[kbuild] Re: [PATCH for-next] RDMA/rxe: rxe_get_av always receives ahp hence no put is needed

[Dan Carpenter <dan.carpenter@oracle.com>]

Hi Md,

https://git-scm.com/docs/git-format-patch#_base_tree_information  ]

url:    https://github.com/intel-lab-lkp/linux/commits/Md-Haris-Iqbal/RDMA-rxe-rxe_get_av-always-receives-ahp-hence-no-put-is-needed/20221020-231859  
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git   for-next
patch link:    https://lore.kernel.org/r/20221020151345.412731-1-haris.phnx%40gmail.com  
patch subject: [PATCH for-next] RDMA/rxe: rxe_get_av always receives ahp hence no put is needed
config: openrisc-randconfig-m041-20221024
compiler: or1k-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/infiniband/sw/rxe/rxe_av.c:133 rxe_get_av() error: we previously assumed 'ahp' could be null (see line 107)

vim +/ahp +133 drivers/infiniband/sw/rxe/rxe_av.c

63221acb0c6314 Bob Pearson 2022-03-03  102  struct rxe_av *rxe_get_av(struct rxe_pkt_info *pkt, struct rxe_ah **ahp)
8700e3e7c4857d Moni Shoua  2016-06-16  103  {
e2fe06c9080694 Bob Pearson 2021-10-07  104  	struct rxe_ah *ah;
e2fe06c9080694 Bob Pearson 2021-10-07  105  	u32 ah_num;
e2fe06c9080694 Bob Pearson 2021-10-07  106  
63221acb0c6314 Bob Pearson 2022-03-03 @107  	if (ahp)
                                                    ^^^
Check for NULL.  Maybe this check can be deleted.  It's never NULL in
the current code.

63221acb0c6314 Bob Pearson 2022-03-03  108  		*ahp = NULL;
63221acb0c6314 Bob Pearson 2022-03-03  109  
8700e3e7c4857d Moni Shoua  2016-06-16  110  	if (!pkt || !pkt->qp)
8700e3e7c4857d Moni Shoua  2016-06-16  111  		return NULL;
8700e3e7c4857d Moni Shoua  2016-06-16  112  
8700e3e7c4857d Moni Shoua  2016-06-16  113  	if (qp_type(pkt->qp) == IB_QPT_RC || qp_type(pkt->qp) == IB_QPT_UC)
8700e3e7c4857d Moni Shoua  2016-06-16  114  		return &pkt->qp->pri_av;
8700e3e7c4857d Moni Shoua  2016-06-16  115  
e2fe06c9080694 Bob Pearson 2021-10-07  116  	if (!pkt->wqe)
e2fe06c9080694 Bob Pearson 2021-10-07  117  		return NULL;
e2fe06c9080694 Bob Pearson 2021-10-07  118  
e2fe06c9080694 Bob Pearson 2021-10-07  119  	ah_num = pkt->wqe->wr.wr.ud.ah_num;
e2fe06c9080694 Bob Pearson 2021-10-07  120  	if (ah_num) {
                                                    ^^^^^^
Perhaps it is a false positive if checking "ah_num" is intended to be
equivalent to checking "ahp"?

e2fe06c9080694 Bob Pearson 2021-10-07  121  		/* only new user provider or kernel client */
e2fe06c9080694 Bob Pearson 2021-10-07  122  		ah = rxe_pool_get_index(&pkt->rxe->ah_pool, ah_num);
63221acb0c6314 Bob Pearson 2022-03-03  123  		if (!ah) {
e2fe06c9080694 Bob Pearson 2021-10-07  124  			pr_warn("Unable to find AH matching ah_num\n");
e2fe06c9080694 Bob Pearson 2021-10-07  125  			return NULL;
e2fe06c9080694 Bob Pearson 2021-10-07  126  		}
63221acb0c6314 Bob Pearson 2022-03-03  127  
63221acb0c6314 Bob Pearson 2022-03-03  128  		if (rxe_ah_pd(ah) != pkt->qp->pd) {
63221acb0c6314 Bob Pearson 2022-03-03  129  			pr_warn("PDs don't match for AH and QP\n");
3197706abd0532 Bob Pearson 2022-03-03  130  			rxe_put(ah);
63221acb0c6314 Bob Pearson 2022-03-03  131  			return NULL;
63221acb0c6314 Bob Pearson 2022-03-03  132  		}
63221acb0c6314 Bob Pearson 2022-03-03 @133  		*ahp = ah;
                                                        ^^^^
Unchecked dereference.

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