| Message ID | 20230711000429.558248-1-pctammela@mojatatu.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net/sched: make psched_mtu() RTNL-less safe | expand |
| Context | Check | Description |
|---|---|---|
| netdev/series_format | success | Single patches do not need cover letters |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/fixes_present | success | Fixes tag present in non-next series |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 1408 this patch: 1408 |
| netdev/cc_maintainers | success | CCed 10 of 10 maintainers |
| netdev/build_clang | success | Errors and warnings before: 1368 this patch: 1368 |
| netdev/verify_signedoff | fail | author Signed-off-by missing |
| netdev/deprecated_api | success | None detected |
| netdev/check_selftest | success | No net selftest shell script |
| netdev/verify_fixes | success | No Fixes tag |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 1447 this patch: 1447 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
From: Pedro Tammela <pctammela@mojatatu.com> Date: Mon, 10 Jul 2023 21:04:29 -0300 > Eric Dumazet says[1]: > --- I think we shouldn't use `---` here, or the message below will be dropped while merging. > Speaking of psched_mtu(), I see that net/sched/sch_pie.c is using it > without holding RTNL, so dev->mtu can be changed underneath. > KCSAN could issue a warning. > --- > > Annotate dev->mtu with READ_ONCE() so KCSAN don't issue a warning. > > [1] https://lore.kernel.org/all/CANn89iJoJO5VtaJ-2=_d2aOQhb0Xw8iBT_Cxqp2HyuS-zj6azw@mail.gmail.com/ > > Fixes: d4b36210c2e6 ("net: pkt_sched: PIE AQM scheme") > Suggested-by: Eric Dumazet <edumazet@google.com> > Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> > --- > include/net/pkt_sched.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h > index e98aac9d5ad5..15960564e0c3 100644 > --- a/include/net/pkt_sched.h > +++ b/include/net/pkt_sched.h > @@ -134,7 +134,7 @@ extern const struct nla_policy rtm_tca_policy[TCA_MAX + 1]; > */ > static inline unsigned int psched_mtu(const struct net_device *dev) > { > - return dev->mtu + dev->hard_header_len; > + return READ_ONCE(dev->mtu) + dev->hard_header_len; > } > > static inline struct net *qdisc_net(struct Qdisc *q) > -- > 2.39.2
On 10/07/2023 21:14, Kuniyuki Iwashima wrote: > From: Pedro Tammela <pctammela@mojatatu.com> > Date: Mon, 10 Jul 2023 21:04:29 -0300 >> Eric Dumazet says[1]: >> --- > > I think we shouldn't use `---` here, or the message below will > be dropped while merging. Thanks for catching this. Will resend. > > >> Speaking of psched_mtu(), I see that net/sched/sch_pie.c is using it >> without holding RTNL, so dev->mtu can be changed underneath. >> KCSAN could issue a warning. >> --- >> >> Annotate dev->mtu with READ_ONCE() so KCSAN don't issue a warning. >> >> [1] https://lore.kernel.org/all/CANn89iJoJO5VtaJ-2=_d2aOQhb0Xw8iBT_Cxqp2HyuS-zj6azw@mail.gmail.com/ >> >> Fixes: d4b36210c2e6 ("net: pkt_sched: PIE AQM scheme") >> Suggested-by: Eric Dumazet <edumazet@google.com> >> Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> >> --- >> include/net/pkt_sched.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h >> index e98aac9d5ad5..15960564e0c3 100644 >> --- a/include/net/pkt_sched.h >> +++ b/include/net/pkt_sched.h >> @@ -134,7 +134,7 @@ extern const struct nla_policy rtm_tca_policy[TCA_MAX + 1]; >> */ >> static inline unsigned int psched_mtu(const struct net_device *dev) >> { >> - return dev->mtu + dev->hard_header_len; >> + return READ_ONCE(dev->mtu) + dev->hard_header_len; >> } >> >> static inline struct net *qdisc_net(struct Qdisc *q) >> -- >> 2.39.2
diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h index e98aac9d5ad5..15960564e0c3 100644 --- a/include/net/pkt_sched.h +++ b/include/net/pkt_sched.h @@ -134,7 +134,7 @@ extern const struct nla_policy rtm_tca_policy[TCA_MAX + 1]; */ static inline unsigned int psched_mtu(const struct net_device *dev) { - return dev->mtu + dev->hard_header_len; + return READ_ONCE(dev->mtu) + dev->hard_header_len; } static inline struct net *qdisc_net(struct Qdisc *q)
Eric Dumazet says[1]: --- Speaking of psched_mtu(), I see that net/sched/sch_pie.c is using it without holding RTNL, so dev->mtu can be changed underneath. KCSAN could issue a warning. --- Annotate dev->mtu with READ_ONCE() so KCSAN don't issue a warning. [1] https://lore.kernel.org/all/CANn89iJoJO5VtaJ-2=_d2aOQhb0Xw8iBT_Cxqp2HyuS-zj6azw@mail.gmail.com/ Fixes: d4b36210c2e6 ("net: pkt_sched: PIE AQM scheme") Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> --- include/net/pkt_sched.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)