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>

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index e157a39a82ce58fb9047e3ea96a7deafcfb6cd35..1ea6a64f8c4a5e0a2ba6193fd81dd3a6c9e48fa0 100644 (file)
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -584,9 +584,11 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
 {
        int ret;
 
-       ret = pm_runtime_resume_and_get(&slave->dev);
-       if (ret < 0 && ret != -EACCES)
+       ret = pm_runtime_get_sync(&slave->dev);
+       if (ret < 0 && ret != -EACCES) {
+               pm_runtime_put_noidle(&slave->dev);
                return ret;
+       }
 
        ret = sdw_nread_no_pm(slave, addr, count, val);
 
@@ -613,9 +615,11 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
 {
        int ret;
 
-       ret = pm_runtime_resume_and_get(&slave->dev);
-       if (ret < 0 && ret != -EACCES)
+       ret = pm_runtime_get_sync(&slave->dev);
+       if (ret < 0 && ret != -EACCES) {
+               pm_runtime_put_noidle(&slave->dev);
                return ret;
+       }
 
        ret = sdw_nwrite_no_pm(slave, addr, count, val);
 
@@ -1590,9 +1594,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
 
        sdw_modify_slave_status(slave, SDW_SLAVE_ALERT);
 
-       ret = pm_runtime_resume_and_get(&slave->dev);
+       ret = pm_runtime_get_sync(&slave->dev);
        if (ret < 0 && ret != -EACCES) {
                dev_err(&slave->dev, "Failed to resume device: %d\n", ret);
+               pm_runtime_put_noidle(&slave->dev);
                return ret;
        }