Messages in this thread | | | Date | Tue, 25 Feb 2020 18:40:41 +0530 | From | Amol Grover <> | Subject | Re: [PATCH 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro |
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On Mon, Feb 24, 2020 at 01:18:01PM -0800, David Miller wrote: > From: Amol Grover <frextrite@gmail.com> > Date: Sat, 22 Feb 2020 12:08:36 +0530 > > > ipmr_for_each_table() uses list_for_each_entry_rcu() for > > traversing outside of an RCU read-side critical section but > > under the protection of pernet_ops_rwsem. Hence add the > > corresponding lockdep expression to silence the following > > false-positive warning at boot: > > > > [ 0.645292] ============================= > > [ 0.645294] WARNING: suspicious RCU usage > > [ 0.645296] 5.5.4-stable #17 Not tainted > > [ 0.645297] ----------------------------- > > [ 0.645299] net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!! > > > > Signed-off-by: Amol Grover <frextrite@gmail.com> > > This patch series causes build problems, please fix and resubmit the entire > series: > > [davem@localhost net-next]$ make net/ipv4/ipmr.o > CALL scripts/checksyscalls.sh > CALL scripts/atomic/check-atomics.sh > DESCEND objtool > CC net/ipv4/ipmr.o > In file included from ./include/linux/rculist.h:11, > from ./include/linux/pid.h:5, > from ./include/linux/sched.h:14, > from ./include/linux/uaccess.h:5, > from net/ipv4/ipmr.c:24: > net/ipv4/ipmr.c: In function ‘ipmr_get_table’: > ./include/linux/rculist.h:63:25: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] > RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(), \ > ./include/linux/rcupdate.h:263:52: note: in definition of macro ‘RCU_LOCKDEP_WARN’ > if (debug_lockdep_rcu_enabled() && !__warned && (c)) { \ > ^ > ./include/linux/rculist.h:381:7: note: in expansion of macro ‘__list_check_rcu’ > for (__list_check_rcu(dummy, ## cond, 0), \ > ^~~~~~~~~~~~~~~~ > net/ipv4/ipmr.c:113:2: note: in expansion of macro ‘list_for_each_entry_rcu’ > list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \ > ^~~~~~~~~~~~~~~~~~~~~~~ > net/ipv4/ipmr.c:138:2: note: in expansion of macro ‘ipmr_for_each_table’ > ipmr_for_each_table(mrt, net) { > ^~~~~~~~~~~~~~~~~~~
This is a build warning due to incorrect operator precedence in __list_check_rcu macro. This has already been reported and the patch submitted [1]. Infact the patch is currently queued for v5.7.
[1] https://lore.kernel.org/patchwork/patch/1181886/
Thanks Amol
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