to
> unload and reload the module to try again. Once again the led doesn't go
> on. If the user keeps trying, it's quite a dangerous memory leak, right
> ?

So we have the module loading and one of two things happens:

led_trigger_register_simple() succeeds
led_trigger_register_simple() fails (probably from kmalloc failure)

The module doesn't know or care which happened. When the module unloads
it calls led_trigger_unregister_simple() which will free the memory in
the success case and do nothing in the case where it had failed.

So there is no memory leak?

Cheers,

Richard



\
 
 \ /
  Last update: 2008-11-20 16:03    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site