Messages in this thread | | | Subject | Re: [GIT pull] futex fixes for 2.6.31 | From | "Zhang, Yanmin" <> | Date | Thu, 25 Jun 2009 10:43:46 +0800 |
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On Wed, 2009-06-24 at 21:48 +0200, Thomas Gleixner wrote: > Linus, > > Please pull the latest futexes-for-linus git tree from: > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git futexes-for-linus > > Thanks, > > tglx > > ------------------> > Thomas Gleixner (1): > futex: Fix the write access fault problem for real > > > kernel/futex.c | 45 ++++++++++++++++++++++++--------------------- > 1 files changed, 24 insertions(+), 21 deletions(-) > > diff --git a/kernel/futex.c b/kernel/futex.c > index 80b5ce7..1c33711 100644 > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -284,6 +284,25 @@ void put_futex_key(int fshared, union futex_key *key) > drop_futex_key_refs(key); > } > > +/* > + * fault_in_user_writeable - fault in user address and verify RW access > + * @uaddr: pointer to faulting user space address > + * > + * Slow path to fixup the fault we just took in the atomic write > + * access to @uaddr. > + * > + * We have no generic implementation of a non destructive write to the > + * user address. We know that we faulted in the atomic pagefault > + * disabled section so we can as well avoid the #PF overhead by > + * calling get_user_pages() right away. > + */ > +static int fault_in_user_writeable(u32 __user *uaddr) > +{ > + int ret = get_user_pages(current, current->mm, (unsigned long)uaddr, > + sizeof(*uaddr), 1, 0, NULL, NULL); The 4th parameter of get_user_pages means page number. sizeof(*uaddr) is equal to 4, so you want 4 pages?
Yanmin
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