From: Anton Blanchard Date: Mon, 3 Sep 2012 16:47:56 +0000 (+0000) Subject: powerpc: Update DSCR on all CPUs when writing sysfs dscr_default X-Git-Tag: v3.6-rc5~13^2~5 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=1b6ca2a6fe56e7697d57348646e07df08f43b1bb powerpc: Update DSCR on all CPUs when writing sysfs dscr_default 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 Cc: # 3.0+ Signed-off-by: Benjamin Herrenschmidt --- diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index 3529446c2abd..d4cbbd1fa75f 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -194,6 +194,12 @@ static ssize_t show_dscr_default(struct device *dev, 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(struct device *dev, return -EINVAL; dscr_default = val; + on_each_cpu(update_dscr, NULL, 1); + return count; }