fs/netfs/objects.c:148:5-24: WARNING: atomic_dec_and_test variation before object free at line 150.

From: kernel test robot
Date: Sun Sep 08 2024 - 11:25:34 EST


tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: d1f2d51b711a3b7f1ae1b46701c769c1d580fa7f
commit: f89ea63f1c65d3e93b255f14f9d9e05df87955fa netfs, 9p: Fix race between umount and async request completion
date: 3 months ago
config: x86_64-randconfig-102-20240908 (https://download.01.org/0day-ci/archive/20240908/202409082345.wiwtJarb-lkp@xxxxxxxxx/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

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
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409082345.wiwtJarb-lkp@xxxxxxxxx/

cocci warnings: (new ones prefixed by >>)
>> fs/netfs/objects.c:148:5-24: WARNING: atomic_dec_and_test variation before object free at line 150.

vim +148 fs/netfs/objects.c

123
124 static void netfs_free_request(struct work_struct *work)
125 {
126 struct netfs_io_request *rreq =
127 container_of(work, struct netfs_io_request, work);
128 struct netfs_inode *ictx = netfs_inode(rreq->inode);
129 unsigned int i;
130
131 trace_netfs_rreq(rreq, netfs_rreq_trace_free);
132 netfs_proc_del_rreq(rreq);
133 netfs_clear_subrequests(rreq, false);
134 if (rreq->netfs_ops->free_request)
135 rreq->netfs_ops->free_request(rreq);
136 if (rreq->cache_resources.ops)
137 rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
138 if (rreq->direct_bv) {
139 for (i = 0; i < rreq->direct_bv_count; i++) {
140 if (rreq->direct_bv[i].bv_page) {
141 if (rreq->direct_bv_unpin)
142 unpin_user_page(rreq->direct_bv[i].bv_page);
143 }
144 }
145 kvfree(rreq->direct_bv);
146 }
147
> 148 if (atomic_dec_and_test(&ictx->io_count))
149 wake_up_var(&ictx->io_count);
> 150 call_rcu(&rreq->rcu, netfs_free_request_rcu);
151 }
152

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