linux-kernel - [PATCH] ALSA: pcmtest: Extend error injection, decrease buffer filling overhead

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Date:   Wed, 12 Jul 2023 23:13:25 +0400
From:   Ivan Orlov <ivan.orlov0322@...il.com>
To:     perex@...ex.cz, tiwai@...e.com
Cc:     Ivan Orlov <ivan.orlov0322@...il.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] ALSA: pcmtest: Extend error injection, decrease buffer filling overhead

Extend 'pcmtest' virtual driver with 'open' callback error injection
functionality, as it already can inject errors into other PCM callbacks.

Fix the driver to use already defined variables where it is possible.

Additionally, decrease the buffer filling overhead with conditional
reminder calculation in the 'inc_buf_pos' inline function.

Signed-off-by: Ivan Orlov <ivan.orlov0322@...il.com>
---
 sound/drivers/pcmtest.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
index 291e7fe47893..08e14b5eb772 100644
--- a/sound/drivers/pcmtest.c
+++ b/sound/drivers/pcmtest.c
@@ -65,6 +65,7 @@ static int inject_delay;
 static bool inject_hwpars_err;
 static bool inject_prepare_err;
 static bool inject_trigger_err;
+static bool inject_open_err;
 
 static short fill_mode = FILL_MODE_PAT;
 
@@ -88,6 +89,9 @@ module_param(inject_prepare_err, bool, 0600);
 MODULE_PARM_DESC(inject_prepare_err, "Inject EINVAL error in the 'prepare' callback");
 module_param(inject_trigger_err, bool, 0600);
 MODULE_PARM_DESC(inject_trigger_err, "Inject EINVAL error in the 'trigger' callback");
+module_param(inject_open_err, bool, 0600);
+MODULE_PARM_DESC(inject_open_err, "Inject EBUSY error in the 'open' callback");
+
 
 struct pcmtst {
 	struct snd_pcm *pcm;
@@ -140,7 +144,8 @@ static inline void inc_buf_pos(struct pcmtst_buf_iter *v_iter, size_t by, size_t
 {
 	v_iter->total_bytes += by;
 	v_iter->buf_pos += by;
-	v_iter->buf_pos %= bytes;
+	if (v_iter->buf_pos >= bytes)
+		v_iter->buf_pos %= bytes;
 }
 
 /*
@@ -196,10 +201,10 @@ static void check_buf_block_ni(struct pcmtst_buf_iter *v_iter, struct snd_pcm_ru
 	u8 current_byte;
 
 	for (i = 0; i < v_iter->b_rw; i++) {
-		current_byte = runtime->dma_area[buf_pos_n(v_iter, channels, i % channels)];
+		ch_num = i % channels;
+		current_byte = runtime->dma_area[buf_pos_n(v_iter, channels, ch_num)];
 		if (!current_byte)
 			break;
-		ch_num = i % channels;
 		if (current_byte != patt_bufs[ch_num].buf[(v_iter->total_bytes / channels)
 							  % patt_bufs[ch_num].len]) {
 			v_iter->is_buf_corrupted = true;
@@ -239,7 +244,7 @@ static void fill_block_pattern_n(struct pcmtst_buf_iter *v_iter, struct snd_pcm_
 
 	for (i = 0; i < v_iter->b_rw; i++) {
 		ch_num = i % channels;
-		runtime->dma_area[buf_pos_n(v_iter, channels, i % channels)] =
+		runtime->dma_area[buf_pos_n(v_iter, channels, ch_num)] =
 			patt_bufs[ch_num].buf[(v_iter->total_bytes / channels)
 					      % patt_bufs[ch_num].len];
 		inc_buf_pos(v_iter, 1, runtime->dma_bytes);
@@ -364,6 +369,9 @@ static int snd_pcmtst_pcm_open(struct snd_pcm_substream *substream)
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct pcmtst_buf_iter *v_iter;
 
+	if (inject_open_err)
+		return -EBUSY;
+
 	v_iter = kzalloc(sizeof(*v_iter), GFP_KERNEL);
 	if (!v_iter)
 		return -ENOMEM;
-- 
2.34.1