[PATCH v2 0/5] usb: gadget: audio fixes and clean ups

[PATCH v2 0/5] usb: gadget: audio fixes and clean ups

[Jerome Brunet]

This patchset is a collection of fixes and clean ups found while
working on the uac2 gadget. Details are provided in each change.

Changes since v1: [1]
 * Jack's patch added to the series (no more deps)
 * Warning [2] on Patch 3 fixed

[1]: https://lore.kernel.org/r/20201221173531.215169-1-jbrunet@baylibre.com
[2]: https://lore.kernel.org/r/202012291638.QiDQi3Gs-lkp@intel.com

Jack Pham (1):
  usb: gadget: u_audio: Free requests only after callback

Jerome Brunet (4):
  usb: gadget: f_uac2: reset wMaxPacketSize
  usb: gadget: u_audio: factorize ssize to alsa fmt conversion
  usb: gadget: u_audio: remove struct uac_req
  usb: gadget: u_audio: clean up locking

 drivers/usb/gadget/function/f_uac2.c  |  69 +++++++++++---
 drivers/usb/gadget/function/u_audio.c | 130 +++++++++++---------------
 2 files changed, 112 insertions(+), 87 deletions(-)

-- 
2.29.2

[PATCH v2 1/5] usb: gadget: u_audio: Free requests only after callback

[Jerome Brunet]

From: Jack Pham <jackp@codeaurora.org>

As per the kernel doc for usb_ep_dequeue(), it states that "this
routine is asynchronous, that is, it may return before the completion
routine runs". And indeed since v5.0 the dwc3 gadget driver updated
its behavior to place dequeued requests on to a cancelled list to be
given back later after the endpoint is stopped.

The free_ep() was incorrectly assuming that a request was ready to
be freed after calling dequeue which results in a use-after-free
in dwc3 when it traverses its cancelled list. Fix this by moving
the usb_ep_free_request() call to the callback itself in case the
ep is disabled.

Fixes: eb9fecb9e69b0 ("usb: gadget: f_uac2: split out audio core")
Reported-and-tested-by: Ferry Toth <fntoth@gmail.com>
Reviewed-and-tested-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/usb/gadget/function/u_audio.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index e6d32c536781..71dd9f16c246 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -89,7 +89,12 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
 	struct snd_uac_chip *uac = prm->uac;
 
 	/* i/f shutting down */
-	if (!prm->ep_enabled || req->status == -ESHUTDOWN)
+	if (!prm->ep_enabled) {
+		usb_ep_free_request(ep, req);
+		return;
+	}
+
+	if (req->status == -ESHUTDOWN)
 		return;
 
 	/*
@@ -336,8 +341,9 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
 
 	for (i = 0; i < params->req_number; i++) {
 		if (prm->ureq[i].req) {
-			usb_ep_dequeue(ep, prm->ureq[i].req);
-			usb_ep_free_request(ep, prm->ureq[i].req);
+			if (usb_ep_dequeue(ep, prm->ureq[i].req))
+				usb_ep_free_request(ep, prm->ureq[i].req);
+			/* else will be freed in u_audio_iso_complete() */
 			prm->ureq[i].req = NULL;
 		}
 	}
-- 
2.29.2

Re: [PATCH v2 1/5] usb: gadget: u_audio: Free requests only after callback

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 1634 bytes --]

Jerome Brunet <jbrunet@baylibre.com> writes:

> From: Jack Pham <jackp@codeaurora.org>
>
> As per the kernel doc for usb_ep_dequeue(), it states that "this
> routine is asynchronous, that is, it may return before the completion
> routine runs". And indeed since v5.0 the dwc3 gadget driver updated
> its behavior to place dequeued requests on to a cancelled list to be
> given back later after the endpoint is stopped.
>
> The free_ep() was incorrectly assuming that a request was ready to
> be freed after calling dequeue which results in a use-after-free
> in dwc3 when it traverses its cancelled list. Fix this by moving
> the usb_ep_free_request() call to the callback itself in case the
> ep is disabled.
>
> Fixes: eb9fecb9e69b0 ("usb: gadget: f_uac2: split out audio core")
> Reported-and-tested-by: Ferry Toth <fntoth@gmail.com>
> Reviewed-and-tested-by: Peter Chen <peter.chen@nxp.com>
> Signed-off-by: Jack Pham <jackp@codeaurora.org>
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Looks good to me, just one comment below:

> @@ -336,8 +341,9 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
>  
>  	for (i = 0; i < params->req_number; i++) {
>  		if (prm->ureq[i].req) {
> -			usb_ep_dequeue(ep, prm->ureq[i].req);
> -			usb_ep_free_request(ep, prm->ureq[i].req);
> +			if (usb_ep_dequeue(ep, prm->ureq[i].req))
> +				usb_ep_free_request(ep, prm->ureq[i].req);

do you mind adding a comment here stating that this is coping with a
possible error during usb_ep_dequeue()?

Other than that:

Acked-by: Felipe Balbi <balbi@kernel.org>

-- 
balbi

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[PATCH v2 2/5] usb: gadget: f_uac2: reset wMaxPacketSize

[Jerome Brunet]

With commit 913e4a90b6f9 ("usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth")
wMaxPacketSize is computed dynamically but the value is never reset.

Because of this, the actual maximum packet size can only decrease each time
the audio gadget is instantiated.

Reset the endpoint maximum packet size and mark wMaxPacketSize as dynamic
to solve the problem.

Fixes: 913e4a90b6f9 ("usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/usb/gadget/function/f_uac2.c | 69 ++++++++++++++++++++++------
 1 file changed, 55 insertions(+), 14 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 3633df6d7610..5d960b6603b6 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -271,7 +271,7 @@ static struct usb_endpoint_descriptor fs_epout_desc = {
 
 	.bEndpointAddress = USB_DIR_OUT,
 	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
-	.wMaxPacketSize = cpu_to_le16(1023),
+	/* .wMaxPacketSize = DYNAMIC */
 	.bInterval = 1,
 };
 
@@ -280,7 +280,7 @@ static struct usb_endpoint_descriptor hs_epout_desc = {
 	.bDescriptorType = USB_DT_ENDPOINT,
 
 	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
-	.wMaxPacketSize = cpu_to_le16(1024),
+	/* .wMaxPacketSize = DYNAMIC */
 	.bInterval = 4,
 };
 
@@ -348,7 +348,7 @@ static struct usb_endpoint_descriptor fs_epin_desc = {
 
 	.bEndpointAddress = USB_DIR_IN,
 	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
-	.wMaxPacketSize = cpu_to_le16(1023),
+	/* .wMaxPacketSize = DYNAMIC */
 	.bInterval = 1,
 };
 
@@ -357,7 +357,7 @@ static struct usb_endpoint_descriptor hs_epin_desc = {
 	.bDescriptorType = USB_DT_ENDPOINT,
 
 	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
-	.wMaxPacketSize = cpu_to_le16(1024),
+	/* .wMaxPacketSize = DYNAMIC */
 	.bInterval = 4,
 };
 
@@ -444,12 +444,28 @@ struct cntrl_range_lay3 {
 	__le32	dRES;
 } __packed;
 
-static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
+static int set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 	struct usb_endpoint_descriptor *ep_desc,
-	unsigned int factor, bool is_playback)
+	enum usb_device_speed speed, bool is_playback)
 {
 	int chmask, srate, ssize;
-	u16 max_packet_size;
+	u16 max_size_bw, max_size_ep;
+	unsigned int factor;
+
+	switch (speed) {
+	case USB_SPEED_FULL:
+		max_size_ep = 1023;
+		factor = 1000;
+		break;
+
+	case USB_SPEED_HIGH:
+		max_size_ep = 1024;
+		factor = 8000;
+		break;
+
+	default:
+		return -EINVAL;
+	}
 
 	if (is_playback) {
 		chmask = uac2_opts->p_chmask;
@@ -461,10 +477,12 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 		ssize = uac2_opts->c_ssize;
 	}
 
-	max_packet_size = num_channels(chmask) * ssize *
+	max_size_bw = num_channels(chmask) * ssize *
 		DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1)));
-	ep_desc->wMaxPacketSize = cpu_to_le16(min_t(u16, max_packet_size,
-				le16_to_cpu(ep_desc->wMaxPacketSize)));
+	ep_desc->wMaxPacketSize = cpu_to_le16(min_t(u16, max_size_bw,
+						    max_size_ep));
+
+	return 0;
 }
 
 /* Use macro to overcome line length limitation */
@@ -670,10 +688,33 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
 	}
 
 	/* Calculate wMaxPacketSize according to audio bandwidth */
-	set_ep_max_packet_size(uac2_opts, &fs_epin_desc, 1000, true);
-	set_ep_max_packet_size(uac2_opts, &fs_epout_desc, 1000, false);
-	set_ep_max_packet_size(uac2_opts, &hs_epin_desc, 8000, true);
-	set_ep_max_packet_size(uac2_opts, &hs_epout_desc, 8000, false);
+	ret = set_ep_max_packet_size(uac2_opts, &fs_epin_desc, USB_SPEED_FULL,
+				     true);
+	if (ret < 0) {
+		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
+
+	ret = set_ep_max_packet_size(uac2_opts, &fs_epout_desc, USB_SPEED_FULL,
+				     false);
+	if (ret < 0) {
+		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
+
+	ret = set_ep_max_packet_size(uac2_opts, &hs_epin_desc, USB_SPEED_HIGH,
+				     true);
+	if (ret < 0) {
+		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
+
+	ret = set_ep_max_packet_size(uac2_opts, &hs_epout_desc, USB_SPEED_HIGH,
+				     false);
+	if (ret < 0) {
+		dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
 
 	if (EPOUT_EN(uac2_opts)) {
 		agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
-- 
2.29.2

Re: [PATCH v2 2/5] usb: gadget: f_uac2: reset wMaxPacketSize

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 656 bytes --]


Jerome Brunet <jbrunet@baylibre.com> writes:
> With commit 913e4a90b6f9 ("usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth")
> wMaxPacketSize is computed dynamically but the value is never reset.
>
> Because of this, the actual maximum packet size can only decrease each time
> the audio gadget is instantiated.
>
> Reset the endpoint maximum packet size and mark wMaxPacketSize as dynamic
> to solve the problem.
>
> Fixes: 913e4a90b6f9 ("usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth")
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Acked-by: Felipe Balbi <balbi@kernel.org>

-- 
balbi

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[PATCH v2 3/5] usb: gadget: u_audio: factorize ssize to alsa fmt conversion

[Jerome Brunet]

Factorize format related code common to the capture and playback path.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/usb/gadget/function/u_audio.c | 43 +++++++++++++--------------
 1 file changed, 21 insertions(+), 22 deletions(-)

diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index 71dd9f16c246..045f237472a7 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -244,6 +244,25 @@ static snd_pcm_uframes_t uac_pcm_pointer(struct snd_pcm_substream *substream)
 	return bytes_to_frames(substream->runtime, prm->hw_ptr);
 }
 
+static u64 uac_ssize_to_fmt(int ssize)
+{
+	u64 ret;
+
+	switch (ssize) {
+	case 3:
+		ret = SNDRV_PCM_FMTBIT_S24_3LE;
+		break;
+	case 4:
+		ret = SNDRV_PCM_FMTBIT_S32_LE;
+		break;
+	default:
+		ret = SNDRV_PCM_FMTBIT_S16_LE;
+		break;
+	}
+
+	return ret;
+}
+
 static int uac_pcm_open(struct snd_pcm_substream *substream)
 {
 	struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
@@ -269,34 +288,14 @@ static int uac_pcm_open(struct snd_pcm_substream *substream)
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		spin_lock_init(&uac->p_prm.lock);
 		runtime->hw.rate_min = p_srate;
-		switch (p_ssize) {
-		case 3:
-			runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
-			break;
-		case 4:
-			runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
-			break;
-		default:
-			runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
-			break;
-		}
+		runtime->hw.formats = uac_ssize_to_fmt(p_ssize);
 		runtime->hw.channels_min = num_channels(p_chmask);
 		runtime->hw.period_bytes_min = 2 * uac->p_prm.max_psize
 						/ runtime->hw.periods_min;
 	} else {
 		spin_lock_init(&uac->c_prm.lock);
 		runtime->hw.rate_min = c_srate;
-		switch (c_ssize) {
-		case 3:
-			runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
-			break;
-		case 4:
-			runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
-			break;
-		default:
-			runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
-			break;
-		}
+		runtime->hw.formats = uac_ssize_to_fmt(c_ssize);
 		runtime->hw.channels_min = num_channels(c_chmask);
 		runtime->hw.period_bytes_min = 2 * uac->c_prm.max_psize
 						/ runtime->hw.periods_min;
-- 
2.29.2

Re: [PATCH v2 3/5] usb: gadget: u_audio: factorize ssize to alsa fmt conversion

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 392 bytes --]

Jerome Brunet <jbrunet@baylibre.com> writes:

> Factorize format related code common to the capture and playback path.
>
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

It's never a good idea to send fixes and cleanups/refactors in the same
series as that can confuse the person applying your changes.

In any case:

Acked-by: Felipe Balbi <balbi@kernel.org>

-- 
balbi

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[PATCH v2 4/5] usb: gadget: u_audio: remove struct uac_req

[Jerome Brunet]

'struct uac_req' purpose is to link 'struct usb_request' to the
corresponding 'struct uac_rtd_params'. However member req is never
used. Using the context of the usb request, we can keep track of the
corresponding 'struct uac_rtd_params' just as well, without allocating
extra memory.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/usb/gadget/function/u_audio.c | 58 ++++++++++++---------------
 1 file changed, 26 insertions(+), 32 deletions(-)

diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index 045f237472a7..1d12657b3b73 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -23,11 +23,6 @@
 #define PRD_SIZE_MAX	PAGE_SIZE
 #define MIN_PERIODS	4
 
-struct uac_req {
-	struct uac_rtd_params *pp; /* parent param */
-	struct usb_request *req;
-};
-
 /* Runtime data params for one stream */
 struct uac_rtd_params {
 	struct snd_uac_chip *uac; /* parent chip */
@@ -41,7 +36,7 @@ struct uac_rtd_params {
 	void *rbuf;
 
 	unsigned int max_psize;	/* MaxPacketSize of endpoint */
-	struct uac_req *ureq;
+	struct usb_request **reqs;
 
 	spinlock_t lock;
 };
@@ -82,10 +77,9 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
 	unsigned long flags, flags2;
 	unsigned int hw_ptr;
 	int status = req->status;
-	struct uac_req *ur = req->context;
 	struct snd_pcm_substream *substream;
 	struct snd_pcm_runtime *runtime;
-	struct uac_rtd_params *prm = ur->pp;
+	struct uac_rtd_params *prm = req->context;
 	struct snd_uac_chip *uac = prm->uac;
 
 	/* i/f shutting down */
@@ -339,11 +333,11 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
 	params = &audio_dev->params;
 
 	for (i = 0; i < params->req_number; i++) {
-		if (prm->ureq[i].req) {
-			if (usb_ep_dequeue(ep, prm->ureq[i].req))
-				usb_ep_free_request(ep, prm->ureq[i].req);
+		if (prm->reqs[i]) {
+			if (usb_ep_dequeue(ep, prm->reqs[i]))
+				usb_ep_free_request(ep, prm->reqs[i]);
 			/* else will be freed in u_audio_iso_complete() */
-			prm->ureq[i].req = NULL;
+			prm->reqs[i] = NULL;
 		}
 	}
 
@@ -372,22 +366,21 @@ int u_audio_start_capture(struct g_audio *audio_dev)
 	usb_ep_enable(ep);
 
 	for (i = 0; i < params->req_number; i++) {
-		if (!prm->ureq[i].req) {
+		if (!prm->reqs[i]) {
 			req = usb_ep_alloc_request(ep, GFP_ATOMIC);
 			if (req == NULL)
 				return -ENOMEM;
 
-			prm->ureq[i].req = req;
-			prm->ureq[i].pp = prm;
+			prm->reqs[i] = req;
 
 			req->zero = 0;
-			req->context = &prm->ureq[i];
+			req->context = prm;
 			req->length = req_len;
 			req->complete = u_audio_iso_complete;
 			req->buf = prm->rbuf + i * ep->maxpacket;
 		}
 
-		if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+		if (usb_ep_queue(ep, prm->reqs[i], GFP_ATOMIC))
 			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
 	}
 
@@ -450,22 +443,21 @@ int u_audio_start_playback(struct g_audio *audio_dev)
 	usb_ep_enable(ep);
 
 	for (i = 0; i < params->req_number; i++) {
-		if (!prm->ureq[i].req) {
+		if (!prm->reqs[i]) {
 			req = usb_ep_alloc_request(ep, GFP_ATOMIC);
 			if (req == NULL)
 				return -ENOMEM;
 
-			prm->ureq[i].req = req;
-			prm->ureq[i].pp = prm;
+			prm->reqs[i] = req;
 
 			req->zero = 0;
-			req->context = &prm->ureq[i];
+			req->context = prm;
 			req->length = req_len;
 			req->complete = u_audio_iso_complete;
 			req->buf = prm->rbuf + i * ep->maxpacket;
 		}
 
-		if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+		if (usb_ep_queue(ep, prm->reqs[i], GFP_ATOMIC))
 			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
 	}
 
@@ -510,9 +502,10 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
 		uac->c_prm.uac = uac;
 		prm->max_psize = g_audio->out_ep_maxpsize;
 
-		prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),
-				GFP_KERNEL);
-		if (!prm->ureq) {
+		prm->reqs = kcalloc(params->req_number,
+				    sizeof(struct usb_request *),
+				    GFP_KERNEL);
+		if (!prm->reqs) {
 			err = -ENOMEM;
 			goto fail;
 		}
@@ -532,9 +525,10 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
 		uac->p_prm.uac = uac;
 		prm->max_psize = g_audio->in_ep_maxpsize;
 
-		prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),
-				GFP_KERNEL);
-		if (!prm->ureq) {
+		prm->reqs = kcalloc(params->req_number,
+				    sizeof(struct usb_request *),
+				    GFP_KERNEL);
+		if (!prm->reqs) {
 			err = -ENOMEM;
 			goto fail;
 		}
@@ -587,8 +581,8 @@ int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
 snd_fail:
 	snd_card_free(card);
 fail:
-	kfree(uac->p_prm.ureq);
-	kfree(uac->c_prm.ureq);
+	kfree(uac->p_prm.reqs);
+	kfree(uac->c_prm.reqs);
 	kfree(uac->p_prm.rbuf);
 	kfree(uac->c_prm.rbuf);
 	kfree(uac);
@@ -610,8 +604,8 @@ void g_audio_cleanup(struct g_audio *g_audio)
 	if (card)
 		snd_card_free(card);
 
-	kfree(uac->p_prm.ureq);
-	kfree(uac->c_prm.ureq);
+	kfree(uac->p_prm.reqs);
+	kfree(uac->c_prm.reqs);
 	kfree(uac->p_prm.rbuf);
 	kfree(uac->c_prm.rbuf);
 	kfree(uac);
-- 
2.29.2

Re: [PATCH v2 4/5] usb: gadget: u_audio: remove struct uac_req

[Felipe Balbi]

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Jerome Brunet <jbrunet@baylibre.com> writes:

> 'struct uac_req' purpose is to link 'struct usb_request' to the
> corresponding 'struct uac_rtd_params'. However member req is never
> used. Using the context of the usb request, we can keep track of the
> corresponding 'struct uac_rtd_params' just as well, without allocating
> extra memory.
>
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Acked-by: Felipe Balbi <balbi@kernel.org>

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balbi

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[PATCH v2 5/5] usb: gadget: u_audio: clean up locking

[Jerome Brunet]

snd_pcm_stream_lock() is held when the ALSA .trigger() callback is called.
The lock of 'struct uac_rtd_params' is not necessary since all its locking
operation are done under the snd_pcm_stream_lock() too.

Also, usb_request .complete() is called with irqs disabled, so saving and
restoring the irqs is not necessary.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/usb/gadget/function/u_audio.c | 23 ++++-------------------
 1 file changed, 4 insertions(+), 19 deletions(-)

diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index 1d12657b3b73..e985630fbe6e 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -36,9 +36,8 @@ struct uac_rtd_params {
 	void *rbuf;
 
 	unsigned int max_psize;	/* MaxPacketSize of endpoint */
-	struct usb_request **reqs;
 
-	spinlock_t lock;
+	struct usb_request **reqs;
 };
 
 struct snd_uac_chip {
@@ -74,7 +73,6 @@ static const struct snd_pcm_hardware uac_pcm_hardware = {
 static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
 {
 	unsigned int pending;
-	unsigned long flags, flags2;
 	unsigned int hw_ptr;
 	int status = req->status;
 	struct snd_pcm_substream *substream;
@@ -105,16 +103,14 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
 	if (!substream)
 		goto exit;
 
-	snd_pcm_stream_lock_irqsave(substream, flags2);
+	snd_pcm_stream_lock(substream);
 
 	runtime = substream->runtime;
 	if (!runtime || !snd_pcm_running(substream)) {
-		snd_pcm_stream_unlock_irqrestore(substream, flags2);
+		snd_pcm_stream_unlock(substream);
 		goto exit;
 	}
 
-	spin_lock_irqsave(&prm->lock, flags);
-
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		/*
 		 * For each IN packet, take the quotient of the current data
@@ -141,8 +137,6 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
 
 	hw_ptr = prm->hw_ptr;
 
-	spin_unlock_irqrestore(&prm->lock, flags);
-
 	/* Pack USB load in ALSA ring buffer */
 	pending = runtime->dma_bytes - hw_ptr;
 
@@ -166,12 +160,10 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
 		}
 	}
 
-	spin_lock_irqsave(&prm->lock, flags);
 	/* update hw_ptr after data is copied to memory */
 	prm->hw_ptr = (hw_ptr + req->actual) % runtime->dma_bytes;
 	hw_ptr = prm->hw_ptr;
-	spin_unlock_irqrestore(&prm->lock, flags);
-	snd_pcm_stream_unlock_irqrestore(substream, flags2);
+	snd_pcm_stream_unlock(substream);
 
 	if ((hw_ptr % snd_pcm_lib_period_bytes(substream)) < req->actual)
 		snd_pcm_period_elapsed(substream);
@@ -187,7 +179,6 @@ static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 	struct uac_rtd_params *prm;
 	struct g_audio *audio_dev;
 	struct uac_params *params;
-	unsigned long flags;
 	int err = 0;
 
 	audio_dev = uac->audio_dev;
@@ -198,8 +189,6 @@ static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 	else
 		prm = &uac->c_prm;
 
-	spin_lock_irqsave(&prm->lock, flags);
-
 	/* Reset */
 	prm->hw_ptr = 0;
 
@@ -216,8 +205,6 @@ static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 		err = -EINVAL;
 	}
 
-	spin_unlock_irqrestore(&prm->lock, flags);
-
 	/* Clear buffer after Play stops */
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && !prm->ss)
 		memset(prm->rbuf, 0, prm->max_psize * params->req_number);
@@ -280,14 +267,12 @@ static int uac_pcm_open(struct snd_pcm_substream *substream)
 	runtime->hw = uac_pcm_hardware;
 
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
-		spin_lock_init(&uac->p_prm.lock);
 		runtime->hw.rate_min = p_srate;
 		runtime->hw.formats = uac_ssize_to_fmt(p_ssize);
 		runtime->hw.channels_min = num_channels(p_chmask);
 		runtime->hw.period_bytes_min = 2 * uac->p_prm.max_psize
 						/ runtime->hw.periods_min;
 	} else {
-		spin_lock_init(&uac->c_prm.lock);
 		runtime->hw.rate_min = c_srate;
 		runtime->hw.formats = uac_ssize_to_fmt(c_ssize);
 		runtime->hw.channels_min = num_channels(c_chmask);
-- 
2.29.2

Re: [PATCH v2 5/5] usb: gadget: u_audio: clean up locking

[Felipe Balbi]

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Jerome Brunet <jbrunet@baylibre.com> writes:

> snd_pcm_stream_lock() is held when the ALSA .trigger() callback is called.
> The lock of 'struct uac_rtd_params' is not necessary since all its locking
> operation are done under the snd_pcm_stream_lock() too.
>
> Also, usb_request .complete() is called with irqs disabled, so saving and
> restoring the irqs is not necessary.
>
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

This is nice!

Acked-by: Felipe Balbi <balbi@.kernel.org>

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balbi

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