Messages in this thread | | | Date | Tue, 7 Oct 2008 09:57:03 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH, RFC] shmat: introduce flag SHM_MAP_HINT |
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On Mon, Oct 06, 2008 at 09:29:23PM +0200, Andi Kleen wrote: > On Mon, Oct 06, 2008 at 05:37:59PM +0300, Kirill A. Shutemov wrote: > > It allows interpret attach address as a hint, not as exact address. > > First you should also do a patch for the manpage and send to > the manpage maintainer.
I'll do it if the patch is ok.
> > #define SHM_LOCK 11 > > diff --git a/ipc/shm.c b/ipc/shm.c > > index e77ec69..19462bb 100644 > > --- a/ipc/shm.c > > +++ b/ipc/shm.c > > @@ -819,7 +819,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) > > if (shmid < 0) > > goto out; > > else if ((addr = (ulong)shmaddr)) { > > - if (addr & (SHMLBA-1)) { > > + if (!(shmflg & SHM_MAP_HINT) && (addr & (SHMLBA-1))) { > > if (shmflg & SHM_RND) > > addr &= ~(SHMLBA-1); /* round down */ > > else > > @@ -828,7 +828,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) > > #endif > > goto out; > > } > > - flags = MAP_SHARED | MAP_FIXED; > > + flags = (shmflg & SHM_MAP_HINT ? 0 : MAP_FIXED) | MAP_SHARED; > > > IMHO you need at least make the > > if (find_vma_intersection(current->mm, addr, addr + size)) > goto invalid; > > test above conditional too.
Since it's a hint, we shouldn't call find_vma_intersection() at all.
I'll send fixed patch soon.
-- Regards, Kirill A. Shutemov + Belarus, Minsk + ALT Linux Team, http://www.altlinux.com/ [unhandled content-type:application/pgp-signature] | |