| Message ID | e72cc6c6ac5699659bb550fe04ec215ba393dd48.1684286522.git.lucien.xin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] sctp: fix an issue that plpmtu can never go to complete state | 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: 8 this patch: 8 |
| netdev/cc_maintainers | success | CCed 8 of 8 maintainers |
| netdev/build_clang | success | Errors and warnings before: 8 this patch: 8 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/deprecated_api | success | None detected |
| netdev/check_selftest | success | No net selftest shell script |
| netdev/verify_fixes | success | Fixes tag looks correct |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 8 this patch: 8 |
| netdev/checkpatch | warning | WARNING: line length of 84 exceeds 80 columns |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
On Tue, 2023-05-16 at 21:22 -0400, Xin Long wrote: > When doing plpmtu probe, the probe size is growing every time when it > receives the ACK during the Search state until the probe fails. When > the failure occurs, pl.probe_high is set and it goes to the Complete > state. > > However, if the link pmtu is huge, like 65535 in loopback_dev, the probe > eventually keeps using SCTP_MAX_PLPMTU as the probe size and never fails. > Because of that, pl.probe_high can not be set, and the plpmtu probe can > never go to the Complete state. > > Fix it by setting pl.probe_high to SCTP_MAX_PLPMTU when the probe size > grows to SCTP_MAX_PLPMTU in sctp_transport_pl_recv(). Also, increase > the probe size only when the next is less than SCTP_MAX_PLPMTU. > > Fixes: b87641aff9e7 ("sctp: do state transition when a probe succeeds on HB ACK recv path") > Signed-off-by: Xin Long <lucien.xin@gmail.com> > --- > net/sctp/transport.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/net/sctp/transport.c b/net/sctp/transport.c > index 2f66a2006517..b0ccfaa4c1d1 100644 > --- a/net/sctp/transport.c > +++ b/net/sctp/transport.c > @@ -324,9 +324,11 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) > t->pl.probe_size += SCTP_PL_BIG_STEP; > } else if (t->pl.state == SCTP_PL_SEARCH) { > if (!t->pl.probe_high) { > - t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, > - SCTP_MAX_PLPMTU); > - return false; > + if (t->pl.probe_size + SCTP_PL_BIG_STEP < SCTP_MAX_PLPMTU) { > + t->pl.probe_size += SCTP_PL_BIG_STEP; > + return false; > + } > + t->pl.probe_high = SCTP_MAX_PLPMTU; It looks like this way the probed mtu can't reach SCTP_MAX_PLPMTU anymore, while it was possible before. What about something alike: if (!t->pl.probe_high) { if (t->pl.probe_size < SCTP_MAX_PLPMTU) { t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, SCTP_MAX_PLPMTU); return false; } t->pl.probe_high = SCTP_MAX_PLPMTU; > } > t->pl.probe_size += SCTP_PL_MIN_STEP; > if (t->pl.probe_size >= t->pl.probe_high) { > @@ -341,7 +343,8 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) > } else if (t->pl.state == SCTP_PL_COMPLETE) { > /* Raise probe_size again after 30 * interval in Search Complete */ > t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */ > - t->pl.probe_size += SCTP_PL_MIN_STEP; > + if (t->pl.probe_size + SCTP_PL_MIN_STEP < SCTP_MAX_PLPMTU) > + t->pl.probe_size += SCTP_PL_MIN_STEP; In a similar way, should the above check be: if (t->pl.probe_size + SCTP_PL_MIN_STEP <= SCTP_MAX_PLPMTU) t->pl.probe_size += SCTP_PL_MIN_STEP; or simply: t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_MIN_STEP, SCTP_MAX_PLPMTU) > Cheers, Paolo
On Thu, May 18, 2023 at 6:18 AM Paolo Abeni <pabeni@redhat.com> wrote: > > On Tue, 2023-05-16 at 21:22 -0400, Xin Long wrote: > > When doing plpmtu probe, the probe size is growing every time when it > > receives the ACK during the Search state until the probe fails. When > > the failure occurs, pl.probe_high is set and it goes to the Complete > > state. > > > > However, if the link pmtu is huge, like 65535 in loopback_dev, the probe > > eventually keeps using SCTP_MAX_PLPMTU as the probe size and never fails. > > Because of that, pl.probe_high can not be set, and the plpmtu probe can > > never go to the Complete state. > > > > Fix it by setting pl.probe_high to SCTP_MAX_PLPMTU when the probe size > > grows to SCTP_MAX_PLPMTU in sctp_transport_pl_recv(). Also, increase > > the probe size only when the next is less than SCTP_MAX_PLPMTU. > > > > Fixes: b87641aff9e7 ("sctp: do state transition when a probe succeeds on HB ACK recv path") > > Signed-off-by: Xin Long <lucien.xin@gmail.com> > > --- > > net/sctp/transport.c | 11 +++++++---- > > 1 file changed, 7 insertions(+), 4 deletions(-) > > > > diff --git a/net/sctp/transport.c b/net/sctp/transport.c > > index 2f66a2006517..b0ccfaa4c1d1 100644 > > --- a/net/sctp/transport.c > > +++ b/net/sctp/transport.c > > @@ -324,9 +324,11 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) > > t->pl.probe_size += SCTP_PL_BIG_STEP; > > } else if (t->pl.state == SCTP_PL_SEARCH) { > > if (!t->pl.probe_high) { > > - t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, > > - SCTP_MAX_PLPMTU); > > - return false; > > + if (t->pl.probe_size + SCTP_PL_BIG_STEP < SCTP_MAX_PLPMTU) { > > + t->pl.probe_size += SCTP_PL_BIG_STEP; > > + return false; > > + } > > + t->pl.probe_high = SCTP_MAX_PLPMTU; > > It looks like this way the probed mtu can't reach SCTP_MAX_PLPMTU > anymore, while it was possible before. indeed. > > What about something alike: > > if (!t->pl.probe_high) { > if (t->pl.probe_size < SCTP_MAX_PLPMTU) { > t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, > SCTP_MAX_PLPMTU); > return false; > } > t->pl.probe_high = SCTP_MAX_PLPMTU; looks good. will post v2. Thanks. > > } > > t->pl.probe_size += SCTP_PL_MIN_STEP; > > if (t->pl.probe_size >= t->pl.probe_high) { > > @@ -341,7 +343,8 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) > > } else if (t->pl.state == SCTP_PL_COMPLETE) { > > /* Raise probe_size again after 30 * interval in Search Complete */ > > t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */ > > - t->pl.probe_size += SCTP_PL_MIN_STEP; > > + if (t->pl.probe_size + SCTP_PL_MIN_STEP < SCTP_MAX_PLPMTU) > > + t->pl.probe_size += SCTP_PL_MIN_STEP; > > In a similar way, should the above check be: > > if (t->pl.probe_size + SCTP_PL_MIN_STEP <= SCTP_MAX_PLPMTU) > t->pl.probe_size += SCTP_PL_MIN_STEP; > > or simply: > t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_MIN_STEP, SCTP_MAX_PLPMTU) > > > Cheers, > > Paolo >
diff --git a/net/sctp/transport.c b/net/sctp/transport.c index 2f66a2006517..b0ccfaa4c1d1 100644 --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -324,9 +324,11 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) t->pl.probe_size += SCTP_PL_BIG_STEP; } else if (t->pl.state == SCTP_PL_SEARCH) { if (!t->pl.probe_high) { - t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, - SCTP_MAX_PLPMTU); - return false; + if (t->pl.probe_size + SCTP_PL_BIG_STEP < SCTP_MAX_PLPMTU) { + t->pl.probe_size += SCTP_PL_BIG_STEP; + return false; + } + t->pl.probe_high = SCTP_MAX_PLPMTU; } t->pl.probe_size += SCTP_PL_MIN_STEP; if (t->pl.probe_size >= t->pl.probe_high) { @@ -341,7 +343,8 @@ bool sctp_transport_pl_recv(struct sctp_transport *t) } else if (t->pl.state == SCTP_PL_COMPLETE) { /* Raise probe_size again after 30 * interval in Search Complete */ t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */ - t->pl.probe_size += SCTP_PL_MIN_STEP; + if (t->pl.probe_size + SCTP_PL_MIN_STEP < SCTP_MAX_PLPMTU) + t->pl.probe_size += SCTP_PL_MIN_STEP; } return t->pl.state == SCTP_PL_COMPLETE;
When doing plpmtu probe, the probe size is growing every time when it receives the ACK during the Search state until the probe fails. When the failure occurs, pl.probe_high is set and it goes to the Complete state. However, if the link pmtu is huge, like 65535 in loopback_dev, the probe eventually keeps using SCTP_MAX_PLPMTU as the probe size and never fails. Because of that, pl.probe_high can not be set, and the plpmtu probe can never go to the Complete state. Fix it by setting pl.probe_high to SCTP_MAX_PLPMTU when the probe size grows to SCTP_MAX_PLPMTU in sctp_transport_pl_recv(). Also, increase the probe size only when the next is less than SCTP_MAX_PLPMTU. Fixes: b87641aff9e7 ("sctp: do state transition when a probe succeeds on HB ACK recv path") Signed-off-by: Xin Long <lucien.xin@gmail.com> --- net/sctp/transport.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)