firmware: arm_scpi: Prevent the ternary sign expansion bug

How the type promotion works in ternary expressions is a bit tricky.
The problem is that scpi_clk_get_val() returns longs, "ret" is a int
which holds a negative error code, and le32_to_cpu() is an unsigned int.
We want the negative error code to be cast to a negative long.  But
because le32_to_cpu() is an u32 then "ret" is type promoted to u32 and
becomes a high positive and then it is promoted to long and it is still
a high positive value.

Fix this by getting rid of the ternary.

Link: https://lore.kernel.org/r/YIE7pdqV/h10tEAK@mwanda
Fixes: 8cb7cf56c9fe ("firmware: add support for ARM System Control and Power Interface(SCPI) protocol")
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[sudeep.holla: changed to return 0 as clock rate on error]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index d0dee37ad5228814e61142fe14dc9a992c6d2430..4ceba5ef789587f4e10ffb09dfa8c7892d7f82fe 100644 (file)
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -552,8 +552,10 @@ static unsigned long scpi_clk_get_val(u16 clk_id)
 
        ret = scpi_send_message(CMD_GET_CLOCK_VALUE, &le_clk_id,
                                sizeof(le_clk_id), &rate, sizeof(rate));
+       if (ret)
+               return 0;
 
-       return ret ? ret : le32_to_cpu(rate);
+       return le32_to_cpu(rate);
 }
 
 static int scpi_clk_set_val(u16 clk_id, unsigned long rate)