linux-kernel - [PATCH 3.2 139/147] [media] rc: Fix input deadlock and transmit error in redrat3 driver

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Date:   Mon, 06 Nov 2017 23:03:07 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Andrew Vincer" <Andrew.Vincer@...rat.co.uk>,
        "Andrew Vincer" <andrew@...rat.co.uk>,
        "Jarod Wilson" <jarod@...hat.com>,
        "Mauro Carvalho Chehab" <mchehab@...hat.com>
Subject: [PATCH 3.2 139/147] [media] rc: Fix input deadlock and transmit
 error in redrat3 driver

3.2.95-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Vincer <Andrew.Vincer@...rat.co.uk>

commit dbea1880368071dfa97d5e6aa4a368e7d0146a85 upstream.

Fixed submit urb logic so hardware doesn't hang trying to transmit
signal data

Removed unneeded enable/disable detector commands in
redrat3_transmit_ir (the hardware does this anyway) and converted
arguments to unsigned as per 5588dc2

Signed-off-by: Andrew Vincer <andrew@...rat.co.uk>
Cc: Jarod Wilson <jarod@...hat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/rc/redrat3.c | 52 ++++++++++++++++------------------------------
 1 file changed, 18 insertions(+), 34 deletions(-)

--- a/drivers/media/rc/redrat3.c
+++ b/drivers/media/rc/redrat3.c
@@ -286,12 +286,6 @@ static void redrat3_issue_async(struct r
 
 	rr3_ftr(rr3->dev, "Entering %s\n", __func__);
 
-	if (!rr3->det_enabled) {
-		dev_warn(rr3->dev, "not issuing async read, "
-			 "detector not enabled\n");
-		return;
-	}
-
 	memset(rr3->bulk_in_buf, 0, rr3->ep_in->wMaxPacketSize);
 	res = usb_submit_urb(rr3->read_urb, GFP_ATOMIC);
 	if (res)
@@ -827,6 +821,7 @@ out:
 static void redrat3_handle_async(struct urb *urb, struct pt_regs *regs)
 {
 	struct redrat3_dev *rr3;
+	int ret;
 
 	if (!urb)
 		return;
@@ -840,15 +835,13 @@ static void redrat3_handle_async(struct
 
 	rr3_ftr(rr3->dev, "Entering %s\n", __func__);
 
-	if (!rr3->det_enabled) {
-		rr3_dbg(rr3->dev, "received a read callback but detector "
-			"disabled - ignoring\n");
-		return;
-	}
-
 	switch (urb->status) {
 	case 0:
-		redrat3_get_ir_data(rr3, urb->actual_length);
+		ret = redrat3_get_ir_data(rr3, urb->actual_length);
+		if (!ret) {
+			/* no error, prepare to read more */
+			redrat3_issue_async(rr3);
+		}
 		break;
 
 	case -ECONNRESET:
@@ -865,11 +858,6 @@ static void redrat3_handle_async(struct
 		rr3->pkttype = 0;
 		break;
 	}
-
-	if (!rr3->transmitting)
-		redrat3_issue_async(rr3);
-	else
-		rr3_dbg(rr3->dev, "IR transmit in progress\n");
 }
 
 static void redrat3_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
@@ -896,21 +884,24 @@ static u16 mod_freq_to_val(unsigned int
 	return (u16)(65536 - (mult / mod_freq));
 }
 
-static int redrat3_set_tx_carrier(struct rc_dev *dev, u32 carrier)
+static int redrat3_set_tx_carrier(struct rc_dev *rcdev, u32 carrier)
 {
-	struct redrat3_dev *rr3 = dev->priv;
+	struct redrat3_dev *rr3 = rcdev->priv;
+	struct device *dev = rr3->dev;
 
+	rr3_dbg(dev, "Setting modulation frequency to %u", carrier);
 	rr3->carrier = carrier;
 
 	return carrier;
 }
 
-static int redrat3_transmit_ir(struct rc_dev *rcdev, int *txbuf, u32 n)
+static int redrat3_transmit_ir(struct rc_dev *rcdev, unsigned *txbuf,
+				unsigned count)
 {
 	struct redrat3_dev *rr3 = rcdev->priv;
 	struct device *dev = rr3->dev;
 	struct redrat3_signal_header header;
-	int i, j, count, ret, ret_len, offset;
+	int i, j, ret, ret_len, offset;
 	int lencheck, cur_sample_len, pipe;
 	char *buffer = NULL, *sigdata = NULL;
 	int *sample_lens = NULL;
@@ -928,20 +919,13 @@ static int redrat3_transmit_ir(struct rc
 		return -EAGAIN;
 	}
 
-	count = n / sizeof(int);
 	if (count > (RR3_DRIVER_MAXLENS * 2))
 		return -EINVAL;
 
+	/* rr3 will disable rc detector on transmit */
+	rr3->det_enabled = false;
 	rr3->transmitting = true;
 
-	redrat3_disable_detector(rr3);
-
-	if (rr3->det_enabled) {
-		dev_err(dev, "%s: cannot tx while rx is enabled\n", __func__);
-		ret = -EIO;
-		goto out;
-	}
-
 	sample_lens = kzalloc(sizeof(int) * RR3_DRIVER_MAXLENS, GFP_KERNEL);
 	if (!sample_lens) {
 		ret = -ENOMEM;
@@ -1055,7 +1039,7 @@ static int redrat3_transmit_ir(struct rc
 	if (ret < 0)
 		dev_err(dev, "Error: control msg send failed, rc %d\n", ret);
 	else
-		ret = n;
+		ret = count;
 
 out:
 	kfree(sample_lens);
@@ -1063,8 +1047,8 @@ out:
 	kfree(sigdata);
 
 	rr3->transmitting = false;
-
-	redrat3_enable_detector(rr3);
+	/* rr3 re-enables rc detector because it was enabled before */
+	rr3->det_enabled = true;
 
 	return ret;
 }