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From:   Can Guo <cang@codeaurora.org>
To:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        hongwus@codeaurora.org, ziqichen@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        cang@codeaurora.org
Cc:     Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v4 06/10] scsi: ufs: Remove host_sem used in suspend/resume
Date:   Wed, 23 Jun 2021 00:35:06 -0700
Message-Id: <1624433711-9339-8-git-send-email-cang@codeaurora.org>
In-Reply-To: <1624433711-9339-1-git-send-email-cang@codeaurora.org>
References: <1624433711-9339-1-git-send-email-cang@codeaurora.org>
Precedence: bulk

To protect system suspend/resume from being disturbed by error handling,
instead of using host_sem, let error handler call lock_system_sleep() and
unlock_system_sleep() which achieve the same purpose. Remove the host_sem
used in suspend/resume paths to make the code more readable.

Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 3695dd2..a09e4a2 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5907,6 +5907,11 @@ static void ufshcd_clk_scaling_suspend(struct ufs_hba *hba, bool suspend)
 
 static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 {
+	/*
+	 * It is not safe to perform error handling while suspend or resume is
+	 * in progress. Hence the lock_system_sleep() call.
+	 */
+	lock_system_sleep();
 	ufshcd_rpm_get_sync(hba);
 	if (pm_runtime_status_suspended(&hba->sdev_ufs_device->sdev_gendev) ||
 	    hba->is_wlu_sys_suspended) {
@@ -5951,6 +5956,7 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
 		ufshcd_clk_scaling_suspend(hba, false);
 	ufshcd_clear_ua_wluns(hba);
 	ufshcd_rpm_put(hba);
+	unlock_system_sleep();
 }
 
 static inline bool ufshcd_err_handling_should_stop(struct ufs_hba *hba)
@@ -9053,16 +9059,13 @@ 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)
@@ -9095,7 +9098,6 @@ static int ufshcd_wl_resume(struct device *dev)
 		hba->curr_dev_pwr_mode, hba->uic_link_state);
 	if (!ret)
 		hba->is_wlu_sys_suspended = false;
-	up(&hba->host_sem);
 	return ret;
 }
 #endif
-- 
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