2020-02-24 09:32:25

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 | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index e82750bdc496..dadf5fa79bb1 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 +6845,7 @@ 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 +6881,7 @@ 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 +7038,7 @@ 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

2020-02-24 10:53:05

by Jiri Pirko

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

Mon, Feb 24, 2020 at 10:30:13AM 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]>
>---
> net/core/devlink.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
>diff --git a/net/core/devlink.c b/net/core/devlink.c
>index e82750bdc496..dadf5fa79bb1 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 +6845,7 @@ 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)) {

Run scripts/checkpatch.pl on your patch. You are breaking 80-cols limit
here.

Otherwise, the patch looks fine.

> err = -EEXIST;
> goto unlock;
> }
>@@ -6881,7 +6881,7 @@ 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 +7038,7 @@ 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 12:15:23

by Madhuparna Bhowmik

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

On Mon, Feb 24, 2020 at 11:52:09AM +0100, Jiri Pirko wrote:
> Mon, Feb 24, 2020 at 10:30:13AM 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]>
> >---
> > net/core/devlink.c | 18 +++++++++---------
> > 1 file changed, 9 insertions(+), 9 deletions(-)
> >
> >diff --git a/net/core/devlink.c b/net/core/devlink.c
> >index e82750bdc496..dadf5fa79bb1 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 +6845,7 @@ 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)) {
>
> Run scripts/checkpatch.pl on your patch. You are breaking 80-cols limit
> here.
>
Sure, I will take care of this and send the updated patch soon.

Thank you,
Madhuparna
> Otherwise, the patch looks fine.
>
> > err = -EEXIST;
> > goto unlock;
> > }
> >@@ -6881,7 +6881,7 @@ 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 +7038,7 @@ 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
> >