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SubjectRe: [PATCH 1/3] uml: drivers/net_user.c memory leak fix
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Am Freitag 08 Juli 2011, 15:00:44 schrieb Vitaliy Ivanov:
> > > > This control logic is a bit strange.
> > > > When change_tramp() fails we should not printk() the output variable.
> > > >
> > > > if (pid < 0){
> > > >
> > > > free(output);
> > > > return;
> > > >
> > > > }
> > > >
> > > > Would be much cleaner.
> > >
> > > I just didn't want to clone this free-return stuff. So, what you
> > > proposing is like this:
> > > ------------
> > > ...
> > >
> > > output = uml_kmalloc(output_len, UM_GFP_KERNEL);
> > > if (output == NULL)
> > >
> > > printk(UM_KERN_ERR "change : failed to allocate output
> > > "
> > >
> > > "buffer\n");
> > >
> > > pid = change_tramp(argv, output, output_len);
> > > if (pid < 0) {
> > >
> > > free(output); <---------- I'm not sure
> > > but 'output' can be NULL here. return;
> > >
> > > }
> > >
> > > if (output != NULL) {
> > >
> > > printk("%s", output);
> > > kfree(output);
> > >
> > > }
> > >
> > > }
> > > ------------
> > >
> > > I was trying to print 'output' only in case change_tramp is
> > > successful. That's the old logic. And at the same time perform free
> > > only in case output is not NULL.
> >
> > Why?
> > Freeing a NULL pointer is perfectly fine.
>
> I should agree that something that you propose has better readability.
>
> So, here is updated patch.
>
> Thanks
> ---
>
> >From b0c5ca0336cc94b2fda251e0da7918394e59c5cd Mon Sep 17 00:00:00 2001
>
> From: Vitaliy Ivanov <vitalivanov@gmail.com>
> Date: Fri, 8 Jul 2011 14:54:29 +0300
> Subject: [PATCH] uml: drivers/net_user.c memory leak fix
>
> Perform memory cleanup on exit.
> On receiving invalid 'pid' we still should clean 'output' variable.
>
> Signed-off-by: Vitaliy Ivanov <vitalivanov@gmail.com>
> Signed-off-by: Richard Weinberger <richard@nod.at>

Why are you adding my Signed-off-by?!
That's my job...

> ---
> arch/um/drivers/net_user.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c
> index 9415dd9..5201188 100644
> --- a/arch/um/drivers/net_user.c
> +++ b/arch/um/drivers/net_user.c
> @@ -228,7 +228,10 @@ static void change(char *dev, char *what, unsigned
> char *addr, "buffer\n");
>
> pid = change_tramp(argv, output, output_len);
> - if (pid < 0) return;
> + if (pid < 0) {
> + kfree(output);
> + return;
> + }
>
> if (output != NULL) {
> printk("%s", output);

Anyway, Applied!

Thanks,
//richard


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