linux-kernel - [PATCH v3 7/9] scsi: ufs: Let host_sem cover the entire system suspend/resume

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Date:   Wed,  9 Jun 2021 21:43:35 -0700
From:   Can Guo <cang@...eaurora.org>
To:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        hongwus@...eaurora.org, ziqichen@...eaurora.org,
        linux-scsi@...r.kernel.org, kernel-team@...roid.com,
        cang@...eaurora.org
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kiwoong Kim <kwmad.kim@...sung.com>,
        Satya Tangirala <satyat@...gle.com>,
        Bart Van Assche <bvanassche@....org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v3 7/9] scsi: ufs: Let host_sem cover the entire system suspend/resume

UFS error handling now is doing more than just re-probing, but also sending
scsi cmds, e.g., for clearing UACs, and recovering runtime PM error, which
may change runtime status of scsi devices. To protect system suspend/resume
from being disturbed by error handling, move the host_sem from wl pm ops
to ufshcd_suspend_prepare() and ufshcd_resume_complete().

Signed-off-by: Can Guo <cang@...eaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 8 +++-----
 drivers/scsi/ufs/ufshcd.h | 2 +-
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index c418a19..861942b 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -9060,16 +9060,13 @@ static int ufshcd_wl_suspend(struct device *dev)
 	ktime_t start = ktime_get();
 
 	hba = shost_priv(sdev->host);
-	down(&hba->host_sem);
 
 	if (pm_runtime_suspended(dev))
 		goto out;
 
 	ret = __ufshcd_wl_suspend(hba, UFS_SYSTEM_PM);
-	if (ret) {
+	if (ret)
 		dev_err(&sdev->sdev_gendev, "%s failed: %d\n", __func__,  ret);
-		up(&hba->host_sem);
-	}
 
 out:
 	if (!ret)
@@ -9102,7 +9099,6 @@ static int ufshcd_wl_resume(struct device *dev)
 		hba->curr_dev_pwr_mode, hba->uic_link_state);
 	if (!ret)
 		hba->is_wl_sys_suspended = false;
-	up(&hba->host_sem);
 	return ret;
 }
 #endif
@@ -9665,6 +9661,7 @@ void ufshcd_resume_complete(struct device *dev)
 		ufshcd_rpmb_rpm_put(hba);
 		hba->rpmb_complete_put = false;
 	}
+	up(&hba->host_sem);
 }
 EXPORT_SYMBOL_GPL(ufshcd_resume_complete);
 
@@ -9691,6 +9688,7 @@ int ufshcd_suspend_prepare(struct device *dev)
 		ufshcd_rpmb_rpm_get_sync(hba);
 		hba->rpmb_complete_put = true;
 	}
+	down(&hba->host_sem);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ufshcd_suspend_prepare);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index eaebb4e..47da47c 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -693,7 +693,7 @@ struct ufs_hba_monitor {
  * @ee_ctrl_mask: Exception event control mask
  * @is_powered: flag to check if HBA is powered
  * @shutting_down: flag to check if shutdown has been invoked
- * @host_sem: semaphore used to serialize concurrent contexts
+ * @host_sem: semaphore used to avoid concurrency of contexts
  * @eh_wq: Workqueue that eh_work works on
  * @eh_work: Worker to handle UFS errors that require s/w attention
  * @eeh_work: Worker to handle exception events
-- 
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