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authorLars Poeschel <poeschel@lemonage.de>2014-01-07 13:34:37 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-22 12:41:27 -0800
commit5e33b2d90acb2d0272596cae533d920a0399a88a (patch)
treeb8d33239373db9ab4b65e042a09f6d2bed00720f
parent5de64260830aafce062b99e17cb3963ecc4291bf (diff)
downloadlinux-5e33b2d90acb2d0272596cae533d920a0399a88a.tar.gz
tty: n_gsm: Fix for modems with brk in modem status control
commit 3ac06b905655b3ef2fd2196bab36e4587e1e4e4f upstream. 3GPP TS 07.10 states in section 5.4.6.3.7: "The length byte contains the value 2 or 3 ... depending on the break signal." The break byte is optional and if it is sent, the length is 3. In fact the driver was not able to work with modems that send this break byte in their modem status control message. If the modem just sends the break byte if it is really set, then weird things might happen. The code for deconding the modem status to the internal linux presentation in gsm_process_modem has already a big comment about this 2 or 3 byte length thing and it is already able to decode the brk, but the code calling the gsm_process_modem function in gsm_control_modem does not encode it and hand it over the right way. This patch fixes this. Without this fix if the modem sends the brk byte in it's modem status control message the driver will hang when opening a muxed channel. Signed-off-by: Lars Poeschel <poeschel@lemonage.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/n_gsm.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 642239015b4..3ee7217e25b 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1089,6 +1089,7 @@ static void gsm_control_modem(struct gsm_mux *gsm, u8 *data, int clen)
{
unsigned int addr = 0;
unsigned int modem = 0;
+ unsigned int brk = 0;
struct gsm_dlci *dlci;
int len = clen;
u8 *dp = data;
@@ -1115,6 +1116,16 @@ static void gsm_control_modem(struct gsm_mux *gsm, u8 *data, int clen)
if (len == 0)
return;
}
+ len--;
+ if (len > 0) {
+ while (gsm_read_ea(&brk, *dp++) == 0) {
+ len--;
+ if (len == 0)
+ return;
+ }
+ modem <<= 7;
+ modem |= (brk & 0x7f);
+ }
tty = tty_port_tty_get(&dlci->port);
gsm_process_modem(tty, dlci, modem, clen);
if (tty) {