net: can: peak_usb: Do not do dma on the stack

smatch reports the following warnings:
drivers/net/can/usb/peak_usb/pcan_usb_pro.c:514 pcan_usb_pro_drv_loaded() error: doing dma on the stack (buffer)
drivers/net/can/usb/peak_usb/pcan_usb_pro.c:878 pcan_usb_pro_init() error: doing dma on the stack (&fi)
drivers/net/can/usb/peak_usb/pcan_usb_pro.c:889 pcan_usb_pro_init() error: doing dma on the stack (&bi)

See "Documentation/DMA-API-HOWTO.txt" section "What memory is DMA'able?"

Cc: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

2 files changed, 41 insertions, 21 deletions

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c
index 30d79bfa5b10..8ee9d1556e6e 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c
@@ -504,15 +504,24 @@ static int pcan_usb_pro_restart_async(struct peak_usb_device *dev,
         return usb_submit_urb(urb, GFP_ATOMIC);
 }
 
-static void pcan_usb_pro_drv_loaded(struct peak_usb_device *dev, int loaded)
+static int pcan_usb_pro_drv_loaded(struct peak_usb_device *dev, int loaded)
 {
-        u8 buffer[16];
+        u8 *buffer;
+        int err;
+
+        buffer = kmalloc(PCAN_USBPRO_FCT_DRVLD_REQ_LEN, GFP_KERNEL);
+        if (!buffer)
+                return -ENOMEM;
 
         buffer[0] = 0;
         buffer[1] = !!loaded;
 
-        pcan_usb_pro_send_req(dev, PCAN_USBPRO_REQ_FCT,
-                              PCAN_USBPRO_FCT_DRVLD, buffer, sizeof(buffer));
+        err = pcan_usb_pro_send_req(dev, PCAN_USBPRO_REQ_FCT,
+                                    PCAN_USBPRO_FCT_DRVLD, buffer,
+                                    PCAN_USBPRO_FCT_DRVLD_REQ_LEN);
+        kfree(buffer);
+
+        return err;
 }
 
 static inline
@@ -851,21 +860,24 @@ static int pcan_usb_pro_stop(struct peak_usb_device *dev)
  */
 static int pcan_usb_pro_init(struct peak_usb_device *dev)
 {
-        struct pcan_usb_pro_interface *usb_if;
         struct pcan_usb_pro_device *pdev =
                         container_of(dev, struct pcan_usb_pro_device, dev);
+        struct pcan_usb_pro_interface *usb_if = NULL;
+        struct pcan_usb_pro_fwinfo *fi = NULL;
+        struct pcan_usb_pro_blinfo *bi = NULL;
+        int err;
 
         /* do this for 1st channel only */
         if (!dev->prev_siblings) {
-                struct pcan_usb_pro_fwinfo fi;
-                struct pcan_usb_pro_blinfo bi;
-                int err;
-
                 /* allocate netdevices common structure attached to first one */
                 usb_if = kzalloc(sizeof(struct pcan_usb_pro_interface),
                                  GFP_KERNEL);
-                if (!usb_if)
-                        return -ENOMEM;
+                fi = kmalloc(sizeof(struct pcan_usb_pro_fwinfo), GFP_KERNEL);
+                bi = kmalloc(sizeof(struct pcan_usb_pro_blinfo), GFP_KERNEL);
+                if (!usb_if || !fi || !bi) {
+                        err = -ENOMEM;
+                        goto err_out;
+                }
 
                 /* number of ts msgs to ignore before taking one into account */
                 usb_if->cm_ignore_count = 5;
@@ -877,34 +889,34 @@ static int pcan_usb_pro_init(struct peak_usb_device *dev)
                  */
                 err = pcan_usb_pro_send_req(dev, PCAN_USBPRO_REQ_INFO,
                                             PCAN_USBPRO_INFO_FW,
-                                            &fi, sizeof(fi));
+                                            fi, sizeof(*fi));
                 if (err) {
-                        kfree(usb_if);
                         dev_err(dev->netdev->dev.parent,
                                 "unable to read %s firmware info (err %d)\n",
                                 pcan_usb_pro.name, err);
-                        return err;
+                        goto err_out;
                 }
 
                 err = pcan_usb_pro_send_req(dev, PCAN_USBPRO_REQ_INFO,
                                             PCAN_USBPRO_INFO_BL,
-                                            &bi, sizeof(bi));
+                                            bi, sizeof(*bi));
                 if (err) {
-                        kfree(usb_if);
                         dev_err(dev->netdev->dev.parent,
                                 "unable to read %s bootloader info (err %d)\n",
                                 pcan_usb_pro.name, err);
-                        return err;
+                        goto err_out;
                 }
 
+                /* tell the device the can driver is running */
+                err = pcan_usb_pro_drv_loaded(dev, 1);
+                if (err)
+                        goto err_out;
+
                 dev_info(dev->netdev->dev.parent,
                      "PEAK-System %s hwrev %u serial %08X.%08X (%u channels)\n",
                      pcan_usb_pro.name,
-                     bi.hw_rev, bi.serial_num_hi, bi.serial_num_lo,
+                     bi->hw_rev, bi->serial_num_hi, bi->serial_num_lo,
                      pcan_usb_pro.ctrl_count);
-
-                /* tell the device the can driver is running */
-                pcan_usb_pro_drv_loaded(dev, 1);
         } else {
                 usb_if = pcan_usb_pro_dev_if(dev->prev_siblings);
         }
@@ -916,6 +928,13 @@ static int pcan_usb_pro_init(struct peak_usb_device *dev)
         pcan_usb_pro_set_led(dev, 0, 1);
 
         return 0;
+
+ err_out:
+        kfree(bi);
+        kfree(fi);
+        kfree(usb_if);
+
+        return err;
 }
 
 static void pcan_usb_pro_exit(struct peak_usb_device *dev)
diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_pro.h b/drivers/net/can/usb/peak_usb/pcan_usb_pro.h
index a869918c5620..32275af547e0 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_pro.h
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_pro.h
@@ -29,6 +29,7 @@
 
 /* Vendor Request value for XXX_FCT */
 #define PCAN_USBPRO_FCT_DRVLD           5 /* tell device driver is loaded */
+#define PCAN_USBPRO_FCT_DRVLD_REQ_LEN   16
 
 /* PCAN_USBPRO_INFO_BL vendor request record type */
 struct __packed pcan_usb_pro_blinfo {