[PATCH] pi-futex: robust-futex exit

Fix robust PI-futexes to be properly unlocked on unexpected exit.

For this to work the kernel has to know whether a futex is a PI or a
non-PI one, because the semantics are different.  Since the space in
relevant glibc data structures is extremely scarce, the best solution is
to encode the 'PI' information in bit 0 of the robust list pointer.
Existing (non-PI) glibc robust futexes have this bit always zero, so the
ABI is kept.  New glibc with PI-robust-futexes will set this bit.

Further fixes from Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2006-07-29 05:17:57 +02:00 committed by Linus Torvalds
parent 627371d73c
commit e3f2ddeac7
3 changed files with 89 additions and 39 deletions

View file

@ -96,7 +96,8 @@ struct robust_list_head {
long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout,
u32 __user *uaddr2, u32 val2, u32 val3);
extern int handle_futex_death(u32 __user *uaddr, struct task_struct *curr);
extern int
handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi);
#ifdef CONFIG_FUTEX
extern void exit_robust_list(struct task_struct *curr);