[kvm-unit-tests PATCH 08/10] arm/arm64: gic: Split check_acked() into two functions

[Alexandru Elisei <alexandru.elisei@arm.com>]

check_acked() has several peculiarities: is the only function among the
check_* functions which calls report() directly, it does two things
(waits for interrupts and checks for misfired interrupts) and it also
mixes printf, report_info and report calls.

check_acked() also reports a pass and returns as soon all the target CPUs
have received interrupts, However, a CPU not having received an interrupt
*now* does not guarantee not receiving an eroneous interrupt if we wait
long enough.

Rework the function by splitting it into two separate functions, each with
a single responsability: wait_for_interrupts(), which waits for the
expected interrupts to fire, and check_acked() which checks that interrupts
have been received as expected.

wait_for_interrupts() also waits an extra 100 milliseconds after the
expected interrupts have been received in an effort to make sure we don't
miss misfiring interrupts.

Splitting check_acked() into two functions will also allow us to
customize the behavior of each function in the future more easily
without using an unnecessarily long list of arguments for check_acked().

CC: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arm/gic.c | 73 +++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 47 insertions(+), 26 deletions(-)

diff --git a/arm/gic.c b/arm/gic.c
index 544c283f5f47..dcdab7d5f39a 100644
--- a/arm/gic.c
+++ b/arm/gic.c
@@ -62,41 +62,42 @@ static void stats_reset(void)
 	}
 }
 
-static void check_acked(const char *testname, cpumask_t *mask)
+static void wait_for_interrupts(cpumask_t *mask)
 {
-	int missing = 0, extra = 0, unexpected = 0;
 	int nr_pass, cpu, i;
-	bool bad = false;
 
 	/* Wait up to 5s for all interrupts to be delivered */
-	for (i = 0; i < 50; ++i) {
+	for (i = 0; i < 50; i++) {
 		mdelay(100);
 		nr_pass = 0;
 		for_each_present_cpu(cpu) {
+			/*
+			 * A CPU having receied more than one interrupts will
+			 * show up in check_acked(), and no matter how long we
+			 * wait it cannot un-receive it. Consier at least one
+			 * interrupt as a pass.
+			 */
 			nr_pass += cpumask_test_cpu(cpu, mask) ?
-				acked[cpu] == 1 : acked[cpu] == 0;
-			smp_rmb(); /* pairs with smp_wmb in ipi_handler */
-
-			if (bad_sender[cpu] != -1) {
-				printf("cpu%d received IPI from wrong sender %d\n",
-					cpu, bad_sender[cpu]);
-				bad = true;
-			}
-
-			if (bad_irq[cpu] != -1) {
-				printf("cpu%d received wrong irq %d\n",
-					cpu, bad_irq[cpu]);
-				bad = true;
-			}
+				acked[cpu] >= 1 : acked[cpu] == 0;
 		}
+
 		if (nr_pass == nr_cpus) {
-			report(!bad, "%s", testname);
 			if (i)
-				report_info("took more than %d ms", i * 100);
+				report_info("interrupts took more than %d ms", i * 100);
+			mdelay(100);
 			return;
 		}
 	}
 
+	report_info("interrupts timed-out (5s)");
+}
+
+static bool check_acked(cpumask_t *mask)
+{
+	int missing = 0, extra = 0, unexpected = 0;
+	bool pass = true;
+	int cpu;
+
 	for_each_present_cpu(cpu) {
 		if (cpumask_test_cpu(cpu, mask)) {
 			if (!acked[cpu])
@@ -107,11 +108,28 @@ static void check_acked(const char *testname, cpumask_t *mask)
 			if (acked[cpu])
 				++unexpected;
 		}
+		smp_rmb(); /* pairs with smp_wmb in ipi_handler */
+
+		if (bad_sender[cpu] != -1) {
+			report_info("cpu%d received IPI from wrong sender %d",
+					cpu, bad_sender[cpu]);
+			pass = false;
+		}
+
+		if (bad_irq[cpu] != -1) {
+			report_info("cpu%d received wrong irq %d",
+					cpu, bad_irq[cpu]);
+			pass = false;
+		}
+	}
+
+	if (missing || extra || unexpected) {
+		report_info("ACKS: missing=%d extra=%d unexpected=%d",
+				missing, extra, unexpected);
+		pass = false;
 	}
 
-	report(false, "%s", testname);
-	report_info("Timed-out (5s). ACKS: missing=%d extra=%d unexpected=%d",
-		    missing, extra, unexpected);
+	return pass;
 }
 
 static void check_spurious(void)
@@ -300,7 +318,8 @@ static void ipi_test_self(void)
 	cpumask_clear(&mask);
 	cpumask_set_cpu(smp_processor_id(), &mask);
 	gic->ipi.send_self();
-	check_acked("IPI: self", &mask);
+	wait_for_interrupts(&mask);
+	report(check_acked(&mask), "Interrupts received");
 	report_prefix_pop();
 }
 
@@ -315,7 +334,8 @@ static void ipi_test_smp(void)
 	for (i = smp_processor_id() & 1; i < nr_cpus; i += 2)
 		cpumask_clear_cpu(i, &mask);
 	gic_ipi_send_mask(IPI_IRQ, &mask);
-	check_acked("IPI: directed", &mask);
+	wait_for_interrupts(&mask);
+	report(check_acked(&mask), "Interrupts received");
 	report_prefix_pop();
 
 	report_prefix_push("broadcast");
@@ -323,7 +343,8 @@ static void ipi_test_smp(void)
 	cpumask_copy(&mask, &cpu_present_mask);
 	cpumask_clear_cpu(smp_processor_id(), &mask);
 	gic->ipi.send_broadcast();
-	check_acked("IPI: broadcast", &mask);
+	wait_for_interrupts(&mask);
+	report(check_acked(&mask), "Interrupts received");
 	report_prefix_pop();
 }
 
-- 
2.29.2