2020-02-25 13:13:40

by Madhuparna Bhowmik

Subject: [PATCH] net: bluetooth: hci_core: Fix Suspicious RCU usage warnings

From: Madhuparna Bhowmik <[email protected]>

The following functions in hci_core are always called with
hdev->lock held. No need to use list_for_each_entry_rcu(), therefore
change the usage of list_for_each_entry_rcu() in these functions
to list_for_each_entry().

hci_link_keys_clear()
hci_smp_ltks_clear()
hci_smp_irks_clear()
hci_blocked_keys_clear()

Warning encountered with CONFIG_PROVE_RCU_LIST:

[ 72.213184] =============================
[ 72.213188] WARNING: suspicious RCU usage
[ 72.213192] 5.6.0-rc1+ #5 Not tainted
[ 72.213195] -----------------------------
[ 72.213198] net/bluetooth/hci_core.c:2288 RCU-list traversed in non-reader section!!

[ 72.213676] =============================
[ 72.213679] WARNING: suspicious RCU usage
[ 72.213683] 5.6.0-rc1+ #5 Not tainted
[ 72.213685] -----------------------------
[ 72.213689] net/bluetooth/hci_core.c:2298 RCU-list traversed in non-reader section!!

[ 72.214195] =============================
[ 72.214198] WARNING: suspicious RCU usage
[ 72.214201] 5.6.0-rc1+ #5 Not tainted
[ 72.214204] -----------------------------
[ 72.214208] net/bluetooth/hci_core.c:2308 RCU-list traversed in non-reader section!!

[ 333.456972] =============================
[ 333.456979] WARNING: suspicious RCU usage
[ 333.457001] 5.6.0-rc1+ #5 Not tainted
[ 333.457007] -----------------------------
[ 333.457014] net/bluetooth/hci_core.c:2318 RCU-list traversed in non-reader section!!

Signed-off-by: Madhuparna Bhowmik <[email protected]>
---
net/bluetooth/hci_core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index cbbc34a006d1..8ddd1bea02be 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2285,7 +2285,7 @@ void hci_link_keys_clear(struct hci_dev *hdev)
{
struct link_key *key;

- list_for_each_entry_rcu(key, &hdev->link_keys, list) {
+ list_for_each_entry(key, &hdev->link_keys, list) {
list_del_rcu(&key->list);
kfree_rcu(key, rcu);
}
@@ -2295,7 +2295,7 @@ void hci_smp_ltks_clear(struct hci_dev *hdev)
{
struct smp_ltk *k;

- list_for_each_entry_rcu(k, &hdev->long_term_keys, list) {
+ list_for_each_entry(k, &hdev->long_term_keys, list) {
list_del_rcu(&k->list);
kfree_rcu(k, rcu);
}
@@ -2305,7 +2305,7 @@ void hci_smp_irks_clear(struct hci_dev *hdev)
{
struct smp_irk *k;

- list_for_each_entry_rcu(k, &hdev->identity_resolving_keys, list) {
+ list_for_each_entry(k, &hdev->identity_resolving_keys, list) {
list_del_rcu(&k->list);
kfree_rcu(k, rcu);
}
@@ -2315,7 +2315,7 @@ void hci_blocked_keys_clear(struct hci_dev *hdev)
{
struct blocked_key *b;

- list_for_each_entry_rcu(b, &hdev->blocked_keys, list) {
+ list_for_each_entry(b, &hdev->blocked_keys, list) {
list_del_rcu(&b->list);
kfree_rcu(b, rcu);
}
--
2.17.1

2020-02-28 07:37:34

by Marcel Holtmann

Subject: Re: [PATCH] net: bluetooth: hci_core: Fix Suspicious RCU usage warnings

Hi Madhuparna,

> The following functions in hci_core are always called with
> hdev->lock held. No need to use list_for_each_entry_rcu(), therefore
> change the usage of list_for_each_entry_rcu() in these functions
> to list_for_each_entry().
>
> hci_link_keys_clear()
> hci_smp_ltks_clear()
> hci_smp_irks_clear()
> hci_blocked_keys_clear()
>
> Warning encountered with CONFIG_PROVE_RCU_LIST:
>
> [ 72.213184] =============================
> [ 72.213188] WARNING: suspicious RCU usage
> [ 72.213192] 5.6.0-rc1+ #5 Not tainted
> [ 72.213195] -----------------------------
> [ 72.213198] net/bluetooth/hci_core.c:2288 RCU-list traversed in non-reader section!!
>
> [ 72.213676] =============================
> [ 72.213679] WARNING: suspicious RCU usage
> [ 72.213683] 5.6.0-rc1+ #5 Not tainted
> [ 72.213685] -----------------------------
> [ 72.213689] net/bluetooth/hci_core.c:2298 RCU-list traversed in non-reader section!!
>
> [ 72.214195] =============================
> [ 72.214198] WARNING: suspicious RCU usage
> [ 72.214201] 5.6.0-rc1+ #5 Not tainted
> [ 72.214204] -----------------------------
> [ 72.214208] net/bluetooth/hci_core.c:2308 RCU-list traversed in non-reader section!!
>
> [ 333.456972] =============================
> [ 333.456979] WARNING: suspicious RCU usage
> [ 333.457001] 5.6.0-rc1+ #5 Not tainted
> [ 333.457007] -----------------------------
> [ 333.457014] net/bluetooth/hci_core.c:2318 RCU-list traversed in non-reader section!!
>
> Signed-off-by: Madhuparna Bhowmik <[email protected]>
> ---
> net/bluetooth/hci_core.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel