ipc/util.c:778:9: sparse: sparse: context imbalance in 'sysvipc_find_ipc' - wrong count at exit

ipc/util.c:778:9: sparse: sparse: context imbalance in 'sysvipc_find_ipc' - wrong count at exit

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: Manfred Spraul <manfred@colorfullife.com>
CC: 0day robot <lkp@intel.com>

Hi Manfred,

First bad commit (maybe != root cause):

tree:   https://github.com/0day-ci/linux/commits/UPDATE-20210821-034214/Rafael-Aquini/ipc-replace-costly-bailout-check-in-sysvipc_find_ipc/20210810-043723
head:   a7e49d3717b678a71049996d24ccecfc3cdb0aa1
commit: a7e49d3717b678a71049996d24ccecfc3cdb0aa1 ipc: replace costly bailout check in sysvipc_find_ipc()
date:   25 hours ago
:::::: branch date: 25 hours ago
:::::: commit date: 25 hours ago
config: x86_64-rhel-8.3-kselftests (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-348-gf0e6938b-dirty
        # https://github.com/0day-ci/linux/commit/a7e49d3717b678a71049996d24ccecfc3cdb0aa1
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review UPDATE-20210821-034214/Rafael-Aquini/ipc-replace-costly-bailout-check-in-sysvipc_find_ipc/20210810-043723
        git checkout a7e49d3717b678a71049996d24ccecfc3cdb0aa1
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)
   ipc/util.c:171:29: sparse: sparse: context imbalance in 'ipc_findkey' - wrong count at exit
   ipc/util.c:277:5: sparse: sparse: context imbalance in 'ipc_addid' - different lock contexts for basic block
   ipc/util.c:431:27: sparse: sparse: context imbalance in 'ipcget_public' - unexpected unlock
>> ipc/util.c:778:9: sparse: sparse: context imbalance in 'sysvipc_find_ipc' - wrong count at exit
   ipc/util.c:789:27: sparse: sparse: context imbalance in 'sysvipc_proc_next' - unexpected unlock
   ipc/util.c:833:27: sparse: sparse: context imbalance in 'sysvipc_proc_stop' - unexpected unlock

vim +/sysvipc_find_ipc +778 ipc/util.c

03f1fc09180b34 Eric W. Biederman 2018-03-23  750  
7ca7e564e049d8 Nadia Derbey      2007-10-18  751  /*
a7e49d3717b678 Manfred Spraul    2021-08-20  752   * This routine locks the ipc structure found at least at index pos.
7ca7e564e049d8 Nadia Derbey      2007-10-18  753   */
b524b9adb3f655 Adrian Bunk       2008-02-06  754  static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
7ca7e564e049d8 Nadia Derbey      2007-10-18  755  					      loff_t *new_pos)
ae7817745eef3b Mike Waychison    2005-09-06  756  {
a7e49d3717b678 Manfred Spraul    2021-08-20  757  	int tmpidx;
7ca7e564e049d8 Nadia Derbey      2007-10-18  758  	struct kern_ipc_perm *ipc;
73ea41302bab5e Kirill Korotaev   2006-10-02  759  
a7e49d3717b678 Manfred Spraul    2021-08-20  760  	tmpidx = pos;
ae7817745eef3b Mike Waychison    2005-09-06  761  
a7e49d3717b678 Manfred Spraul    2021-08-20  762  	ipc = idr_get_next(&ids->ipcs_idr, &tmpidx);
7ca7e564e049d8 Nadia Derbey      2007-10-18  763  	if (ipc != NULL) {
32a27500109812 Davidlohr Bueso   2013-09-11  764  		rcu_read_lock();
32a27500109812 Davidlohr Bueso   2013-09-11  765  		ipc_lock_object(ipc);
a7e49d3717b678 Manfred Spraul    2021-08-20  766  		/*
a7e49d3717b678 Manfred Spraul    2021-08-20  767  		 * We found the object with the index tmpidx.
a7e49d3717b678 Manfred Spraul    2021-08-20  768  		 * For next search, start with tmpidx+1
a7e49d3717b678 Manfred Spraul    2021-08-20  769  		 */
a7e49d3717b678 Manfred Spraul    2021-08-20  770  		*new_pos = tmpidx + 1;
a7e49d3717b678 Manfred Spraul    2021-08-20  771  	} else {
a7e49d3717b678 Manfred Spraul    2021-08-20  772  		/*
a7e49d3717b678 Manfred Spraul    2021-08-20  773  		 * EOF. seq_file can't notice that, thus
a7e49d3717b678 Manfred Spraul    2021-08-20  774  		 * move the offset by one.
a7e49d3717b678 Manfred Spraul    2021-08-20  775  		 */
5e698222c70257 Vasily Averin     2020-05-13  776  		*new_pos = pos + 1;
a7e49d3717b678 Manfred Spraul    2021-08-20  777  	}
5e698222c70257 Vasily Averin     2020-05-13 @778  	return ipc;
ae7817745eef3b Mike Waychison    2005-09-06  779  }
ae7817745eef3b Mike Waychison    2005-09-06  780  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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