ipmr_for_each_table() macro uses list_for_each_entry_rcu()
for traversing outside of an RCU read side critical section
but under the protection of rtnl_mutex. Hence, add the
corresponding lockdep expression to silence the following
false-positive warning at boot:
[ 4.319347] =============================
[ 4.319349] WARNING: suspicious RCU usage
[ 4.319351] 5.5.4-stable #17 Tainted: G E
[ 4.319352] -----------------------------
[ 4.319354] net/ipv4/ipmr.c:1757 RCU-list traversed in non-reader section!!
Signed-off-by: Amol Grover <[email protected]>
---
net/ipv4/ipmr.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 6e68def66822..99c864eb6e34 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -110,7 +110,8 @@ static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list)
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held())
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1
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 <[email protected]>
---
net/ipv4/ipmr.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 99c864eb6e34..950ffe9943da 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
static void ipmr_expire_process(struct timer_list *t);
#ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
- list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
- lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net) \
+ list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+ lockdep_rtnl_is_held() || \
+ lockdep_is_held(&pernet_ops_rwsem))
static struct mr_table *ipmr_mr_table_iter(struct net *net,
struct mr_table *mrt)
--
2.24.1
From: Amol Grover <[email protected]>
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 <[email protected]>
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) {
^~~~~~~~~~~~~~~~~~~
On Mon, Feb 24, 2020 at 01:18:01PM -0800, David Miller wrote:
> From: Amol Grover <[email protected]>
> 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 <[email protected]>
>
> 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