Re: [PATCH 1/1] tty: vt: Remove redundant null check before kfree.

From: Sachin Kamat
Date: Wed Nov 21 2012 - 10:28:58 EST


On 21 November 2012 20:46, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Nov 21, 2012 at 08:21:40PM +0530, Sachin Kamat wrote:
>> On 21 November 2012 20:16, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>> > On Wed, Nov 21, 2012 at 10:49:07AM +0530, Sachin Kamat wrote:
>> >> kfree on a NULL pointer is a no-op.
>> >>
>> >> Signed-off-by: Sachin Kamat <sachin.kamat@xxxxxxxxxx>
>> >> ---
>> >> drivers/tty/vt/consolemap.c | 6 ++----
>> >> 1 files changed, 2 insertions(+), 4 deletions(-)
>> >>
>> >> diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
>> >> index 2aaa0c2..248381b 100644
>> >> --- a/drivers/tty/vt/consolemap.c
>> >> +++ b/drivers/tty/vt/consolemap.c
>> >> @@ -410,10 +410,8 @@ static void con_release_unimap(struct uni_pagedir *p)
>> >> kfree(p->inverse_translations[i]);
>> >> p->inverse_translations[i] = NULL;
>> >> }
>> >> - if (p->inverse_trans_unicode) {
>> >> - kfree(p->inverse_trans_unicode);
>> >> - p->inverse_trans_unicode = NULL;
>> >> - }
>> >> + kfree(p->inverse_trans_unicode);
>> >> + p->inverse_trans_unicode = NULL;
>> >
>> > kfree with NULL is a no-op, but the line after that just caused a kernel
>> > crash if it was NULL, so I can't accept this type of thing.
>> >
>> > Please be more careful.
>>
>> My mistake. Apologies for the same.
>>
>> Do we need to assign the pointer to NULL after freeing?
>
> It depends if it is checked later on, is it?

I will re-send this patch after deleting the assignment?

>
>> > What's with the patches@xxxxxxxxxx email address? What is that for?
>> That is a logging mechanism (done by patchwork) for all patches sent
>> by Linaro engineers.
>
> So you can track it internally? Why?

Yes. For tracking the status.
>
> greg k-h



--
With warm regards,
Sachin
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