lkml.org 
[lkml]   [2012]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[ 63/85] powerpc: Fix DSCR inheritance in copy_thread()
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Anton Blanchard <anton@samba.org>

commit 1021cb268b3025573c4811f1dee4a11260c4507b upstream.

If the default DSCR is non zero we set thread.dscr_inherit in
copy_thread() meaning the new thread and all its children will ignore
future updates to the default DSCR. This is not intended and is
a change in behaviour that a number of our users have hit.

We just need to inherit thread.dscr and thread.dscr_inherit from
the parent which ends up being much simpler.

This was found with the following test case:

http://ozlabs.org/~anton/junkcode/dscr_default_test.c

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/powerpc/kernel/process.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)

--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -799,16 +799,8 @@ int copy_thread(unsigned long clone_flag
#endif /* CONFIG_PPC_STD_MMU_64 */
#ifdef CONFIG_PPC64
if (cpu_has_feature(CPU_FTR_DSCR)) {
- if (current->thread.dscr_inherit) {
- p->thread.dscr_inherit = 1;
- p->thread.dscr = current->thread.dscr;
- } else if (0 != dscr_default) {
- p->thread.dscr_inherit = 1;
- p->thread.dscr = dscr_default;
- } else {
- p->thread.dscr_inherit = 0;
- p->thread.dscr = 0;
- }
+ p->thread.dscr_inherit = current->thread.dscr_inherit;
+ p->thread.dscr = current->thread.dscr;
}
#endif




\
 
 \ /
  Last update: 2012-09-13 03:41    [W:0.372 / U:6.664 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site