[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>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/futex.h b/include/linux/futex.h
index 34c3a215f2cd..d097b5b72bc6 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -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);