xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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

Browse Source 
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 d0e639c9e0
commit 702a4879ec
18 changed files with 33 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/spi/spi-bitbang.c
View File

@@ -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);