This is a note to let you know that I've just added the patch titled
powerpc: Update DSCR on all CPUs when writing sysfs dscr_default
to the 3.4-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-update-dscr-on-all-cpus-when-writing-sysfs-dscr_default.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 1b6ca2a6fe56e7697d57348646e07df08f43b1bb Mon Sep 17 00:00:00 2001
From: Anton Blanchard <[email protected]>
Date: Mon, 3 Sep 2012 16:47:56 +0000
Subject: powerpc: Update DSCR on all CPUs when writing sysfs dscr_default
From: Anton Blanchard <[email protected]>
commit 1b6ca2a6fe56e7697d57348646e07df08f43b1bb upstream.
Writing to dscr_default in sysfs doesn't actually change the DSCR -
we rely on a context switch on each CPU to do the work. There is no
guarantee we will get a context switch in a reasonable amount of time
so fire off an IPI to force an immediate change.
This issue was found with the following test case:
http://ozlabs.org/~anton/junkcode/dscr_explicit_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/sysfs.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -194,6 +194,12 @@ static ssize_t show_dscr_default(struct
return sprintf(buf, "%lx\n", dscr_default);
}
+static void update_dscr(void *dummy)
+{
+ if (!current->thread.dscr_inherit)
+ mtspr(SPRN_DSCR, dscr_default);
+}
+
static ssize_t __used store_dscr_default(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
@@ -206,6 +212,8 @@ static ssize_t __used store_dscr_default
return -EINVAL;
dscr_default = val;
+ on_each_cpu(update_dscr, NULL, 1);
+
return count;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/powerpc-update-dscr-on-all-cpus-when-writing-sysfs-dscr_default.patch
queue-3.4/powerpc-fix-dscr-inheritance-in-copy_thread.patch
queue-3.4/powerpc-restore-correct-dscr-in-context-switch.patch
queue-3.4/powerpc-keep-thread.dscr-and-thread.dscr_inherit-in-sync.patch
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