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

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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>
This commit is contained in:
Axel Lin
2013-09-10 15:43:41 +08:00
committed by Mark Brown
parent 272b98c645
commit 94c69f765f
18 changed files with 33 additions and 26 deletions
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2
drivers/spi/spi-oc-tiny.c
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@@ -306,7 +306,7 @@ static int tiny_spi_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, hw);
/* setup the state for the bitbang driver */
hw->bitbang.master = spi_master_get(master);
hw->bitbang.master = master;
if (!hw->bitbang.master)
return err;
hw->bitbang.setup_transfer = tiny_spi_setup_transfer;