spi: bitbang: Let spi_bitbang_start() take a reference to master

Many drivers that use bitbang library have a leak on probe error paths.
This is because once a spi_master_get() call succeeds, we need an additional
spi_master_put() call to free the memory.

Fix this issue by moving the code taking a reference to master to
spi_bitbang_start(), so spi_bitbang_start() will take a reference to master on
success. With this change, the caller is responsible for calling
spi_bitbang_stop() to decrement the reference and spi_master_put() as
counterpart of spi_alloc_master() to prevent a memory leak.

So now we have below patten for drivers using bitbang library:

probe:
spi_alloc_master        -> Init reference count to 1
spi_bitbang_start       -> Increment reference count
remove:
spi_bitbang_stop        -> Decrement reference count
spi_master_put          -> Decrement reference count (reference count reaches 0)

Fixup all users accordingly.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Suggested-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Acked-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/spi/spi-nuc900.c b/drivers/spi/spi-nuc900.c
index 47a68b43bcd5..e0c32bc69ee2 100644
--- a/drivers/spi/spi-nuc900.c
+++ b/drivers/spi/spi-nuc900.c
@@ -349,7 +349,7 @@ static int nuc900_spi_probe(struct platform_device *pdev)
 	}
 
 	hw = spi_master_get_devdata(master);
-	hw->master = spi_master_get(master);
+	hw->master = master;
 	hw->pdata  = dev_get_platdata(&pdev->dev);
 	hw->dev = &pdev->dev;
 
@@ -435,7 +435,6 @@ err_iomap:
 	kfree(hw->ioarea);
 err_pdata:
 	spi_master_put(hw->master);
-
 err_nomem:
 	return err;
 }