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Commit 1b6ca2a6 authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
Browse files

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: default avatarAnton Blanchard <anton@samba.org>
Cc: <stable@kernel.org> # 3.0+
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 375f561a

arch/powerpc/kernel/sysfs.c

+8 −0
Original line number Original line Diff line number Diff line
@@ -194,6 +194,12 @@ static ssize_t show_dscr_default(struct device *dev, 
	return sprintf(buf, "%lx\n", dscr_default);

	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,

static ssize_t __used store_dscr_default(struct device *dev,

		struct device_attribute *attr, const char *buf,

		struct device_attribute *attr, const char *buf,

		size_t count)

		size_t count)
@@ -206,6 +212,8 @@ static ssize_t __used store_dscr_default(struct device *dev, 
		return -EINVAL;

		return -EINVAL;

	dscr_default = val;

	dscr_default = val;





	on_each_cpu(update_dscr, NULL, 1);



	return count;

	return count;

}

}