The cw1200_spi driver tries to mirror the cw1200_sdio driver's locking 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, resulting in a hang. Signed-off-by: Solomon Peachy <[email protected]> --- drivers/net/wireless/cw1200/cw1200_spi.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/wireless/cw1200/cw1200_spi.c b/drivers/net/wireless/cw1200/cw1200_spi.c index c31580b..f5e6b48 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, -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
