cpufreq: schedutil: Fix rate limit overflow

rate_limit_us is an unsigned int, while NSEC_PER_USEC is defined as
1000L. On 32-bit systems, the multiplication is therefore performed
using 32-bit unsigned arithmetic before the result is assigned to
freq_update_delay_ns.

For example, writing 4294968 to rate_limit_us wraps the delay from
4294968000 ns to 704 ns. This makes schedutil update far more often
than configured.

Add sugov_update_rate_limit_us() to widen rate_limit_us to s64 before
converting it to nanoseconds. Use the helper when updating the tunable
through sysfs and when starting the governor, so both paths perform the
conversion without overflow.

Fixes: 9bdcb44e391d ("cpufreq: schedutil: New governor based on scheduler utilization data")
Signed-off-by: Hui Su <sh_def@163.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260806142304.1761454-1-sh_def@163.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions