ctrl->subsys->namespaces and subsys->namespaces are traversed with
hlist_for_each_entry_rcu outside an RCU read-side critical section
but under the protection of subsys->lock.
Hence, add the corresponding lockdep expression to the list traversal
primitive to silence false-positive lockdep warnings, and
harden RCU lists.
Reviewed-by: Joel Fernandes (Google) <[email protected]>
Signed-off-by: Amol Grover <[email protected]>
---
v2:
- Fix sparse error
CHECK: Alignment should match open parenthesis
- Remove global macro and use local lockdep expressions
drivers/nvme/target/core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 28438b833c1b..c2d6c2dd53fa 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -555,7 +555,8 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
} else {
struct nvmet_ns *old;
- list_for_each_entry_rcu(old, &subsys->namespaces, dev_link) {
+ list_for_each_entry_rcu(old, &subsys->namespaces, dev_link,
+ lockdep_is_held(&subsys->lock)) {
BUG_ON(ns->nsid == old->nsid);
if (ns->nsid < old->nsid)
break;
@@ -1172,7 +1173,8 @@ static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,
ctrl->p2p_client = get_device(req->p2p_client);
- list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link)
+ list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
+ lockdep_is_held(&subsys->lock))
nvmet_p2pmem_ns_add_p2p(ctrl, ns);
}
--
2.24.1
Hi Amol,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on hch-configfs/for-next]
[also build test WARNING on linux/master linus/master v5.5-rc5 next-20200110]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Amol-Grover/drivers-nvme-target-core-Pass-lockdep-expression-to-RCU-lists/20200111-084508
base: git://git.infradead.org/users/hch/configfs.git for-next
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gcc (GCC) 7.5.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.5.0 make.cross ARCH=sh
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All warnings (new ones prefixed by >>):
In file included from include/linux/rbtree.h:22:0,
from include/linux/mm_types.h:10,
from include/linux/mmzone.h:21,
from include/linux/gfp.h:6,
from include/linux/umh.h:4,
from include/linux/kmod.h:9,
from include/linux/module.h:13,
from drivers/nvme/target/core.c:7:
drivers/nvme/target/core.c: In function 'nvmet_setup_p2p_ns_map':
drivers/nvme/target/core.c:1179:22: error: 'subsys' undeclared (first use in this function); did you mean 'to_subsys'?
lockdep_is_held(&subsys->lock))
^
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:371:7: note: in expansion of macro '__list_check_rcu'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~~~~~~~~~~~~~
>> include/linux/rculist.h:371:34: note: in expansion of macro 'lockdep_is_held'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~
drivers/nvme/target/core.c:1178:2: note: in expansion of macro 'list_for_each_entry_rcu'
list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
^~~~~~~~~~~~~~~~~~~~~~~
drivers/nvme/target/core.c:1179:22: note: each undeclared identifier is reported only once for each function it appears in
lockdep_is_held(&subsys->lock))
^
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:371:7: note: in expansion of macro '__list_check_rcu'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~~~~~~~~~~~~~
>> include/linux/rculist.h:371:34: note: in expansion of macro 'lockdep_is_held'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~
drivers/nvme/target/core.c:1178:2: note: in expansion of macro 'list_for_each_entry_rcu'
list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
^~~~~~~~~~~~~~~~~~~~~~~
vim +/lockdep_is_held +371 include/linux/rculist.h
ff3c44e6750545 Tom Herbert 2016-03-07 358
82524746c27fa4 Franck Bui-Huu 2008-05-12 359 /**
82524746c27fa4 Franck Bui-Huu 2008-05-12 360 * list_for_each_entry_rcu - iterate over rcu list of given type
82524746c27fa4 Franck Bui-Huu 2008-05-12 361 * @pos: the type * to use as a loop cursor.
82524746c27fa4 Franck Bui-Huu 2008-05-12 362 * @head: the head for your list.
3943f42c11896c Andrey Utkin 2014-11-14 363 * @member: the name of the list_head within the struct.
28875945ba98d1 Joel Fernandes (Google 2019-07-16 364) * @cond: optional lockdep expression if called from non-RCU protection.
82524746c27fa4 Franck Bui-Huu 2008-05-12 365 *
82524746c27fa4 Franck Bui-Huu 2008-05-12 366 * This list-traversal primitive may safely run concurrently with
82524746c27fa4 Franck Bui-Huu 2008-05-12 367 * the _rcu list-mutation primitives such as list_add_rcu()
82524746c27fa4 Franck Bui-Huu 2008-05-12 368 * as long as the traversal is guarded by rcu_read_lock().
82524746c27fa4 Franck Bui-Huu 2008-05-12 369 */
28875945ba98d1 Joel Fernandes (Google 2019-07-16 370) #define list_for_each_entry_rcu(pos, head, member, cond...) \
28875945ba98d1 Joel Fernandes (Google 2019-07-16 @371) for (__list_check_rcu(dummy, ## cond, 0), \
28875945ba98d1 Joel Fernandes (Google 2019-07-16 372) pos = list_entry_rcu((head)->next, typeof(*pos), member); \
e66eed651fd18a Linus Torvalds 2011-05-19 373 &pos->member != (head); \
72c6a9870f9010 Jiri Pirko 2009-04-14 374 pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
82524746c27fa4 Franck Bui-Huu 2008-05-12 375
:::::: The code at line 371 was first introduced by commit
:::::: 28875945ba98d1b47a8a706812b6494d165bb0a0 rcu: Add support for consolidated-RCU reader checking
:::::: TO: Joel Fernandes (Google) <[email protected]>
:::::: CC: Paul E. McKenney <[email protected]>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation
Hi Amol,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on hch-configfs/for-next]
[also build test ERROR on linux/master linus/master v5.5-rc6 next-20200117]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Amol-Grover/drivers-nvme-target-core-Pass-lockdep-expression-to-RCU-lists/20200111-084508
base: git://git.infradead.org/users/hch/configfs.git for-next
config: i386-randconfig-e001-20200118 (attached as .config)
compiler: gcc-7 (Debian 7.5.0-3) 7.5.0
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All errors (new ones prefixed by >>):
In file included from include/linux/rbtree.h:22:0,
from include/linux/mm_types.h:10,
from include/linux/mmzone.h:21,
from include/linux/gfp.h:6,
from include/linux/umh.h:4,
from include/linux/kmod.h:9,
from include/linux/module.h:13,
from drivers/nvme/target/core.c:7:
drivers/nvme/target/core.c: In function 'nvmet_setup_p2p_ns_map':
>> drivers/nvme/target/core.c:1179:22: error: 'subsys' undeclared (first use in this function); did you mean 'to_subsys'?
lockdep_is_held(&subsys->lock))
^
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:371:7: note: in expansion of macro '__list_check_rcu'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~~~~~~~~~~~~~
include/linux/rculist.h:371:34: note: in expansion of macro 'lockdep_is_held'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~
drivers/nvme/target/core.c:1178:2: note: in expansion of macro 'list_for_each_entry_rcu'
list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
^~~~~~~~~~~~~~~~~~~~~~~
drivers/nvme/target/core.c:1179:22: note: each undeclared identifier is reported only once for each function it appears in
lockdep_is_held(&subsys->lock))
^
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:371:7: note: in expansion of macro '__list_check_rcu'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~~~~~~~~~~~~~
include/linux/rculist.h:371:34: note: in expansion of macro 'lockdep_is_held'
for (__list_check_rcu(dummy, ## cond, 0), \
^~~~
drivers/nvme/target/core.c:1178:2: note: in expansion of macro 'list_for_each_entry_rcu'
list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
^~~~~~~~~~~~~~~~~~~~~~~
vim +1179 drivers/nvme/target/core.c
1164
1165 /*
1166 * Note: ctrl->subsys->lock should be held when calling this function
1167 */
1168 static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,
1169 struct nvmet_req *req)
1170 {
1171 struct nvmet_ns *ns;
1172
1173 if (!req->p2p_client)
1174 return;
1175
1176 ctrl->p2p_client = get_device(req->p2p_client);
1177
1178 list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
> 1179 lockdep_is_held(&subsys->lock))
1180 nvmet_p2pmem_ns_add_p2p(ctrl, ns);
1181 }
1182
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation