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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Bean Huo <beanhuo@micron.com>,
        Avri Altman <avri.altman@wdc.com>,
        Jeffrey Hugo <jeffrey.l.hugo@gmail.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 078/136] scsi: ufs-qcom: Fix scheduling while atomic issue
Date:   Tue, 23 Jun 2020 21:58:54 +0200
Message-Id: <20200623195307.630309589@linuxfoundation.org>
In-Reply-To: <20200623195303.601828702@linuxfoundation.org>
References: <20200623195303.601828702@linuxfoundation.org>
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From: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>

[ Upstream commit 3be60b564de49875e47974c37fabced893cd0931 ]

ufs_qcom_dump_dbg_regs() uses usleep_range, a sleeping function, but can be
called from atomic context in the following flow:

ufshcd_intr -> ufshcd_sl_intr -> ufshcd_check_errors ->
ufshcd_print_host_regs -> ufshcd_vops_dbg_register_dump ->
ufs_qcom_dump_dbg_regs

This causes a boot crash on the Lenovo Miix 630 when the interrupt is
handled on the idle thread.

Fix the issue by switching to udelay().

Link: https://lore.kernel.org/r/20200525204125.46171-1-jeffrey.l.hugo@gmail.com
Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers")
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/ufs/ufs-qcom.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index f2b8de195d8af..ee3589ac64abf 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -1649,11 +1649,11 @@ static void ufs_qcom_dump_dbg_regs(struct ufs_hba *hba)
 
 	/* sleep a bit intermittently as we are dumping too much data */
 	ufs_qcom_print_hw_debug_reg_all(hba, NULL, ufs_qcom_dump_regs_wrapper);
-	usleep_range(1000, 1100);
+	udelay(1000);
 	ufs_qcom_testbus_read(hba);
-	usleep_range(1000, 1100);
+	udelay(1000);
 	ufs_qcom_print_unipro_testbus(hba);
-	usleep_range(1000, 1100);
+	udelay(1000);
 }
 
 /**
-- 
2.25.1