On Sun, Feb 24, 2013 at 12:03:00PM +0800, Zhang Yanfei wrote:
> This is just a tweak: using min_t/max_t to avoid `if (foo = bar)' thing.
- s/=/==/; s/[/]max_t//
But in any case the change is more than that.
I'd be happier with something like:
kexec: Use min_t to simplify logic
> Cc: "Eric W. Biederman" <ebiederm at xmission.com>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: Simon Horman <horms at verge.net.au>
> Signed-off-by: Zhang Yanfei <zhangyanfei at cn.fujitsu.com>
> ---
> kernel/kexec.c | 20 +++++---------------
> 1 files changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 2436ffc..065db87 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -822,13 +822,8 @@ static int kimage_load_normal_segment(struct kimage *image,
> /* Start with a clear page */
> clear_page(ptr);
> ptr += maddr & ~PAGE_MASK;
> - mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
> - if (mchunk > mbytes)
> - mchunk = mbytes;
> -
> - uchunk = mchunk;
> - if (uchunk > ubytes)
> - uchunk = ubytes;
> + mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK));
> + uchunk = min_t(size_t, ubytes, mchunk);
>
> result = copy_from_user(ptr, buf, uchunk);
> kunmap(page);
> @@ -874,13 +869,9 @@ static int kimage_load_crash_segment(struct kimage *image,
> }
> ptr = kmap(page);
> ptr += maddr & ~PAGE_MASK;
> - mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
> - if (mchunk > mbytes)
> - mchunk = mbytes;
> -
> - uchunk = mchunk;
> + mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK));
> + uchunk = min_t(size_t, ubytes, mchunk);
The line above means that uchunk can now never be greater than ubytes.
> if (uchunk > ubytes) {
So the following seems more appropriate to me:
if (mchunk > uchunk) {
> - uchunk = ubytes;
> /* Zero the trailing part of the page */
> memset(ptr + uchunk, 0, mchunk - uchunk);
> }
> @@ -1461,8 +1452,7 @@ void vmcoreinfo_append_str(const char *fmt, ...)
> r = vsnprintf(buf, sizeof(buf), fmt, args);
> va_end(args);
>
> - if (r + vmcoreinfo_size > vmcoreinfo_max_size)
> - r = vmcoreinfo_max_size - vmcoreinfo_size;
> + r = min_t(size_t, r, vmcoreinfo_max_size - vmcoreinfo_size);
>
> memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
>
> --
> 1.7.1
>
