blk-iocost: Fix an UBSAN shift-out-of-bounds warning

[platform/kernel/linux-starfive.git] / block / blk-iocost.c

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 089fcb9..7ee8d85 100644 (file)
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1353,6 +1353,13 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
 
        lockdep_assert_held(&iocg->waitq.lock);
 
+       /*
+        * If the delay is set by another CPU, we may be in the past. No need to
+        * change anything if so. This avoids decay calculation underflow.
+        */
+       if (time_before64(now->now, iocg->delay_at))
+               return false;
+
        /* calculate the current delay in effect - 1/2 every second */
        tdelta = now->now - iocg->delay_at;
        if (iocg->delay)