clk: atlas7: fix integer overflow in dto rate calculation (6132e89a) · Commits · 戴 / test

I cannot believe that I spend quite a lot time in finding this bug. It seems a pitfall people tend to fall in. In "int64 = int32 * int32", conversion from 32-bits to 64-bits comes after the multiplication. So this statement may not work as expected. Signed-off-by:

Yibo Cai <yibo.cai@csr.com> Signed-off-by:

Barry Song <Baohua.Song@csr.com> Signed-off-by:

Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/sirf/clk-atlas7.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -519,7 +519,7 @@ static unsigned long dto_clk_recalc_rate(struct clk_hw *hw,
		static long dto_clk_round_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long *parent_rate)
		{
		u64 dividend = rate * (1 << 29);
		u64 dividend = (u64)rate * (1 << 29);

		do_div(dividend, *parent_rate);
		dividend = parent_rate;
		@@ -531,7 +531,7 @@ static long dto_clk_round_rate(struct clk_hw *hw, unsigned long rate,
		static int dto_clk_set_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long parent_rate)
		{
		u64 dividend = rate * (1 << 29);
		u64 dividend = (u64)rate * (1 << 29);
		struct clk_dto *clk = to_dtoclk(hw);

		do_div(dividend, parent_rate);

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