| Message ID | 20201124093538.21177-4-ms@dev.tdt.de (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net/x25: netdev event handling | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 20 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
From: Martin Schiller > Sent: 24 November 2020 09:36 > > 1. DTE interface changes immediately to LAPB_STATE_1 and start sending > SABM(E). > > 2. DCE interface sends N2-times DM and changes to LAPB_STATE_1 > afterwards if there is no response in the meantime. Seems reasonable. It is 35 years since I wrote LAPB and I can't exactly remember what we did. If I stole a copy of the code it's on a QIC-150 tape cartridge! I really don't remember having a DTE/DCE option. It is likely that LAPB came up sending DM (response without F) until level3 requested the link come up when it would send N2 SABM+P hoping to get a UA+F. It would then send DM-F until a retry request was made. We certainly had several different types of crossover connectors for DTE-DTE working. David > > Signed-off-by: Martin Schiller <ms@dev.tdt.de> > --- > net/lapb/lapb_timer.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c > index 8f5b17001a07..baa247fe4ed0 100644 > --- a/net/lapb/lapb_timer.c > +++ b/net/lapb/lapb_timer.c > @@ -85,11 +85,18 @@ static void lapb_t1timer_expiry(struct timer_list *t) > switch (lapb->state) { > > /* > - * If we are a DCE, keep going DM .. DM .. DM > + * If we are a DCE, send DM up to N2 times, then switch to > + * STATE_1 and send SABM(E). > */ > case LAPB_STATE_0: > - if (lapb->mode & LAPB_DCE) > + if (lapb->mode & LAPB_DCE && > + lapb->n2count != lapb->n2) { > + lapb->n2count++; > lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); > + } else { > + lapb->state = LAPB_STATE_1; > + lapb_establish_data_link(lapb); > + } > break; > > /* > -- > 2.20.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On 2020-11-24 12:43, David Laight wrote: > From: Martin Schiller >> Sent: 24 November 2020 09:36 >> >> 1. DTE interface changes immediately to LAPB_STATE_1 and start sending >> SABM(E). >> >> 2. DCE interface sends N2-times DM and changes to LAPB_STATE_1 >> afterwards if there is no response in the meantime. > > Seems reasonable. > It is 35 years since I wrote LAPB and I can't exactly remember > what we did. > If I stole a copy of the code it's on a QIC-150 tape cartridge! > > I really don't remember having a DTE/DCE option. > It is likely that LAPB came up sending DM (response without F) > until level3 requested the link come up when it would send > N2 SABM+P hoping to get a UA+F. > It would then send DM-F until a retry request was made. > > We certainly had several different types of crossover connectors > for DTE-DTE working. > > David > The support for DTE/DCE was already in the LAPB code and I made it configurable from userspace (at least for hdlc interfaces) with this commit: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=f362e5fe0f1f For Layer3 (X.25) I will add it with an addional patch (you already commented on that) on a next step. The described behaviour above is my interpretation of point 2.4.4.1 of the "ITU-T Recommendation X.25 (10/96) aka "Blue Book" [1]. [1] https://www.itu.int/rec/T-REC-X.25-199610-I/ >> >> Signed-off-by: Martin Schiller <ms@dev.tdt.de> >> --- >> net/lapb/lapb_timer.c | 11 +++++++++-- >> 1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c >> index 8f5b17001a07..baa247fe4ed0 100644 >> --- a/net/lapb/lapb_timer.c >> +++ b/net/lapb/lapb_timer.c >> @@ -85,11 +85,18 @@ static void lapb_t1timer_expiry(struct timer_list >> *t) >> switch (lapb->state) { >> >> /* >> - * If we are a DCE, keep going DM .. DM .. DM >> + * If we are a DCE, send DM up to N2 times, then switch to >> + * STATE_1 and send SABM(E). >> */ >> case LAPB_STATE_0: >> - if (lapb->mode & LAPB_DCE) >> + if (lapb->mode & LAPB_DCE && >> + lapb->n2count != lapb->n2) { >> + lapb->n2count++; >> lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); >> + } else { >> + lapb->state = LAPB_STATE_1; >> + lapb_establish_data_link(lapb); >> + } >> break; >> >> /* >> -- >> 2.20.1 > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, > MK1 1PT, UK > Registration No: 1397386 (Wales)
diff --git a/net/lapb/lapb_timer.c b/net/lapb/lapb_timer.c index 8f5b17001a07..baa247fe4ed0 100644 --- a/net/lapb/lapb_timer.c +++ b/net/lapb/lapb_timer.c @@ -85,11 +85,18 @@ static void lapb_t1timer_expiry(struct timer_list *t) switch (lapb->state) { /* - * If we are a DCE, keep going DM .. DM .. DM + * If we are a DCE, send DM up to N2 times, then switch to + * STATE_1 and send SABM(E). */ case LAPB_STATE_0: - if (lapb->mode & LAPB_DCE) + if (lapb->mode & LAPB_DCE && + lapb->n2count != lapb->n2) { + lapb->n2count++; lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); + } else { + lapb->state = LAPB_STATE_1; + lapb_establish_data_link(lapb); + } break; /*
1. DTE interface changes immediately to LAPB_STATE_1 and start sending SABM(E). 2. DCE interface sends N2-times DM and changes to LAPB_STATE_1 afterwards if there is no response in the meantime. Signed-off-by: Martin Schiller <ms@dev.tdt.de> --- net/lapb/lapb_timer.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)