arch/um/drivers/vector_kern.c:471 destroy_queue() warn: variable dereferenced before check 'qi' (see line 468)

[Dan Carpenter]

[ Obviously, the commit just did COMPILE_TEST or something.  Anyway... -dan ]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   7c6c4ed80b874f721bc7c2c937e098c56e37d2f0
commit: b555cb66583e99158cfef8e91c025252cefae55b um: vector: Eliminate the dependency on uml_net
config: um-randconfig-r072-20260411 (https://download.01.org/0day-ci/archive/20260411/202604110937.MLUL70Lx-lkp@xxxxxxxxx/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project ae825cb8cea7f3ac8e5e4096f22713845cf5e501)
smatch: v0.5.0-9004-gb810ac53

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: b555cb66583e ("um: vector: Eliminate the dependency on uml_net")
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Dan Carpenter <error27@xxxxxxxxx>
| Closes: https://lore.kernel.org/r/202604110937.MLUL70Lx-lkp@xxxxxxxxx/

smatch warnings:
arch/um/drivers/vector_kern.c:471 destroy_queue() warn: variable dereferenced before check 'qi' (see line 468)

vim +/qi +471 arch/um/drivers/vector_kern.c

49da7e64f33e80 Anton Ivanov 2017-11-20  464  static void destroy_queue(struct vector_queue *qi)
49da7e64f33e80 Anton Ivanov 2017-11-20  465  {
49da7e64f33e80 Anton Ivanov 2017-11-20  466  	int i;
49da7e64f33e80 Anton Ivanov 2017-11-20  467  	struct iovec *iov;
49da7e64f33e80 Anton Ivanov 2017-11-20 @468  	struct vector_private *vp = netdev_priv(qi->dev);
                                                                                        ^^^^^^^
Dereference

49da7e64f33e80 Anton Ivanov 2017-11-20  469  	struct mmsghdr *mmsg_vector;
49da7e64f33e80 Anton Ivanov 2017-11-20  470  
49da7e64f33e80 Anton Ivanov 2017-11-20 @471  	if (qi == NULL)
                                                    ^^^^^^^^^^
Checked too late.

49da7e64f33e80 Anton Ivanov 2017-11-20  472  		return;
49da7e64f33e80 Anton Ivanov 2017-11-20  473  	/* deallocate any skbuffs - we rely on any unused to be
49da7e64f33e80 Anton Ivanov 2017-11-20  474  	 * set to NULL.
49da7e64f33e80 Anton Ivanov 2017-11-20  475  	 */

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