This is a note to let you know that I've just added the patch titled
tty: n_gsm: fix wrong T1 retry count handling
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-n_gsm-fix-wrong-t1-retry-count-handling.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3f91c5622455da9369f34449a150dfe7c47f2706
Author: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Date: Thu Jul 7 13:32:20 2022 +0200
tty: n_gsm: fix wrong T1 retry count handling
[ Upstream commit f30e10caa80aa1f35508bc17fc302dbbde9a833c ]
n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010.
See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516
The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to
the newer 27.010 here. Chapter 5.7.3 states that the valid range for the
maximum number of retransmissions (N2) is from 0 to 255 (both including).
gsm_dlci_t1() handles this number incorrectly by performing N2 - 1
retransmission attempts. Setting N2 to zero results in more than 255
retransmission attempts.
Fix gsm_dlci_t1() to comply with 3GPP 27.010.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220707113223.3685-1-daniel.starke@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 18878ab707af..5f5a7ad4c46a 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1546,8 +1546,8 @@ static void gsm_dlci_t1(unsigned long data)
switch (dlci->state) {
case DLCI_OPENING:
- dlci->retries--;
if (dlci->retries) {
+ dlci->retries--;
gsm_command(dlci->gsm, dlci->addr, SABM|PF);
mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
} else if (!dlci->addr && gsm->control == (DM | PF)) {
@@ -1562,8 +1562,8 @@ static void gsm_dlci_t1(unsigned long data)
break;
case DLCI_CLOSING:
- dlci->retries--;
if (dlci->retries) {
+ dlci->retries--;
gsm_command(dlci->gsm, dlci->addr, DISC|PF);
mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
} else
