linux-kernel - [PATCH v1 5/5] scsi: ufs: Complete pending requests in host reset and restore path

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Message-Id: <1573200932-384-6-git-send-email-cang@codeaurora.org>
Date:   Fri,  8 Nov 2019 00:15:31 -0800
From:   Can Guo <cang@...eaurora.org>
To:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        cang@...eaurora.org
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Pedro Sousa <pedrom.sousa@...opsys.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>,
        Subhash Jadavani <subhashj@...eaurora.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v1 5/5] scsi: ufs: Complete pending requests in host reset and restore path

In UFS host reset and restore path, before probe, we stop and start the
host controller once. After host controller is stopped, the pending
requests, if any, are cleared from the doorbell, but no completion IRQ
would be raised due to the hba is stopped.
These pending requests shall be completed along with the first NOP_OUT
command(as it is the first command which can raise a transfer completion
IRQ) sent during probe.
Since the OCSs of these pending requests are not SUCCESS(because they are
not yet literally finished), their UPIUs shall be dumped. When there are
multiple pending requests, the UPIU dump can be overwhelming and may lead
to stability issues because it is in atomic context.
Therefore, before probe, complete these pending requests right after host
controller is stopped.

Signed-off-by: Can Guo <cang@...eaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 5950a7c..4df4136 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5404,8 +5404,8 @@ static void ufshcd_err_handler(struct work_struct *work)
 
 	/*
 	 * if host reset is required then skip clearing the pending
-	 * transfers forcefully because they will automatically get
-	 * cleared after link startup.
+	 * transfers forcefully because they will get cleared during
+	 * host reset and restore
 	 */
 	if (needs_reset)
 		goto skip_pending_xfer_clear;
@@ -6333,9 +6333,13 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
 	int err;
 	unsigned long flags;
 
-	/* Reset the host controller */
+	/*
+	 * Stop the host controller and complete the requests
+	 * cleared by h/w
+	 */
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	ufshcd_hba_stop(hba, false);
+	ufshcd_complete_requests(hba);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
 	/* scale up clocks to max frequency before full reinitialization */
@@ -6369,7 +6373,6 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
 static int ufshcd_reset_and_restore(struct ufs_hba *hba)
 {
 	int err = 0;
-	unsigned long flags;
 	int retries = MAX_HOST_RESET_RETRIES;
 
 	do {
@@ -6379,15 +6382,6 @@ static int ufshcd_reset_and_restore(struct ufs_hba *hba)
 		err = ufshcd_host_reset_and_restore(hba);
 	} while (err && --retries);
 
-	/*
-	 * After reset the door-bell might be cleared, complete
-	 * outstanding requests in s/w here.
-	 */
-	spin_lock_irqsave(hba->host->host_lock, flags);
-	ufshcd_transfer_req_compl(hba);
-	ufshcd_tmc_handler(hba);
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
-
 	return err;
 }
 
-- 
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