On 26.10.2016 09:18, Cao jin wrote:
> Also refactor some code hunk for readability
>
> Signed-off-by: Cao jin <[email protected]>
> ---
> util/mmap-alloc.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
> index 5a85aa3..92c123a 100644
> --- a/util/mmap-alloc.c
> +++ b/util/mmap-alloc.c
> @@ -41,6 +41,11 @@ size_t qemu_fd_getpagesize(int fd)
>
> void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
> {
> + /* Make sure align is a power of 2 */
> + assert(!(align & (align - 1)));
> + /* Always align to host page size */
> + assert(align >= getpagesize());
Now you've moved code before the declaration of the local variables.
That's also some kind of ugly (and might not work with older versions of
C compilers?)...
> /*
> * Note: this always allocates at least one extra page of virtual address
> * space, even if size is already aligned.
> @@ -68,11 +73,6 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align,
> bool shared)
> return MAP_FAILED;
> }
>
> - /* Make sure align is a power of 2 */
> - assert(!(align & (align - 1)));
> - /* Always align to host page size */
> - assert(align >= getpagesize());
... so maybe simply move the setting of "offset" (which requires
"align") here right in front of the mmap() instead?
> ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
> MAP_FIXED |
> (fd == -1 ? MAP_ANONYMOUS : 0) |
> @@ -83,22 +83,20 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align,
> bool shared)
> return MAP_FAILED;
> }
>
> - ptr += offset;
> - total -= offset;
> -
> if (offset > 0) {
> - munmap(ptr - offset, offset);
> + munmap(ptr, offset);
> }
>
> /*
> * Leave a single PROT_NONE page allocated after the RAM block, to serve
> as
> * a guard page guarding against potential buffer overflows.
> */
> + total -= offset;
> if (total > size + getpagesize()) {
> - munmap(ptr + size + getpagesize(), total - size - getpagesize());
> + munmap(ptr1 + size + getpagesize(), total - size - getpagesize());
> }
>
> - return ptr;
> + return ptr1;
> }
Thomas
