[PATCH 2/5] scsi: ufs: core: Introduce ufshcd_rpm_resume_and_get() helper

[Stanley Jhu]

ufshcd_clkscale_enable_store() and ufshcd_auto_hibern8_update() call
ufshcd_rpm_get_sync() without checking its return value:

1. Runtime resume of the UFS device W-LUN fails and leaves the W-LUN in
   RPM_SUSPENDED, or a prior runtime suspend error latches
   power.runtime_error, or runtime PM is disabled while suspended so
   !pm_runtime_suspended() still evaluates to true.
2. ufshcd_rpm_get_sync() returns a negative errno and leaves
   power.usage_count incremented.
3. Both functions proceed as if the host were active, scaling clocks or
   writing REG_AUTO_HIBERNATE_IDLE_TIMER while the controller or link
   is still suspended.

Add ufshcd_rpm_resume_and_get() wrapping pm_runtime_resume_and_get() so
failed resumes drop the usage reference automatically, and return early
in ufshcd_clkscale_enable_store() and ufshcd_auto_hibern8_update() when
it fails.

Fixes: b294ff3e3449 ("scsi: ufs: core: Enable power management for wlun")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Stanley Jhu <stanleyjhu@xxxxxxxxxx>
---
 drivers/ufs/core/ufshcd-priv.h | 5 +++++
 drivers/ufs/core/ufshcd.c      | 7 +++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/ufs/core/ufshcd-priv.h b/drivers/ufs/core/ufshcd-priv.h
index e55c2a02c1f5..99f654b79035 100644
--- a/drivers/ufs/core/ufshcd-priv.h
+++ b/drivers/ufs/core/ufshcd-priv.h
@@ -388,6 +388,11 @@ static inline int ufshcd_rpm_get_sync(struct ufs_hba *hba)
 	return pm_runtime_get_sync(&hba->ufs_device_wlun->sdev_gendev);
 }
 
+static inline int ufshcd_rpm_resume_and_get(struct ufs_hba *hba)
+{
+	return pm_runtime_resume_and_get(&hba->ufs_device_wlun->sdev_gendev);
+}
+
 static inline int ufshcd_rpm_get_if_active(struct ufs_hba *hba)
 {
 	return pm_runtime_get_if_active(&hba->ufs_device_wlun->sdev_gendev);
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 5193be703752..2d73dc7d68a9 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1864,7 +1864,9 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 	if (value == hba->clk_scaling.is_enabled)
 		goto out;
 
-	ufshcd_rpm_get_sync(hba);
+	err = ufshcd_rpm_resume_and_get(hba);
+	if (err)
+		goto out;
 	ufshcd_hold(hba);
 
 	hba->clk_scaling.is_enabled = value;
@@ -4792,7 +4794,8 @@ void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
 
 	WRITE_ONCE(hba->ahit, ahit);
 	if (!pm_runtime_suspended(&hba->ufs_device_wlun->sdev_gendev)) {
-		ufshcd_rpm_get_sync(hba);
+		if (ufshcd_rpm_resume_and_get(hba))
+			return;
 		ufshcd_hold(hba);
 		/*
 		 * Serialize with the host driver's AHIT control. Skip the
-- 
2.56.0.307.g5fe7bd680c-goog