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SubjectRe: [PATCH] kernel: trace: blktrace: remove redundent memcpy() in compat_blk_trace_setup()
A quick review of this patch looks fine to me.

Although, using ARRAY_SIZE() for a character string seems to me a bit
over paranoid. But I'm fine with it, as it makes sure that the string
is an array and not a pointer.

Jens,

Can you give me an Acked-by?

-- Steve


On Sun, 03 Nov 2013 22:23:39 +0800
Chen Gang <gang.chen@asianux.com> wrote:

> do_blk_trace_setup() will fully initialize 'buts.name', so can remove
> the related memcpy(). And also use BLKTRACE_BDEV_SIZE and ARRAY_SIZE
> instead of hard code number '32'.
>
>
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
> include/linux/blktrace_api.h | 2 +-
> kernel/trace/blktrace.c | 3 +--
> 2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
> index a12f6ed..afc1343 100644
> --- a/include/linux/blktrace_api.h
> +++ b/include/linux/blktrace_api.h
> @@ -89,7 +89,7 @@ static inline int blk_trace_init_sysfs(struct device *dev)
> #ifdef CONFIG_COMPAT
>
> struct compat_blk_user_trace_setup {
> - char name[32];
> + char name[BLKTRACE_BDEV_SIZE];
> u16 act_mask;
> u32 buf_size;
> u32 buf_nr;
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 7f727b3..f785aef 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -579,13 +579,12 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
> .end_lba = cbuts.end_lba,
> .pid = cbuts.pid,
> };
> - memcpy(&buts.name, &cbuts.name, 32);
>
> ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
> if (ret)
> return ret;
>
> - if (copy_to_user(arg, &buts.name, 32)) {
> + if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
> blk_trace_remove(q);
> return -EFAULT;
> }



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