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SubjectRe: [PATCH] remove redundant NULL checks before kfree() in drivers/video/
Date
On Sunday 20 March 2005 06:59, Jesper Juhl wrote:
> Checking a pointer for NULL before calling kfree() on it is redundant,
> kfree() deals with NULL pointers just fine.
> This patch removes such checks from files in drivers/video/
>
> Since this is a fairly trivial change (and the same change made
> everywhere) I've just made a single patch for all the files and CC all
> authors/maintainers of those files I could find for comments. If spliting
> this into one patch pr file is prefered, then I can easily do that as
> well.
>

[snip]

> --- linux-2.6.11-mm4-orig/drivers/video/console/bitblit.c 2005-03-16
> 15:45:26.000000000 +0100 +++
> linux-2.6.11-mm4/drivers/video/console/bitblit.c 2005-03-19
> 22:27:39.000000000 +0100 @@ -199,8 +199,7 @@ static void bit_putcs(struct
> vc_data *vc
> count -= cnt;
> }
>
> - if (buf)
> - kfree(buf);
> + kfree(buf);
> }
>

This is performance critical, so I would like the check to remain. A comment
may be added in this section.

> static void bit_clear_margins(struct vc_data *vc, struct fb_info *info,
> @@ -273,8 +272,7 @@ static void bit_cursor(struct vc_data *v
> dst = kmalloc(w * vc->vc_font.height, GFP_ATOMIC);
> if (!dst)
> return;
> - if (ops->cursor_data)
> - kfree(ops->cursor_data);
> + kfree(ops->cursor_data);
> ops->cursor_data = dst;
> update_attr(dst, src, attribute, vc);
> src = dst;
> @@ -321,8 +319,7 @@ static void bit_cursor(struct vc_data *v
> if (!mask)
> return;
>
> - if (ops->cursor_state.mask)
> - kfree(ops->cursor_state.mask);
> + kfree(ops->cursor_state.mask);
> ops->cursor_state.mask = mask;

Although these are also performance critical, I will agree that the checks
can go. Very rarely will ops->cursor_state.mask and ops->cursor_data be
NULL.

As for the rest, they are acceptable, as long as the maintainers agree.

Tony


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