[PATCH 2/3] selftests: ALSA: pcmtest: Test errors from the PCM callbacks

[HyeongJun An <sammiee5311@gmail.com>]

The driver can return an error from its open, hw_params, prepare and
trigger callbacks, controlled by the inject_*_err module parameters.
No test uses them, so nothing checks that these errors reach user space.

Add a test for each callback. It sets the parameter, checks that the
matching call fails with the driver's error, then clears the parameter
and checks that the call succeeds. The trigger test also checks that a
failed start leaves the stream in the PREPARED state. The fixture
teardown clears all parameters, so a failed test does not affect the
next one.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: HyeongJun An <sammiee5311@gmail.com>
---
 .../selftests/alsa/test-pcmtest-driver.c      | 89 +++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/tools/testing/selftests/alsa/test-pcmtest-driver.c b/tools/testing/selftests/alsa/test-pcmtest-driver.c
index fc4d12542808..380364ee7924 100644
--- a/tools/testing/selftests/alsa/test-pcmtest-driver.c
+++ b/tools/testing/selftests/alsa/test-pcmtest-driver.c
@@ -5,6 +5,7 @@
  *
  * Copyright 2023 Ivan Orlov <ivan.orlov0322@gmail.com>
  */
+#include <errno.h>
 #include <string.h>
 #include <alsa/asoundlib.h>
 #include "kselftest_harness.h"
@@ -58,6 +59,20 @@ static int read_patterns(void)
 	return 0;
 }
 
+static int set_param(const char *name, int value)
+{
+	char path[128];
+	FILE *f;
+
+	sprintf(path, "/sys/module/snd_pcmtest/parameters/%s", name);
+	f = fopen(path, "w");
+	if (!f)
+		return -1;
+	fprintf(f, "%d", value);
+
+	return fclose(f) ? -1 : 0;
+}
+
 static int get_test_results(char *debug_name)
 {
 	int result;
@@ -141,6 +156,10 @@ FIXTURE(pcmtest) {
 };
 
 FIXTURE_TEARDOWN(pcmtest) {
+	set_param("inject_open_err", 0);
+	set_param("inject_hwpars_err", 0);
+	set_param("inject_prepare_err", 0);
+	set_param("inject_trigger_err", 0);
 }
 
 FIXTURE_SETUP(pcmtest) {
@@ -343,4 +362,74 @@ TEST_F(pcmtest, reset_ioctl) {
 	snd_pcm_close(handle);
 }
 
+/*
+ * Here we check that an error from each PCM callback reaches user space. The driver returns
+ * the error while the matching 'inject_*_err' parameter is set, and works again once it is
+ * cleared.
+ */
+TEST_F(pcmtest, open_err) {
+	snd_pcm_t *handle;
+	char pcm_name[32];
+
+	sprintf(pcm_name, "hw:%d,0,0", self->card);
+
+	ASSERT_EQ(set_param("inject_open_err", 1), 0);
+	ASSERT_EQ(snd_pcm_open(&handle, pcm_name, SND_PCM_STREAM_PLAYBACK, 0), -EBUSY);
+
+	ASSERT_EQ(set_param("inject_open_err", 0), 0);
+	ASSERT_EQ(snd_pcm_open(&handle, pcm_name, SND_PCM_STREAM_PLAYBACK, 0), 0);
+	snd_pcm_close(handle);
+}
+
+TEST_F(pcmtest, hw_params_err) {
+	snd_pcm_t *handle;
+	char pcm_name[32];
+
+	snd_pcm_hw_params_alloca(&self->hwparams);
+	sprintf(pcm_name, "hw:%d,0,0", self->card);
+	ASSERT_EQ(snd_pcm_open(&handle, pcm_name, SND_PCM_STREAM_PLAYBACK, 0), 0);
+	ASSERT_EQ(snd_pcm_hw_params_any(handle, self->hwparams), 0);
+
+	ASSERT_EQ(set_param("inject_hwpars_err", 1), 0);
+	ASSERT_EQ(snd_pcm_hw_params(handle, self->hwparams), -EBUSY);
+
+	ASSERT_EQ(set_param("inject_hwpars_err", 0), 0);
+	ASSERT_EQ(snd_pcm_hw_params(handle, self->hwparams), 0);
+	snd_pcm_close(handle);
+}
+
+TEST_F(pcmtest, prepare_err) {
+	snd_pcm_t *handle;
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, &self->params,
+			       self->card, SND_PCM_STREAM_PLAYBACK), 0);
+
+	ASSERT_EQ(set_param("inject_prepare_err", 1), 0);
+	ASSERT_EQ(snd_pcm_prepare(handle), -EINVAL);
+
+	ASSERT_EQ(set_param("inject_prepare_err", 0), 0);
+	ASSERT_EQ(snd_pcm_prepare(handle), 0);
+	snd_pcm_close(handle);
+}
+
+TEST_F(pcmtest, trigger_err) {
+	snd_pcm_t *handle;
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, &self->params,
+			       self->card, SND_PCM_STREAM_CAPTURE), 0);
+
+	ASSERT_EQ(set_param("inject_trigger_err", 1), 0);
+	ASSERT_EQ(snd_pcm_start(handle), -EINVAL);
+	ASSERT_EQ(snd_pcm_state(handle), SND_PCM_STATE_PREPARED);
+
+	ASSERT_EQ(set_param("inject_trigger_err", 0), 0);
+	ASSERT_EQ(snd_pcm_start(handle), 0);
+	ASSERT_EQ(snd_pcm_state(handle), SND_PCM_STATE_RUNNING);
+	snd_pcm_close(handle);
+}
+
 TEST_HARNESS_MAIN
-- 
2.43.0