linux-kernel - [PATCH AUTOSEL 4.19 051/206] scsi: ufs: Fix a race condition in the tracing code

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Date:   Thu, 17 Sep 2020 22:05:27 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Bart Van Assche <bvanassche@....org>,
        Bean Huo <beanhuo@...ron.com>, Can Guo <cang@...eaurora.org>,
        Avri Altman <avri.altman@....com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>, linux-scsi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH AUTOSEL 4.19 051/206] scsi: ufs: Fix a race condition in the tracing code

From: Bart Van Assche <bvanassche@....org>

[ Upstream commit eacf36f5bebde5089dddb3d5bfcbeab530b01f8a ]

Starting execution of a command before tracing a command may cause the
completion handler to free data while it is being traced. Fix this race by
tracing a command before it is submitted.

Cc: Bean Huo <beanhuo@...ron.com>
Cc: Can Guo <cang@...eaurora.org>
Cc: Avri Altman <avri.altman@....com>
Cc: Stanley Chu <stanley.chu@...iatek.com>
Cc: Tomas Winkler <tomas.winkler@...el.com>
Link: https://lore.kernel.org/r/20191224220248.30138-5-bvanassche@acm.org
Reviewed-by: Alim Akhtar <alim.akhtar@...sung.com>
Signed-off-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/ufs/ufshcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index faf1959981784..b2cbdd01ab10b 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1910,12 +1910,12 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
 {
 	hba->lrb[task_tag].issue_time_stamp = ktime_get();
 	hba->lrb[task_tag].compl_time_stamp = ktime_set(0, 0);
+	ufshcd_add_command_trace(hba, task_tag, "send");
 	ufshcd_clk_scaling_start_busy(hba);
 	__set_bit(task_tag, &hba->outstanding_reqs);
 	ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	/* Make sure that doorbell is committed immediately */
 	wmb();
-	ufshcd_add_command_trace(hba, task_tag, "send");
 }
 
 /**
-- 
2.25.1