[media] vp702x: use preallocated buffer in vp702x_usb_inout_cmd

If we need a bigger buffer, we reallocte a new buffer and free the old
one.

Note: This change is tested to compile only as I don't have the
hardware.

Signed-off-by: Florian Mickler <florian@mickler.org>
Cc: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/drivers/media/dvb/dvb-usb/vp702x.c b/drivers/media/dvb/dvb-usb/vp702x.c
index 6dd50bc8418e..54355f84a98f 100644
--- a/drivers/media/dvb/dvb-usb/vp702x.c
+++ b/drivers/media/dvb/dvb-usb/vp702x.c
@@ -116,13 +116,28 @@ int vp702x_usb_inout_op(struct dvb_usb_device *d, u8 *o, int olen, u8 *i, int il
 static int vp702x_usb_inout_cmd(struct dvb_usb_device *d, u8 cmd, u8 *o,
                                 int olen, u8 *i, int ilen, int msec)
 {
+        struct vp702x_device_state *st = d->priv;
         int ret = 0;
         u8 *buf;
         int buflen = max(olen + 2, ilen + 1);
 
-        buf = kmalloc(buflen, GFP_KERNEL);
-        if (!buf)
-                return -ENOMEM;
+        ret = mutex_lock_interruptible(&st->buf_mutex);
+        if (ret < 0)
+                return ret;
+
+        if (buflen > st->buf_len) {
+                buf = kmalloc(buflen, GFP_KERNEL);
+                if (!buf) {
+                        mutex_unlock(&st->buf_mutex);
+                        return -ENOMEM;
+                }
+                info("successfully reallocated a bigger buffer");
+                kfree(st->buf);
+                st->buf = buf;
+                st->buf_len = buflen;
+        } else {
+                buf = st->buf;
+        }
 
         buf[0] = 0x00;
         buf[1] = cmd;
@@ -132,8 +147,8 @@ static int vp702x_usb_inout_cmd(struct dvb_usb_device *d, u8 cmd, u8 *o,
 
         if (ret == 0)
                 memcpy(i, &buf[1], ilen);
+        mutex_unlock(&st->buf_mutex);
 
-        kfree(buf);
         return ret;
 }