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| author | Anton Blanchard <anton@samba.org> | 2012-09-03 16:47:56 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-09-14 10:00:22 -0700 |
| commit | 652f43702b224351b790fd9182744d7946d4cdf6 (patch) | |
| tree | 417d56cf598b44311b7d4664e7348ae9285c3c37 | |
| parent | a9959bb7e1510edb3326beb354e59da0a6a0dab1 (diff) | |
| download | lwn-652f43702b224351b790fd9182744d7946d4cdf6.tar.gz lwn-652f43702b224351b790fd9182744d7946d4cdf6.zip | |
powerpc: Update DSCR on all CPUs when writing sysfs dscr_default
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>
| -rw-r--r-- | arch/powerpc/kernel/sysfs.c | 8 |
1 files changed, 8 insertions, 0 deletions
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; } |