From 702a4879ec337463f858c8ab467482cce260bf18 Mon Sep 17 00:00:00 2001 From: Axel Lin Date: Tue, 10 Sep 2013 15:43:41 +0800 Subject: 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 Suggested-by: Uwe Kleine-Koenig Acked-by: Uwe Kleine-Koenig Signed-off-by: Mark Brown --- drivers/spi/spi-bitbang.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'drivers/spi/spi-bitbang.c') diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index 8c11355..0056623 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -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); -- cgit v1.1