Re: Missing put_cpu() in arch/ia64/sn/kernel/sn2/sn_hwperf.c?

[Tony Luck]

On Mon, Aug 8, 2011 at 11:05 AM, Thomas Meyer <thomas@xxxxxxxx> wrote:
> The function sn_hwperf_op_cpu() seems to miss a corresponding put_cpu().
>
> Or is this done in another function? I didn't find it.

It would be hard to do it elsewhere - this function may not have done
a get_cpu() [in the cpu == SN_HWPERF_ARG_ANY_CPU case].

The logic is a bit tortuous here ... perhaps simpler to split the tests
up.  Does the attached patch look right?

-Tony
diff --git a/arch/ia64/sn/kernel/sn2/sn_hwperf.c b/arch/ia64/sn/kernel/sn2/sn_hwperf.c
index 30862c0..2de41d4 100644
--- a/arch/ia64/sn/kernel/sn2/sn_hwperf.c
+++ b/arch/ia64/sn/kernel/sn2/sn_hwperf.c
@@ -615,11 +615,15 @@ static int sn_hwperf_op_cpu(struct sn_hwperf_op_info *op_info)
 		}
 	}
 
-	if (cpu == SN_HWPERF_ARG_ANY_CPU || cpu == get_cpu()) {
-		/* don't care, or already on correct cpu */
+	if (cpu == SN_HWPERF_ARG_ANY_CPU) {
+		/* don't care which cpu */
 		sn_hwperf_call_sal(op_info);
-	}
-	else {
+	} else if (cpu == get_cpu()) {
+		/* already on correct cpu */
+		sn_hwperf_call_sal(op_info);
+		put_cpu();
+	} else {
+		put_cpu();
 		if (use_ipi) {
 			/* use an interprocessor interrupt to call SAL */
 			smp_call_function_single(cpu, sn_hwperf_call_sal,