2014-04-29 18:38:34

by Libor Pechacek

Subject: [PATCH] rfcomm: Convert spinlocks into mutexes

Enabling CONFIG_DEBUG_ATOMIC_SLEEP has shown that some rfcomm functions
acquiring spinlocks call sleeping locks further in the chain. Converting
the offending spinlocks into mutexes makes sleeping safe.

Signed-off-by: Libor Pechacek <[email protected]>
---
include/net/bluetooth/rfcomm.h | 6 +++---
net/bluetooth/rfcomm/core.c | 2 +-
net/bluetooth/rfcomm/tty.c | 20 ++++++++++----------
3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h
index 2611cc389d7d..578b83127af1 100644
--- a/include/net/bluetooth/rfcomm.h
+++ b/include/net/bluetooth/rfcomm.h
@@ -173,7 +173,7 @@ struct rfcomm_dlc {
struct sk_buff_head tx_queue;
struct timer_list timer;

- spinlock_t lock;
+ struct mutex lock;
unsigned long state;
unsigned long flags;
atomic_t refcnt;
@@ -244,8 +244,8 @@ int rfcomm_dlc_get_modem_status(struct rfcomm_dlc *d, u8 *v24_sig);
void rfcomm_dlc_accept(struct rfcomm_dlc *d);
struct rfcomm_dlc *rfcomm_dlc_exists(bdaddr_t *src, bdaddr_t *dst, u8 channel);

-#define rfcomm_dlc_lock(d) spin_lock(&d->lock)
-#define rfcomm_dlc_unlock(d) spin_unlock(&d->lock)
+#define rfcomm_dlc_lock(d) mutex_lock(&d->lock)
+#define rfcomm_dlc_unlock(d) mutex_unlock(&d->lock)

static inline void rfcomm_dlc_hold(struct rfcomm_dlc *d)
{
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index cf620260affa..754b6fe4f742 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -307,7 +307,7 @@ struct rfcomm_dlc *rfcomm_dlc_alloc(gfp_t prio)
setup_timer(&d->timer, rfcomm_dlc_timeout, (unsigned long)d);

skb_queue_head_init(&d->tx_queue);
- spin_lock_init(&d->lock);
+ mutex_init(&d->lock);
atomic_set(&d->refcnt, 1);

rfcomm_dlc_clear_state(d);
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 403ec09f480a..8e385a0ae60e 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -70,7 +70,7 @@ struct rfcomm_dev {
};

static LIST_HEAD(rfcomm_dev_list);
-static DEFINE_SPINLOCK(rfcomm_dev_lock);
+static DEFINE_MUTEX(rfcomm_dev_lock);

static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc, struct sk_buff *skb);
static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err);
@@ -96,9 +96,9 @@ static void rfcomm_dev_destruct(struct tty_port *port)
if (dev->tty_dev)
tty_unregister_device(rfcomm_tty_driver, dev->id);

- spin_lock(&rfcomm_dev_lock);
+ mutex_lock(&rfcomm_dev_lock);
list_del(&dev->list);
- spin_unlock(&rfcomm_dev_lock);
+ mutex_unlock(&rfcomm_dev_lock);

kfree(dev);

@@ -161,14 +161,14 @@ static struct rfcomm_dev *rfcomm_dev_get(int id)
{
struct rfcomm_dev *dev;

- spin_lock(&rfcomm_dev_lock);
+ mutex_lock(&rfcomm_dev_lock);

dev = __rfcomm_dev_lookup(id);

if (dev && !tty_port_get(&dev->port))
dev = NULL;

- spin_unlock(&rfcomm_dev_lock);
+ mutex_unlock(&rfcomm_dev_lock);

return dev;
}
@@ -224,7 +224,7 @@ static struct rfcomm_dev *__rfcomm_dev_add(struct rfcomm_dev_req *req,
if (!dev)
return ERR_PTR(-ENOMEM);

- spin_lock(&rfcomm_dev_lock);
+ mutex_lock(&rfcomm_dev_lock);

if (req->dev_id < 0) {
dev->id = 0;
@@ -305,11 +305,11 @@ static struct rfcomm_dev *__rfcomm_dev_add(struct rfcomm_dev_req *req,
holds reference to this module. */
__module_get(THIS_MODULE);

- spin_unlock(&rfcomm_dev_lock);
+ mutex_unlock(&rfcomm_dev_lock);
return dev;

out:
- spin_unlock(&rfcomm_dev_lock);
+ mutex_unlock(&rfcomm_dev_lock);
kfree(dev);
return ERR_PTR(err);
}
@@ -524,7 +524,7 @@ static int rfcomm_get_dev_list(void __user *arg)

di = dl->dev_info;

- spin_lock(&rfcomm_dev_lock);
+ mutex_lock(&rfcomm_dev_lock);

list_for_each_entry(dev, &rfcomm_dev_list, list) {
if (!tty_port_get(&dev->port))
@@ -540,7 +540,7 @@ static int rfcomm_get_dev_list(void __user *arg)
break;
}

- spin_unlock(&rfcomm_dev_lock);
+ mutex_unlock(&rfcomm_dev_lock);

dl->dev_num = n;
size = sizeof(*dl) + n * sizeof(*di);
--
1.7.12.4

2014-05-06 02:25:50

by Marcel Holtmann

Subject: Re: [PATCH] rfcomm: Convert spinlocks into mutexes

Hi Libor,

> Enabling CONFIG_DEBUG_ATOMIC_SLEEP has shown that some rfcomm functions
> acquiring spinlocks call sleeping locks further in the chain. Converting
> the offending spinlocks into mutexes makes sleeping safe.
>
> Signed-off-by: Libor Pechacek <[email protected]>
> ---
> include/net/bluetooth/rfcomm.h | 6 +++---
> net/bluetooth/rfcomm/core.c | 2 +-
> net/bluetooth/rfcomm/tty.c | 20 ++++++++++----------
> 3 files changed, 14 insertions(+), 14 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel