On Mon, 25 Feb 2013 09:36:51 +0900
Simon Horman <horms at verge.net.au> wrote:
> On Sun, Feb 24, 2013 at 10:37:21PM +0800, Zhang Yanfei wrote:
> > From: Zhang Yanfei <zhangyanfei at cn.fujitsu.com>
> >
> > This is just a tweak: using min_t to simplify logic of variable
> > assignments.
> >
> > v2:
> > - Rewrite patch description as Simon suggested.
> > - Fix an inappropriate if test introduced by v1. Thanks Simon.
>
> Hi Zhang,
>
> thanks for the update.
>
> Signed-off-by: Simon Horman <horms at verge.net.au>
Signed-off-by: implies that you were involved in the development or
patch delivery. Were you? If not, an Acked-by or Reviewed-by is more
appropriate.
Also, the need to use min_t rather than min is a sign that the types
are screwed up. Let's take a look.
> >
> > diff --git a/kernel/kexec.c b/kernel/kexec.c
> > index 2436ffc..effd655 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);
The types of ubytes and mbytes are clearly wrong. They are initialised
from a size_t and they are manipulated alongside size_t's.
The types of PAGE_SIZE and PAGE_MASK are vague - iirc they once had
different types on different architectures, so some form of casting is
unavoidable here.
> > 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;
> > - if (uchunk > ubytes) {
> > - uchunk = ubytes;
> > + mchunk = min_t(size_t, mbytes, PAGE_SIZE - (maddr & ~PAGE_MASK));
> > + uchunk = min_t(size_t, ubytes, mchunk);
> > + if (mchunk > uchunk) {
> > /* Zero the trailing part of the page */
> > memset(ptr + uchunk, 0, mchunk - uchunk);
> > }
Again, mybtes and ubytes have the wrong type.
> > @@ -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);
vmcoreinfo_max_size is a size_t and vmcoreinfo_size is a size_t and
memcpy's `size' argument is a size_t. Therefore the type of `r' should
be... what? int! bzzzzt.
