On 9/6/20 9:43 PM, Simon Glass wrote:
Hi Sean,
On Tue, 1 Sep 2020 at 13:56, Sean Anderson seanga2@gmail.com wrote:
get_ticks does not always succeed. Sometimes it can be called before the timer has been initialized. If it does, it returns a negative errno. This causes the timer to appear non-monotonic, because the value will become much smaller after the timer is initialized.
No users of get_ticks which I checked handle errors of this kind. Further, functions like tick_to_time mangle the result of get_ticks, making it very unlikely that one could check for an error without suggesting a patch such as this one.
This patch changes get_ticks to always return 0 when there is an error. 0 is the least unsigned integer, ensuring get_ticks appears monotonic. This has the side effect of time apparently not passing until the timer is initialized. However, without this patch, time does not pass anyway, because the error value is likely to be the same.
Fixes: c8a7ba9e6a5 Signed-off-by: Sean Anderson seanga2@gmail.com
lib/time.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Would it be better to panic so people can fix the bug?
I thought this was expected behavior. It's only a bug if you do something like udelay before any timers are created. We just can't report errors through get_ticks, because its users assume that it always returns a time of some kind.
--Sean