Commit 702a4879 authored by Axel Lin's avatar Axel Lin Committed by Mark Brown
Browse files

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: default avatarAxel Lin <axel.lin@ingics.com>
Suggested-by: default avatarUwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Acked-by: default avatarUwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarMark Brown <broonie@linaro.org>
parent d0e639c9

drivers/spi/spi-altera.c

+1 −1
Original line number Diff line number Diff line
@@ -219,7 +219,7 @@ static int altera_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.chipselect = altera_spi_chipsel;

drivers/spi/spi-ath79.c

+1 −1
Original line number Diff line number Diff line
@@ -231,7 +231,7 @@ static int ath79_spi_probe(struct platform_device *pdev) 
		master->num_chipselect = pdata->num_chipselect;

	}



	sp->bitbang.master = spi_master_get(master);

	sp->bitbang.master = master;

	sp->bitbang.chipselect = ath79_spi_chipselect;

	sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;

	sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;

drivers/spi/spi-au1550.c

+1 −1
Original line number Diff line number Diff line
@@ -775,7 +775,7 @@ static int au1550_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;

drivers/spi/spi-bitbang.c

+11 −1
Original line number Diff line number Diff line
@@ -414,10 +414,16 @@ static int spi_bitbang_unprepare_hardware(struct spi_master *spi) 
 * This routine registers the spi_master, which will process requests in a

 * dedicated task, keeping IRQs unblocked most of the time.  To stop

 * processing those requests, call spi_bitbang_stop().

 *

 * On success, this routine will take a reference to master. 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.

 */

int spi_bitbang_start(struct spi_bitbang *bitbang)

{

	struct spi_master *master = bitbang->master;

	int ret;



	if (!master || !bitbang->chipselect)

		return -EINVAL;
@@ -449,7 +455,11 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) 
	/* driver may get busy before register() returns, especially

	 * if someone registered boardinfo for devices

	 */

	return spi_register_master(master);

	ret = spi_register_master(spi_master_get(master));

	if (ret)

		spi_master_put(master);



	return 0;

}

EXPORT_SYMBOL_GPL(spi_bitbang_start);

drivers/spi/spi-butterfly.c

+1 −1
Original line number Diff line number Diff line
@@ -225,7 +225,7 @@ static void butterfly_attach(struct parport *p) 
	master->bus_num = 42;

	master->num_chipselect = 2;



	pp->bitbang.master = spi_master_get(master);

	pp->bitbang.master = master;

	pp->bitbang.chipselect = butterfly_chipselect;

	pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;

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