Re: [PATCH 8/8] usb_pcwd: remove superfluous usb_device pointer
From: Dan Carpenter
Date: Sat May 13 2023 - 04:52:45 EST
Hi Oliver,
kernel test robot noticed the following build warnings:
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Oliver-Neukum/pcwd_usb-stop-open-race-disconnect/20230427-223413
base: linus/master
patch link: https://lore.kernel.org/r/20230427133350.31064-9-oneukum%40suse.com
patch subject: [PATCH 8/8] usb_pcwd: remove superfluous usb_device pointer
config: parisc-randconfig-m041-20230509 (https://download.01.org/0day-ci/archive/20230512/202305122231.n8RlGMhT-lkp@xxxxxxxxx/config)
compiler: hppa-linux-gcc (GCC) 12.1.0
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Dan Carpenter <error27@xxxxxxxxx>
| Link: https://lore.kernel.org/r/202305122231.n8RlGMhT-lkp@xxxxxxxxx/
smatch warnings:
drivers/watchdog/pcwd_usb.c:215 usb_pcwd_send_command() warn: variable dereferenced before check 'usb_pcwd' (see line 211)
vim +/usb_pcwd +215 drivers/watchdog/pcwd_usb.c
143a2e54bf5321 drivers/watchdog/pcwd_usb.c Wim Van Sebroeck 2009-03-18 206 static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd,
143a2e54bf5321 drivers/watchdog/pcwd_usb.c Wim Van Sebroeck 2009-03-18 207 unsigned char cmd, unsigned char *msb, unsigned char *lsb)
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 208 {
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 209 int got_response, count;
5412df0bda90a2 drivers/watchdog/pcwd_usb.c Guenter Roeck 2013-10-14 210 unsigned char *buf;
41b4f0869562d7 drivers/watchdog/pcwd_usb.c Oliver Neukum 2023-04-27 @211 struct usb_device *udev = interface_to_usbdev(usb_pcwd->interface);
^^^^^^^^^^
Dereference.
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 212
143a2e54bf5321 drivers/watchdog/pcwd_usb.c Wim Van Sebroeck 2009-03-18 213 /* We will not send any commands if the USB PCWD device does
143a2e54bf5321 drivers/watchdog/pcwd_usb.c Wim Van Sebroeck 2009-03-18 214 * not exist */
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 @215 if ((!usb_pcwd) || (!usb_pcwd->exists))
^^^^^^^^^^^
Checked too late.
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 216 return -1;
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 217
5412df0bda90a2 drivers/watchdog/pcwd_usb.c Guenter Roeck 2013-10-14 218 buf = kmalloc(6, GFP_KERNEL);
5412df0bda90a2 drivers/watchdog/pcwd_usb.c Guenter Roeck 2013-10-14 219 if (buf == NULL)
5412df0bda90a2 drivers/watchdog/pcwd_usb.c Guenter Roeck 2013-10-14 220 return 0;
5412df0bda90a2 drivers/watchdog/pcwd_usb.c Guenter Roeck 2013-10-14 221
143a2e54bf5321 drivers/watchdog/pcwd_usb.c Wim Van Sebroeck 2009-03-18 222 /* The USB PC Watchdog uses a 6 byte report format.
143a2e54bf5321 drivers/watchdog/pcwd_usb.c Wim Van Sebroeck 2009-03-18 223 * The board currently uses only 3 of the six bytes of the report. */
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 224 buf[0] = cmd; /* Byte 0 = CMD */
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 225 buf[1] = *msb; /* Byte 1 = Data MSB */
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 226 buf[2] = *lsb; /* Byte 2 = Data LSB */
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 227 buf[3] = buf[4] = buf[5] = 0; /* All other bytes not used */
^1da177e4c3f41 drivers/char/watchdog/pcwd_usb.c Linus Torvalds 2005-04-16 228
d7e92f7f768477 drivers/watchdog/pcwd_usb.c Greg Kroah-Hartman 2013-12-19 229 dev_dbg(&usb_pcwd->interface->dev,
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