linux-kernel - [PATCH v4] mmc: dw_mmc: Fix the DTO/CTO timeout overflow calculation for 32-bit systems

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Message-Id: <20180228115318.20154-1-Evgeniy.Didin@synopsys.com>
Date:   Wed, 28 Feb 2018 14:53:18 +0300
From:   Evgeniy Didin <Evgeniy.Didin@...opsys.com>
To:     linux-mmc@...r.kernel.org
Cc:     Evgeniy Didin <Evgeniy.Didin@...opsys.com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Jisheng Zhang <Jisheng.Zhang@...aptics.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        stable@...r.kernel.org
Subject: [PATCH v4] mmc: dw_mmc: Fix the DTO/CTO timeout overflow calculation for 32-bit systems

In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") and
commit 4c2357f57dd5 ("mmc: dw_mmc: Fix the CTO timeout calculation") 
have been made changes which cause multiply overflow for 32-bit systems.
The broken timeout calculations leads to unexpected ETIMEDOUT errors and 
causes stacktrace splat (such as below) during normal data exchange 
with SD-card.

| Running :  4M-check-reassembly-tcp-cmykw2-rotatew2.out -v0 -w1
| -  Info: Finished target initialization.
| mmcblk0: error -110 transferring data, sector 320544, nr 2048, cmd response
|  0x900, card status 0x0

DIV_ROUND_UP_ULL helps to escape usage of __udivdi3() from libgcc and so
code gets compiled on all 32-bit platforms as opposed to usage
of DIV_ROUND_UP when we may only compile stuff on a very few arches.

Lets cast this multiply to u64 type which prevents overflow.

Tested-by: Vineet Gupta <Vineet.Gupta1@...opsys.com>
Reported-by: Vineet Gupta <Vineet.Gupta1@...opsys.com> # ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files
Fixes: 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation")
Fixes: 4c2357f57dd5 ("mmc: dw_mmc: Fix the CTO timeout calculation")

Signed-off-by: Evgeniy Didin <Evgeniy.Didin@...opsys.com>

CC: Alexey Brodkin <abrodkin@...opsys.com>
CC: Eugeniy Paltsev <paltsev@...opsys.com>
CC: Douglas Anderson <dianders@...omium.org>
CC: Ulf Hansson <ulf.hansson@...aro.org>
CC: Andy Shevchenko <andy.shevchenko@...il.com>
CC: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
CC: Shawn Lin <shawn.lin@...k-chips.com>
CC: Vineet Gupta <Vineet.Gupta1@...opsys.com>
CC: linux-kernel@...r.kernel.org
CC: linux-snps-arc@...ts.infradead.org
Cc: <stable@...r.kernel.org> 
---
Changes since v3:
-Switch DIV_ROUND_UP macro to DIV_ROUND_UP_ULL
-Make one patch from two patches
-Modify commit message

Changes sinve v2:
-add fix for cto_ms

Changes since v1:
-uint64_t switched to u64

 drivers/mmc/host/dw_mmc.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 0aa39975f33b..cba534d4c81b 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -409,7 +409,9 @@ static inline void dw_mci_set_cto(struct dw_mci *host)
 	cto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
 	if (cto_div == 0)
 		cto_div = 1;
-	cto_ms = DIV_ROUND_UP(MSEC_PER_SEC * cto_clks * cto_div, host->bus_hz);
+
+	cto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * cto_clks * cto_div,
+				  host->bus_hz);
 
 	/* add a bit spare time */
 	cto_ms += 10;
@@ -1944,8 +1946,9 @@ static void dw_mci_set_drto(struct dw_mci *host)
 	drto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
 	if (drto_div == 0)
 		drto_div = 1;
-	drto_ms = DIV_ROUND_UP(MSEC_PER_SEC * drto_clks * drto_div,
-			       host->bus_hz);
+
+	drto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * drto_clks * drto_div,
+				   host->bus_hz);
 
 	/* add a bit spare time */
 	drto_ms += 10;
-- 
2.11.0