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Groups > linux.kernel > #1497400

[PATCH 11/26] digitv: don't do DMA on stack

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The USB control messages require DMA to work. We cannot pass
a stack-allocated buffer, as it is not warranted that the
stack would be into a DMA enabled area.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
 drivers/media/usb/dvb-usb/digitv.c | 20 +++++++++++---------
 drivers/media/usb/dvb-usb/digitv.h |  3 +++
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/digitv.c b/drivers/media/usb/dvb-usb/digitv.c
index 63134335c994..09f8c28bd4db 100644
--- a/drivers/media/usb/dvb-usb/digitv.c
+++ b/drivers/media/usb/dvb-usb/digitv.c
@@ -28,20 +28,22 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
 static int digitv_ctrl_msg(struct dvb_usb_device *d,
 		u8 cmd, u8 vv, u8 *wbuf, int wlen, u8 *rbuf, int rlen)
 {
+	struct digitv_state *st = d->priv;
 	int wo = (rbuf == NULL || rlen == 0); /* write-only */
-	u8 sndbuf[7],rcvbuf[7];
-	memset(sndbuf,0,7); memset(rcvbuf,0,7);
 
-	sndbuf[0] = cmd;
-	sndbuf[1] = vv;
-	sndbuf[2] = wo ? wlen : rlen;
+	memset(st->sndbuf, 0, 7);
+	memset(st->rcvbuf, 0, 7);
+
+	st->sndbuf[0] = cmd;
+	st->sndbuf[1] = vv;
+	st->sndbuf[2] = wo ? wlen : rlen;
 
 	if (wo) {
-		memcpy(&sndbuf[3],wbuf,wlen);
-		dvb_usb_generic_write(d,sndbuf,7);
+		memcpy(&st->sndbuf[3], wbuf, wlen);
+		dvb_usb_generic_write(d, st->sndbuf, 7);
 	} else {
-		dvb_usb_generic_rw(d,sndbuf,7,rcvbuf,7,10);
-		memcpy(rbuf,&rcvbuf[3],rlen);
+		dvb_usb_generic_rw(d, st->sndbuf, 7, st->rcvbuf, 7, 10);
+		memcpy(rbuf, &st->rcvbuf[3], rlen);
 	}
 	return 0;
 }
diff --git a/drivers/media/usb/dvb-usb/digitv.h b/drivers/media/usb/dvb-usb/digitv.h
index 908c09f4966b..cf104689bdff 100644
--- a/drivers/media/usb/dvb-usb/digitv.h
+++ b/drivers/media/usb/dvb-usb/digitv.h
@@ -6,6 +6,9 @@
 
 struct digitv_state {
     int is_nxt6000;
+
+    unsigned char sndbuf[7];
+    unsigned char rcvbuf[7];
 };
 
 /* protocol (from usblogging and the SDK:
-- 
2.7.4

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[PATCH 00/26] Don't use stack for DMA transers on dvb-usb drivers Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
  [PATCH 21/26] pctv452e: don't call BUG_ON() on non-fatal error Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
    [PATCH v2 21/26] pctv452e: don't call BUG_ON() on non-fatal error Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-08 12:20 +0200
  [PATCH 26/26] digitv: handle error code on RC query Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
  [PATCH 06/26] cxusb: don't do DMA on stack Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
    Re: [PATCH 06/26] cxusb: don't do DMA on stack Patrick Boettcher <patrick.boettcher@posteo.de> - 2016-10-10 08:40 +0200
  [PATCH 01/26] af9005: don't do DMA on stack Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
  [PATCH 11/26] digitv: don't do DMA on stack Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
    Re: [PATCH 11/26] digitv: don't do DMA on stack Patrick Boettcher <patrick.boettcher@posteo.de> - 2016-10-10 08:40 +0200
  [PATCH 02/26] cinergyT2-core: don't do DMA on stack Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
    Re: [PATCH 02/26] cinergyT2-core: don't do DMA on stack Patrick Boettcher <patrick.boettcher@posteo.de> - 2016-10-10 08:40 +0200
  [PATCH 15/26] dtt200u: handle USB control message errors Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
  [PATCH 14/26] dtt200u: don't do DMA on stack Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
    Re: [PATCH 14/26] dtt200u: don't do DMA on stack Patrick Boettcher <patrick.boettcher@posteo.de> - 2016-10-10 08:40 +0200
  [PATCH 04/26] cinergyT2-fe: cache stats at cinergyt2_fe_read_status() Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
  [PATCH 18/26] gp8psk: don't go past the buffer size Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:30 +0200
  [PATCH 07/26] dib0700: be sure that dib0700_ctrl_rd() users can do DMA Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:40 +0200
    Re: [PATCH 07/26] dib0700: be sure that dib0700_ctrl_rd() users can  do DMA Patrick Boettcher <patrick.boettcher@posteo.de> - 2016-10-10 08:40 +0200
  [PATCH 17/26] gp8psk: don't do DMA on stack Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:40 +0200
  [PATCH 23/26] dvb-usb: warn if return value for USB read/write routines is not checked Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2016-10-07 19:40 +0200

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