spi_pump_messages() calls into a controller driver with
unprepare_transfer_hardware() which is documented as "This may sleep".
As in the prepare_transfer_hardware() call below, we should release the
queue_lock spinlock before making the call.
Rework the logic a bit to hold queue_lock to protect the 'busy' flag,
then release it to call unprepare_transfer_hardware().

Signed-off-by: Bryan Freed <bfr...@chromium.org>

---
 drivers/spi/spi.c |   15 +++++++--------
 1 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index fc0da39..f7f9df9 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -532,17 +532,16 @@ static void spi_pump_messages(struct kthread_work *work)
        /* Lock queue and check for queue work */
        spin_lock_irqsave(&master->queue_lock, flags);
        if (list_empty(&master->queue) || !master->running) {
-               if (master->busy && master->unprepare_transfer_hardware) {
-                       ret = master->unprepare_transfer_hardware(master);
-                       if (ret) {
-                               spin_unlock_irqrestore(&master->queue_lock, 
flags);
-                               dev_err(&master->dev,
-                                       "failed to unprepare transfer 
hardware\n");
-                               return;
-                       }
+               if (!master->busy) {
+                       spin_unlock_irqrestore(&master->queue_lock, flags);
+                       return;
                }
                master->busy = false;
                spin_unlock_irqrestore(&master->queue_lock, flags);
+               if (master->unprepare_transfer_hardware &&
+                   master->unprepare_transfer_hardware(master))
+                       dev_err(&master->dev,
+                               "failed to unprepare transfer hardware\n");
                return;
        }
 
-- 
1.7.7.3


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