linux-kernel - [PATCH v2] mmc: dw_mmc: Fix the DTO timeout overflow calculation for 32-bit systems

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Message-Id: <20180222133418.29336-1-Evgeniy.Didin@synopsys.com>
Date:   Thu, 22 Feb 2018 16:34:18 +0300
From:   Evgeniy Didin <Evgeniy.Didin@...opsys.com>
To:     linux-mmc@...r.kernel.org
Cc:     Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Douglas Anderson <dianders@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-kernel@...r.kernel.org, linux-snps-arc@...ts.infradead.org,
        stable@...r.kernel.org, Vineet Gupta <Vineet.Gupta1@...opsys.com>
Subject: [PATCH v2] mmc: dw_mmc: Fix the DTO timeout overflow calculation for 32-bit systems

In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") have been made
changes which cause multiply overflow for 32-bit systems.
The broken timeout calculations caused false interrupt latency warnings
and stacktrace splat (such as below) when accessing the 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
| mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 400000Hz, actual
| 396825HZ div = 63)
| mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 25000000Hz, actual
|  25000000HZ div = 1)
| ------------[ cut here ]------------
| softirq: huh, entered softirq 6 TASKLET 6f6a9412 with preempt_count 00000101,
| exited with 00000100?
| WARNING: CPU: 2 PID: 0 at ../lib/scatterlist.c:652 sg_miter_next+0x28/0x20c
| Modules linked in:
| CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.15.0 #57
|
| Stack Trace:
|  arc_unwind_core.constprop.1+0xd0/0xf4
|  dump_stack+0x68/0x80
|  warn_slowpath_null+0x4e/0xec
|  sg_miter_next+0x28/0x20c
|  dw_mci_read_data_pio+0x44/0x190
|  dw_mmc f000a000.mmc: Unexpected interrupt latency
|   dw_mci_interrupt+0x3ee/0x530
|  __handle_irq_event_percpu+0x56/0x150
|  handle_irq_event+0x34/0x78
|  handle_level_irq+0x8e/0x120
|  generic_handle_irq+0x1c/0x2c
|  idu_cascade_isr+0x30/0x6c
|  __handle_domain_irq+0x72/0xc8
|  ret_from_exception+0x0/0x8
|---[ end trace 2a58c9af6c25fe51 ]---

Lets cast this multiply to u64 type which prevents overflow.

Tested-by: Vineet Gupta <Vineet.Gupta1@...opsys.com>
Fixes: ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files

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: linux-kernel@...r.kernel.org
CC: linux-snps-arc@...ts.infradead.org
Cc: <stable@...r.kernel.org> #  9d9491a7da2a mmc: dw_mmc: Fix the DTO timeout calculation
---
Changes since v1:
-uint64_t switched to u64
-changed commit message
 drivers/mmc/host/dw_mmc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 0aa39975f33b..1a0b9751c67c 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1944,7 +1944,7 @@ 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,
+	drto_ms = DIV_ROUND_UP((u64)MSEC_PER_SEC * drto_clks * drto_div,
 			       host->bus_hz);
 
 	/* add a bit spare time */
-- 
2.11.0