[PATCH 4.14 007/242] scsi: ufs: Make sure clk scaling happens only when HBA is runtime ACTIVE

Greg Kroah-Hartman
2020-12-28T13:08:41Z

From: Can Guo <cang@codeaurora.org>

[ Upstream commit 73cc291c270248567245f084dcdf5078069af6b5 ]

If someone plays with the UFS clk scaling devfreq governor through sysfs,
ufshcd_devfreq_scale may be called even when HBA is not runtime ACTIVE.
This can lead to unexpected error. We cannot just protect it by calling
pm_runtime_get_sync() because that may cause a race condition since HBA
runtime suspend ops need to suspend clk scaling. To fix this call
pm_runtime_get_noresume() and check HBA's runtime status. Only proceed if
HBA is runtime ACTIVE, otherwise just bail.

governor_store
devfreq_performance_handler
update_devfreq
devfreq_set_target
ufshcd_devfreq_target
ufshcd_devfreq_scale

Link: https://lore.kernel.org/r/1600758548-28576-1-git-send-email-cang@codeaurora.org
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/ufs/ufshcd.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a3a3ee6e2a002..342e086e41991 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1215,8 +1215,15 @@ static int ufshcd_devfreq_target(struct device *dev,
}
spin_unlock_irqrestore(hba->host->host_lock, irq_flags);

+ pm_runtime_get_noresume(hba->dev);
+ if (!pm_runtime_active(hba->dev)) {
+ pm_runtime_put_noidle(hba->dev);
+ ret = -EAGAIN;
+ goto out;
+ }
start = ktime_get();
ret = ufshcd_devfreq_scale(hba, scale_up);
+ pm_runtime_put(hba->dev);

trace_ufshcd_profile_clk_scaling(dev_name(hba->dev),
(scale_up ? "up" : "down"),
--
2.27.0