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wimax/i2400m: fix oops caused by race condition when exiting USB kthreads

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Current i2400m USB code had to threads (one for processing RX, one for
TX). When calling i2400m_{tx,rx}_release(), it would crash if the
thread had exited already due to an error.

So changed the code to have the thread fill in/out
i2400mu->{tx,rx}_kthread under a spinlock; then the _release()
function will call kthread_stop() only if {rx,tx}_kthread is still
set.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
This commit is contained in:
Inaky Perez-Gonzalez 2009-10-08 08:11:38 +09:00
parent 0c96859d7a
commit 4a78fd9a73
2 changed files with 59 additions and 11 deletions
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35
drivers/net/wimax/i2400m/usb-rx.c
View file

@ -316,10 +316,15 @@ int i2400mu_rxd(void *_i2400mu)
size_t pending;
int rx_size;
struct sk_buff *rx_skb;
unsigned long flags;
d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
spin_lock_irqsave(&i2400m->rx_lock, flags);
BUG_ON(i2400mu->rx_kthread != NULL);
i2400mu->rx_kthread = current;
spin_unlock_irqrestore(&i2400m->rx_lock, flags);
while (1) {
d_printf(2, dev, "TX: waiting for messages\n");
d_printf(2, dev, "RX: waiting for messages\n");
pending = 0;
wait_event_interruptible(
i2400mu->rx_wq,
@ -367,6 +372,9 @@ int i2400mu_rxd(void *_i2400mu)
}
result = 0;
out:
spin_lock_irqsave(&i2400m->rx_lock, flags);
i2400mu->rx_kthread = NULL;
spin_unlock_irqrestore(&i2400m->rx_lock, flags);
d_fnend(4, dev, "(i2400mu %p) = %d\n", i2400mu, result);
return result;
@ -403,18 +411,33 @@ int i2400mu_rx_setup(struct i2400mu *i2400mu)
struct i2400m *i2400m = &i2400mu->i2400m;
struct device *dev = &i2400mu->usb_iface->dev;
struct wimax_dev *wimax_dev = &i2400m->wimax_dev;
struct task_struct *kthread;
i2400mu->rx_kthread = kthread_run(i2400mu_rxd, i2400mu, "%s-rx",
wimax_dev->name);
if (IS_ERR(i2400mu->rx_kthread)) {
result = PTR_ERR(i2400mu->rx_kthread);
kthread = kthread_run(i2400mu_rxd, i2400mu, "%s-rx",
wimax_dev->name);
/* the kthread function sets i2400mu->rx_thread */
if (IS_ERR(kthread)) {
result = PTR_ERR(kthread);
dev_err(dev, "RX: cannot start thread: %d\n", result);
}
return result;
}
void i2400mu_rx_release(struct i2400mu *i2400mu)
{
kthread_stop(i2400mu->rx_kthread);
unsigned long flags;
struct i2400m *i2400m = &i2400mu->i2400m;
struct device *dev = i2400m_dev(i2400m);
struct task_struct *kthread;
spin_lock_irqsave(&i2400m->rx_lock, flags);
kthread = i2400mu->rx_kthread;
i2400mu->rx_kthread = NULL;
spin_unlock_irqrestore(&i2400m->rx_lock, flags);
if (kthread)
kthread_stop(kthread);
else
d_printf(1, dev, "RX: kthread had already exited\n");
}

35
drivers/net/wimax/i2400m/usb-tx.c
View file

@ -161,9 +161,15 @@ int i2400mu_txd(void *_i2400mu)
struct device *dev = &i2400mu->usb_iface->dev;
struct i2400m_msg_hdr *tx_msg;
size_t tx_msg_size;
unsigned long flags;
d_fnstart(4, dev, "(i2400mu %p)\n", i2400mu);
spin_lock_irqsave(&i2400m->tx_lock, flags);
BUG_ON(i2400mu->tx_kthread != NULL);
i2400mu->tx_kthread = current;
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
while (1) {
d_printf(2, dev, "TX: waiting for messages\n");
tx_msg = NULL;
@ -183,6 +189,11 @@ int i2400mu_txd(void *_i2400mu)
if (result < 0)
break;
}
spin_lock_irqsave(&i2400m->tx_lock, flags);
i2400mu->tx_kthread = NULL;
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
d_fnend(4, dev, "(i2400mu %p) = %d\n", i2400mu, result);
return result;
}
@ -213,11 +224,13 @@ int i2400mu_tx_setup(struct i2400mu *i2400mu)
struct i2400m *i2400m = &i2400mu->i2400m;
struct device *dev = &i2400mu->usb_iface->dev;
struct wimax_dev *wimax_dev = &i2400m->wimax_dev;
struct task_struct *kthread;
i2400mu->tx_kthread = kthread_run(i2400mu_txd, i2400mu, "%s-tx",
wimax_dev->name);
if (IS_ERR(i2400mu->tx_kthread)) {
result = PTR_ERR(i2400mu->tx_kthread);
kthread = kthread_run(i2400mu_txd, i2400mu, "%s-tx",
wimax_dev->name);
/* the kthread function sets i2400mu->tx_thread */
if (IS_ERR(kthread)) {
result = PTR_ERR(kthread);
dev_err(dev, "TX: cannot start thread: %d\n", result);
}
return result;
@ -225,5 +238,17 @@ int i2400mu_tx_setup(struct i2400mu *i2400mu)
void i2400mu_tx_release(struct i2400mu *i2400mu)
{
kthread_stop(i2400mu->tx_kthread);
unsigned long flags;
struct i2400m *i2400m = &i2400mu->i2400m;
struct device *dev = i2400m_dev(i2400m);
struct task_struct *kthread;
spin_lock_irqsave(&i2400m->tx_lock, flags);
kthread = i2400mu->tx_kthread;
i2400mu->tx_kthread = NULL;
spin_unlock_irqrestore(&i2400m->tx_lock, flags);
if (kthread)
kthread_stop(kthread);
else
d_printf(1, dev, "TX: kthread had already exited\n");
}