On Wed, Feb 22, 2012 at 07:43:17PM +0530, Rabin Vincent wrote:

On Mon, Feb 20, 2012 at 04:16:01PM +0000, Russell King - ARM Linux wrote:

quoted

On Sat, Jan 28, 2012 at 07:05:20PM +0530, Rabin Vincent wrote:

quoted

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index c0062ad..e9488ad 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c

@@ -125,11 +125,13 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
 {
 	unsigned long replaced;
 
-	if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
-		return -EFAULT;
+	if (old) {

So, we're using the instruction value '0' to mean that we don't want to
check?  Wouldn'it it be better to pass a flag in to indicate this instead
of creating a magic value?

OK.  I think you applied this patch as-is anyway, so here is a follow-on
patch:

I'd still much prefer it to be part of the original patch.  I can replace
the patch I've merged or augment it with another patch - whichever way
you prefer.