diff options
| author | Solomon Peachy <pizza@shaftnet.org> | 2013-08-27 20:29:47 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-01 09:41:02 -0700 |
| commit | 524a992af32af99a4fa8521640ba5bb38fde41d1 (patch) | |
| tree | 49756746b8f271dbba429aad153417f175b94cdb | |
| parent | 4179ebecdc904aef8625afc1c227a2b591c5ed44 (diff) | |
cw1200: Prevent a lock-related hang in the cw1200_spi driver
commit 85ba8f529c57ac6e2fca9be0d9e17920a1afb2e8 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/wireless/cw1200/cw1200_spi.c | 9 |
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 d06376014bcd..5a64ac963009 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; }; @@ -197,8 +198,11 @@ 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); @@ -211,6 +215,7 @@ 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; } @@ -222,6 +227,8 @@ 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; } @@ -400,6 +407,8 @@ 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, |