[PATCH v3 2/7] ALSA: pcmtest: Fix leak at probe error

[Takashi Iwai <tiwai@suse.de>]

When an error happens at probe of pcmtest driver before
snd_card_register() succeeds, we have to release the card explicitly,
but it's not done, leading to a potential memory leak.

Also, pcmtest driver manages struct pcmtst object unnecessarily
complicatedly by a dynamic allocation and release.

This patch fixes and cleans up the resource management:
- Use card's private_data allocation for struct sndpcmtst at the card
  creation, which is released automatically together with the card
- Since the allocation of pcmtest is gone, snd_pcmtst_create() is
  rather pointless, so just directly calling snd_pcmtst_new_pcm()
- Use the new auto-clean mechanism to handle the error case at probe.
- Many release handlers became superfluous and dropped

In the end we got a good amount of code reduction.

Fixes: 315a3d57c64c ("ALSA: Implement the new Virtual PCM Test Driver")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/drivers/pcmtest.c | 66 +++++++----------------------------------
 1 file changed, 10 insertions(+), 56 deletions(-)

diff --git a/sound/drivers/pcmtest.c b/sound/drivers/pcmtest.c
index fea9580593e6..b4e333b4c438 100644
--- a/sound/drivers/pcmtest.c
+++ b/sound/drivers/pcmtest.c
@@ -446,20 +446,6 @@ static snd_pcm_uframes_t snd_pcmtst_pcm_pointer(struct snd_pcm_substream *substr
 	return bytes_to_frames(substream->runtime, v_iter->buf_pos);
 }
 
-static int snd_pcmtst_free(struct pcmtst *pcmtst)
-{
-	if (!pcmtst)
-		return 0;
-	kfree(pcmtst);
-	return 0;
-}
-
-// These callbacks are required, but empty - all freeing occurs in pdev_remove
-static int snd_pcmtst_dev_free(struct snd_device *device)
-{
-	return 0;
-}
-
 static void pcmtst_pdev_release(struct device *dev)
 {
 }
@@ -563,40 +549,9 @@ static int snd_pcmtst_new_pcm(struct pcmtst *pcmtst)
 	return err;
 }
 
-static int snd_pcmtst_create(struct snd_card *card, struct platform_device *pdev,
-			     struct pcmtst **r_pcmtst)
-{
-	struct pcmtst *pcmtst;
-	int err;
-	static const struct snd_device_ops ops = {
-		.dev_free = snd_pcmtst_dev_free,
-	};
-
-	pcmtst = kzalloc_obj(*pcmtst);
-	if (!pcmtst)
-		return -ENOMEM;
-	pcmtst->card = card;
-	pcmtst->pdev = pdev;
-
-	err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, pcmtst, &ops);
-	if (err < 0)
-		goto _err_free_chip;
-
-	err = snd_pcmtst_new_pcm(pcmtst);
-	if (err < 0)
-		goto _err_free_chip;
-
-	*r_pcmtst = pcmtst;
-	return 0;
-
-_err_free_chip:
-	snd_pcmtst_free(pcmtst);
-	return err;
-}
-
 static int pcmtst_probe(struct platform_device *pdev)
 {
-	struct snd_card *card;
+	struct snd_card *card __free(snd_card_free) = NULL;
 	struct pcmtst *pcmtst;
 	int err;
 
@@ -604,10 +559,16 @@ static int pcmtst_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	err = snd_devm_card_new(&pdev->dev, index, id, THIS_MODULE, 0, &card);
+	err = snd_devm_card_new(&pdev->dev, index, id, THIS_MODULE,
+				sizeof(*pcmtst), &card);
 	if (err < 0)
 		return err;
-	err = snd_pcmtst_create(card, pdev, &pcmtst);
+
+	pcmtst = card->private_data;
+	pcmtst->card = card;
+	pcmtst->pdev = pdev;
+
+	err = snd_pcmtst_new_pcm(pcmtst);
 	if (err < 0)
 		return err;
 
@@ -620,17 +581,11 @@ static int pcmtst_probe(struct platform_device *pdev)
 		return err;
 
 	platform_set_drvdata(pdev, pcmtst);
+	card = NULL; /* probe succeeded, don't release as error */
 
 	return 0;
 }
 
-static void pdev_remove(struct platform_device *pdev)
-{
-	struct pcmtst *pcmtst = platform_get_drvdata(pdev);
-
-	snd_pcmtst_free(pcmtst);
-}
-
 static struct platform_device pcmtst_pdev = {
 	.name =		"pcmtest",
 	.dev.release =	pcmtst_pdev_release,
@@ -638,7 +593,6 @@ static struct platform_device pcmtst_pdev = {
 
 static struct platform_driver pcmtst_pdrv = {
 	.probe =	pcmtst_probe,
-	.remove =	pdev_remove,
 	.driver =	{
 		.name = "pcmtest",
 	},
-- 
2.55.0