mmc: fix division by zero in MMC core

The card is not always clocked and the clock frequency zero is perfectly
legal, thus this code in mmc_set_data_timeout() may cause a division by
zero. It will be triggered more often if you're using software clock
gating but can be triggered under other conditions too.

Reported-by: Pierre Tardy <tardyp@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Reviewed-by: Chris Ball <cjb@laptop.org>
Cc: <stable@kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 4b1d8fb..6625c05 100644 (file)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -299,8 +299,9 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
                unsigned int timeout_us, limit_us;
 
                timeout_us = data->timeout_ns / 1000;
-               timeout_us += data->timeout_clks * 1000 /
-                       (mmc_host_clk_rate(card->host) / 1000);
+               if (mmc_host_clk_rate(card->host))
+                       timeout_us += data->timeout_clks * 1000 /
+                               (mmc_host_clk_rate(card->host) / 1000);
 
                if (data->flags & MMC_DATA_WRITE)
                        /*