linux-kernel - [PATCH v2 3/3] scsi: ufs: Narrow down fast pass in system suspend path

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Date:   Sun, 25 Apr 2021 20:48:40 -0700
From:   Can Guo <cang@...eaurora.org>
To:     asutoshd@...eaurora.org, ziqichen@...eaurora.org,
        nguyenb@...eaurora.org, hongwus@...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>,
        Gilad Broner <gbroner@...eaurora.org>,
        Subhash Jadavani <subhashj@...eaurora.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 3/3] scsi: ufs: Narrow down fast pass in system suspend path

If spm_lvl is set to 0 or 1, when system suspend kicks start and hba is
runtime active, system suspend may just bail without doing anything (the
fast pass), leaving other contexts still running, e.g., clock gating and
clock scaling. When system resume kicks start, concurrency can happen btw
ufshcd_resume() and these contexts, leading to various stability issues.
Fix it by adding a check against hba's runtime status and allowing fast
pass only if hba is runtime suspended, otherwise let system suspend go
ahead call ufshcd_suspend(). This can guarantee that these contexts are
stopped by either runtime suspend or system suspend.

Fixes: 0b257734344aa ("scsi: ufs: optimize system suspend handling")
Signed-off-by: Can Guo <cang@...eaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a2f9c8e..c480f88 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -9050,6 +9050,7 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
 	     hba->curr_dev_pwr_mode) &&
 	    (ufs_get_pm_lvl_to_link_pwr_state(hba->spm_lvl) ==
 	     hba->uic_link_state) &&
+	     pm_runtime_suspended(hba->dev) &&
 	     !hba->dev_info.b_rpm_dev_flush_capable)
 		goto out;
 
-- 
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