2020-02-25 12:43:31

by Madhuparna Bhowmik

Subject: [PATCH] net: core: devlink.c: Use built-in RCU list checking

From: Madhuparna Bhowmik <[email protected]>

list_for_each_entry_rcu() has built-in RCU and lock checking.

Pass cond argument to list_for_each_entry_rcu() to silence
false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled.

The devlink->lock is held when devlink_dpipe_table_find()
is called in non RCU read side section. Therefore, pass struct devlink
to devlink_dpipe_table_find() for lockdep checking.

Signed-off-by: Madhuparna Bhowmik <[email protected]>
---
net/core/devlink.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index e82750bdc496..a92ab58304e5 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -2103,11 +2103,11 @@ static int devlink_dpipe_entry_put(struct sk_buff *skb,

static struct devlink_dpipe_table *
devlink_dpipe_table_find(struct list_head *dpipe_tables,
- const char *table_name)
+ const char *table_name, struct devlink *devlink)
{
struct devlink_dpipe_table *table;
-
- list_for_each_entry_rcu(table, dpipe_tables, list) {
+ list_for_each_entry_rcu(table, dpipe_tables, list,
+ lockdep_is_held(&devlink->lock)) {
if (!strcmp(table->name, table_name))
return table;
}
@@ -2226,7 +2226,7 @@ static int devlink_nl_cmd_dpipe_entries_get(struct sk_buff *skb,

table_name = nla_data(info->attrs[DEVLINK_ATTR_DPIPE_TABLE_NAME]);
table = devlink_dpipe_table_find(&devlink->dpipe_table_list,
- table_name);
+ table_name, devlink);
if (!table)
return -EINVAL;

@@ -2382,7 +2382,7 @@ static int devlink_dpipe_table_counters_set(struct devlink *devlink,
struct devlink_dpipe_table *table;

table = devlink_dpipe_table_find(&devlink->dpipe_table_list,
- table_name);
+ table_name, devlink);
if (!table)
return -EINVAL;

@@ -6814,7 +6814,7 @@ bool devlink_dpipe_table_counter_enabled(struct devlink *devlink,

rcu_read_lock();
table = devlink_dpipe_table_find(&devlink->dpipe_table_list,
- table_name);
+ table_name, devlink);
enabled = false;
if (table)
enabled = table->counters_enabled;
@@ -6845,7 +6845,8 @@ int devlink_dpipe_table_register(struct devlink *devlink,

mutex_lock(&devlink->lock);

- if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name)) {
+ if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name,
+ devlink)) {
err = -EEXIST;
goto unlock;
}
@@ -6881,7 +6882,7 @@ void devlink_dpipe_table_unregister(struct devlink *devlink,

mutex_lock(&devlink->lock);
table = devlink_dpipe_table_find(&devlink->dpipe_table_list,
- table_name);
+ table_name, devlink);
if (!table)
goto unlock;
list_del_rcu(&table->list);
@@ -7038,7 +7039,7 @@ int devlink_dpipe_table_resource_set(struct devlink *devlink,

mutex_lock(&devlink->lock);
table = devlink_dpipe_table_find(&devlink->dpipe_table_list,
- table_name);
+ table_name, devlink);
if (!table) {
err = -EINVAL;
goto out;
--
2.17.1

2020-02-25 13:11:39

by Jiri Pirko

Subject: Re: [PATCH] net: core: devlink.c: Use built-in RCU list checking

Tue, Feb 25, 2020 at 01:27:45PM CET, [email protected] wrote:
>From: Madhuparna Bhowmik <[email protected]>
>
>list_for_each_entry_rcu() has built-in RCU and lock checking.
>
>Pass cond argument to list_for_each_entry_rcu() to silence
>false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled.
>
>The devlink->lock is held when devlink_dpipe_table_find()
>is called in non RCU read side section. Therefore, pass struct devlink
>to devlink_dpipe_table_find() for lockdep checking.
>
>Signed-off-by: Madhuparna Bhowmik <[email protected]>

Reviewed-by: Jiri Pirko <[email protected]>

2020-02-27 01:00:52

by David Miller

Subject: Re: [PATCH] net: core: devlink.c: Use built-in RCU list checking

From: [email protected]
Date: Tue, 25 Feb 2020 17:57:45 +0530

> From: Madhuparna Bhowmik <[email protected]>
>
> list_for_each_entry_rcu() has built-in RCU and lock checking.
>
> Pass cond argument to list_for_each_entry_rcu() to silence
> false lockdep warning when CONFIG_PROVE_RCU_LIST is enabled.
>
> The devlink->lock is held when devlink_dpipe_table_find()
> is called in non RCU read side section. Therefore, pass struct devlink
> to devlink_dpipe_table_find() for lockdep checking.
>
> Signed-off-by: Madhuparna Bhowmik <[email protected]>

Applied, thank you.