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authorAxel Lin <axel.lin@ingics.com>2013-09-10 15:43:41 +0800
committerMark Brown <broonie@linaro.org>2013-10-07 14:50:43 +0100
commit702a4879ec337463f858c8ab467482cce260bf18 (patch)
treee726356d57e6be815e201d12694a82c461a636e3 /drivers/spi/spi-bitbang.c
parentd0e639c9e06d44e713170031fe05fb60ebe680af (diff)
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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>
Diffstat (limited to 'drivers/spi/spi-bitbang.c')
-rw-r--r--drivers/spi/spi-bitbang.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index 8c11355dec23..0056623dfc6b 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);