[kbuild] drivers/most/core.c:1287 most_register_interface() error: we previously assumed 'iface' could be null (see line 1285)

[Dan Carpenter]

Hi Christian,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162
commit: b276527539188f1f61c082ebef27803db93e536d staging: most: move core files out of the staging area
date:   10 weeks ago

config: mips-randconfig-m031-20200601 (attached as .config)
compiler: mipsel-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

smatch warnings:
drivers/most/core.c:1287 most_register_interface() error: we previously assumed 'iface' could be null (see line 1285)

# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b276527539188f1f61c082ebef27803db93e536d
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git remote update linus
git checkout b276527539188f1f61c082ebef27803db93e536d
vim +/iface +1287 drivers/most/core.c

4d5f022f3a664e drivers/staging/most/core.c          Christian Gromm     2017-11-21  1279  int most_register_interface(struct most_interface *iface)
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1280  {
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1281  	unsigned int i;
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1282  	int id;
fcb7fad82e23f6 drivers/staging/most/core.c          Christian Gromm     2017-11-21  1283  	struct most_channel *c;
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1284  
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24 @1285  	if (!iface || !iface->enqueue || !iface->configure ||
                                                                                                    ^^^^^^
Check for NULL.

57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1286  	    !iface->poison_channel || (iface->num_channels > MAX_CHANNELS)) {
6a82c775812944 drivers/staging/most/core.c          Christian Gromm     2020-01-23 @1287  		dev_err(iface->dev, "Bad interface or channel overflow\n");
                                                                                                                ^^^^^^^^^^
Dereference.  "iface" can't be NULL.  Just delete the check.

4d5f022f3a664e drivers/staging/most/core.c          Christian Gromm     2017-11-21  1288  		return -EINVAL;
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1289  	}
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1290  
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1291  	id = ida_simple_get(&mdev_id, 0, 0, GFP_KERNEL);
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1292  	if (id < 0) {
b7935e52dd9869 drivers/staging/most/core.c          Christian Gromm     2020-01-23  1293  		dev_err(iface->dev, "Failed to allocate device ID\n");
4d5f022f3a664e drivers/staging/most/core.c          Christian Gromm     2017-11-21  1294  		return id;
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1295  	}
57562a72414ca3 drivers/staging/most/mostcore/core.c Christian Gromm     2015-07-24  1296  

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