Re: [PATCH] dn_route: use time_is_before_jiffies(a) to replace "jiffies - a > 0"
From: Paolo Abeni <pabeni@redhat.com>
Date: 2022-07-28 13:11:19
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kernel-janitors, lkml
On Wed, 2022-07-27 at 10:46 +0800, Yu Zhe wrote:
quoted hunk ↗ jump to hunk
time_is_before_jiffies deals with timer wrapping correctly. Signed-off-by: Yu Zhe <redacted> --- net/decnet/dn_route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c index 552a53f1d5d0..0a4bed0bc2e3 100644 --- a/net/decnet/dn_route.c +++ b/net/decnet/dn_route.c@@ -201,7 +201,7 @@ static void dn_dst_check_expire(struct timer_list *unused) } spin_unlock(&dn_rt_hash_table[i].lock); - if ((jiffies - now) > 0) + if (time_is_before_jiffies(now))
Uhmm... it looks like the wrap-around condition can happen only in theory: 'now' is initialized just before entering this loop, and we will break as soon as jiffies increment. The wrap-around could happen only if a single iteration of the loop takes more than LONG_MAX jiffies. If that happens, we have a completely different kind of much more serious problem, I think ;) So this change is mostly for core readability's sake. I personally find more readable: if (jiffies != now) Cheers, Paolo p.s. given the above I guess this is for the net-next tree, right?