soundwire: bus: Fix unbalanced pm_runtime_put() causing usage count underflow
authorRichard Fitzgerald <rf@opensource.cirrus.com>
Thu, 6 Apr 2023 13:46:40 +0000 (14:46 +0100)
committerVinod Koul <vkoul@kernel.org>
Wed, 12 Apr 2023 10:04:40 +0000 (15:34 +0530)
commite9537962519e88969f5f69cd0571eb4f6984403c
tree7c9cf5929b2435335053cdc2ca9610cf18e648dd
parent0a0d1740bd8fd7dafb81fcb102fb5d0b83b1ce73
soundwire: bus: Fix unbalanced pm_runtime_put() causing usage count underflow

This reverts commit
443a98e649b4 ("soundwire: bus: use pm_runtime_resume_and_get()")

Change calls to pm_runtime_resume_and_get() back to pm_runtime_get_sync().
This fixes a usage count underrun caused by doing a pm_runtime_put() even
though pm_runtime_resume_and_get() returned an error.

The three affected functions ignore -EACCES error from trying to get
pm_runtime, and carry on, including a put at the end of the function.
But pm_runtime_resume_and_get() does not increment the usage count if it
returns an error. So in the -EACCES case you must not call
pm_runtime_put().

The documentation for pm_runtime_get_sync() says:
 "Consider using pm_runtime_resume_and_get() ...  as this is likely to
 result in cleaner code."

In this case I don't think it results in cleaner code because the
pm_runtime_put() at the end of the function would have to be conditional on
the return value from pm_runtime_resume_and_get() at the top of the
function.

pm_runtime_get_sync() doesn't have this problem because it always
increments the count, so always needs a put. The code can just flow through
and do the pm_runtime_put() unconditionally.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20230406134640.8582-1-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
drivers/soundwire/bus.c