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[ 61/85] powerpc: Update DSCR on all CPUs when writing sysfs dscr_default
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 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 <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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;
}




\
 
 \ /
  Last update: 2012-09-13 02:41    [W:0.376 / U:1.708 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site