This is a note to let you know that I've just added the patch titled
powerpc: Fix DSCR inheritance in copy_thread()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-fix-dscr-inheritance-in-copy_thread.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 1021cb268b3025573c4811f1dee4a11260c4507b Mon Sep 17 00:00:00 2001
From: Anton Blanchard <[email protected]>
Date: Mon, 3 Sep 2012 16:49:47 +0000
Subject: powerpc: Fix DSCR inheritance in copy_thread()
From: Anton Blanchard <[email protected]>
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 <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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
@@ -794,16 +794,8 @@ 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
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/powerpc-fix-dscr-inheritance-in-copy_thread.patch
queue-3.0/powerpc-restore-correct-dscr-in-context-switch.patch
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