[PATCH] spi: destroy workqueue after spi_unregister_master

Fix a bug in the cleanup of an spi_bitbang bus.

The workqueue associated with the bus was destroyed before the call to
spi_unregister_master.  That meant that spi devices on that bus would be
unable to do IO in their remove method.  The shutdown flag should have been
able to prevent a segfault, but was never getting set.  By waiting to
destroy the workqueue until after the master is unregistered, devices are
able to do IO in their remove methods.  An added benefit is that neither
the shutdown flag nor a wait for the queue of messages to empty is needed.

Signed-off-by: Chris Lesiak <chris.lesiak@licor.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index 24a330d82395a6e260c9ae5bdc7bb6132bb7c477..88425e1af4d353fcc0ce14c0dd29c130c770f7f1 100644 (file)
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -302,10 +302,6 @@ static void bitbang_work(struct work_struct *work)
                setup_transfer = NULL;
 
                list_for_each_entry (t, &m->transfers, transfer_list) {
-                       if (bitbang->shutdown) {
-                               status = -ESHUTDOWN;
-                               break;
-                       }
 
                        /* override or restore speed and wordsize */
                        if (t->speed_hz || t->bits_per_word) {
@@ -410,8 +406,6 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
        m->status = -EINPROGRESS;
 
        bitbang = spi_master_get_devdata(spi->master);
-       if (bitbang->shutdown)
-               return -ESHUTDOWN;
 
        spin_lock_irqsave(&bitbang->lock, flags);
        if (!spi->max_speed_hz)
@@ -507,28 +501,12 @@ EXPORT_SYMBOL_GPL(spi_bitbang_start);
  */
 int spi_bitbang_stop(struct spi_bitbang *bitbang)
 {
-       unsigned        limit = 500;
-
-       spin_lock_irq(&bitbang->lock);
-       bitbang->shutdown = 0;
-       while (!list_empty(&bitbang->queue) && limit--) {
-               spin_unlock_irq(&bitbang->lock);
+       spi_unregister_master(bitbang->master);
 
-               dev_dbg(bitbang->master->cdev.dev, "wait for queue\n");
-               msleep(10);
-
-               spin_lock_irq(&bitbang->lock);
-       }
-       spin_unlock_irq(&bitbang->lock);
-       if (!list_empty(&bitbang->queue)) {
-               dev_err(bitbang->master->cdev.dev, "queue didn't empty\n");
-               return -EBUSY;
-       }
+       WARN_ON(!list_empty(&bitbang->queue));
 
        destroy_workqueue(bitbang->workqueue);
 
-       spi_unregister_master(bitbang->master);
-
        return 0;
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_stop);

diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index 2e8c048b9b80f9bf539c96a7dcf12a5d86bad27f..9dbca629dcfbfb2f401965e9a4ff87ddda38ce2c 100644 (file)
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -25,7 +25,6 @@ struct spi_bitbang {
        spinlock_t              lock;
        struct list_head        queue;
        u8                      busy;
-       u8                      shutdown;
        u8                      use_dma;
 
        struct spi_master       *master;