Re: [PATCH, RFC, v2] shmat: introduce flag SHM_MAP_HINT

Andi Kleen
2008-10-07T08:20:30Z

On Tue, Oct 07, 2008 at 09:57:50AM +0300, Kirill A. Shutemov wrote:
> It allows interpret attach address as a hint, not as exact address.

Please expand the description a bit. Rationale. etc.

> @@ -55,6 +55,7 @@ struct shmid_ds {
> #define SHM_RND 020000 /* round attach address to SHMLBA boundary */
> #define SHM_REMAP 040000 /* take-over region on attach */
> #define SHM_EXEC 0100000 /* execution access */
> +#define SHM_MAP_HINT 0200000 /* interpret attach address as a hint */

search hint

> @@ -892,7 +892,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
> sfd->vm_ops = NULL;
>
> down_write(&current->mm->mmap_sem);
> - if (addr && !(shmflg & SHM_REMAP)) {
> + if (addr && !(shmflg & (SHM_REMAP|SHM_MAP_HINT))) {

I think you were right earlier that it can be just deleted, so why don't
you just do that?

-Andi

--
ak@linux.intel.com