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authorSolomon Peachy <pizza@shaftnet.org>2013-08-27 20:29:47 -0400
committerJohn W. Linville <linville@tuxdriver.com>2013-09-09 14:40:54 -0400
commit85ba8f529c57ac6e2fca9be0d9e17920a1afb2e8 (patch)
treebb22dd1b9f6e5b442d3c6c2bad87476baa4b9e0f /drivers/net/wireless/cw1200
parentaec8e88c947b7017e2b4bbcb68a4bfc4a1f8ad35 (diff)
cw1200: Prevent a lock-related hang in the cw1200_spi driver
The cw1200_spi driver tries to mirror the cw1200_sdio driver's lock API, which relies on sdio_claim_host/sdio_release_host to serialize hardware operations across multiple threads. Unfortunately the implementation was flawed, as it lacked a way to wake up the lock requestor when there was contention, often resulting in a hang. This problem was uncovered while trying to fix the spi-transfers-in-interrupt-context BUG() corrected in the previous patch. Many thanks to Dave Sizeburns for his assistance in fixing this. Signed-off-by: Solomon Peachy <pizza@shaftnet.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'drivers/net/wireless/cw1200')
-rw-r--r--drivers/net/wireless/cw1200/cw1200_spi.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/net/wireless/cw1200/cw1200_spi.c b/drivers/net/wireless/cw1200/cw1200_spi.c
index c31580ba883b..f5e6b489ed32 100644
--- a/drivers/net/wireless/cw1200/cw1200_spi.c
+++ b/drivers/net/wireless/cw1200/cw1200_spi.c
@@ -40,6 +40,7 @@ struct hwbus_priv {
struct cw1200_common *core;
const struct cw1200_platform_data_spi *pdata;
spinlock_t lock; /* Serialize all bus operations */
+ wait_queue_head_t wq;
int claimed;
int irq_disabled;
};
@@ -198,8 +199,11 @@ static void cw1200_spi_lock(struct hwbus_priv *self)
{
unsigned long flags;
+ DECLARE_WAITQUEUE(wait, current);
+
might_sleep();
+ add_wait_queue(&self->wq, &wait);
spin_lock_irqsave(&self->lock, flags);
while (1) {
set_current_state(TASK_UNINTERRUPTIBLE);
@@ -212,6 +216,7 @@ static void cw1200_spi_lock(struct hwbus_priv *self)
set_current_state(TASK_RUNNING);
self->claimed = 1;
spin_unlock_irqrestore(&self->lock, flags);
+ remove_wait_queue(&self->wq, &wait);
return;
}
@@ -223,6 +228,8 @@ static void cw1200_spi_unlock(struct hwbus_priv *self)
spin_lock_irqsave(&self->lock, flags);
self->claimed = 0;
spin_unlock_irqrestore(&self->lock, flags);
+ wake_up(&self->wq);
+
return;
}
@@ -413,6 +420,8 @@ static int cw1200_spi_probe(struct spi_device *func)
spi_set_drvdata(func, self);
+ init_waitqueue_head(&self->wq);
+
status = cw1200_spi_irq_subscribe(self);
status = cw1200_core_probe(&cw1200_spi_hwbus_ops,