| Message ID | 20220727024600.18413-1-yuzhe@nfschina.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | dn_route: use time_is_before_jiffies(a) to replace "jiffies - a > 0" | expand |
On Wed, 2022-07-27 at 10:46 +0800, Yu Zhe wrote: > time_is_before_jiffies deals with timer wrapping correctly. > > Signed-off-by: Yu Zhe <yuzhe@nfschina.com> > --- > 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?
在 2022年07月28日 21:11, Paolo Abeni 写道: > On Wed, 2022-07-27 at 10:46 +0800, Yu Zhe wrote: >> time_is_before_jiffies deals with timer wrapping correctly. >> >> Signed-off-by: Yu Zhe <yuzhe@nfschina.com> >> --- >> 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) I agree and I will send a v2 patch later. > > Cheers, > > Paolo > > p.s. given the above I guess this is for the net-next tree, right? > yes >
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)) break; }
time_is_before_jiffies deals with timer wrapping correctly. Signed-off-by: Yu Zhe <yuzhe@nfschina.com> --- net/decnet/dn_route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)