In the current implementation the user may open a virtual tty which then
could fail to establish the underlying DLCI. The function gsmtty_open()
gets stuck in tty_port_block_til_ready() while waiting for a carrier rise.
This happens if the remote side fails to acknowledge the link establishment
request in time or completely. At some point gsm_dlci_close() is called
to abort the link establishment attempt. The function tries to inform the
associated virtual tty by performing a hangup. But the blocking loop within
tty_port_block_til_ready() is not informed about this event.
The patch proposed here fixes this by resetting the initialization state of
the virtual tty to ensure the loop exits and triggering it to make
tty_port_block_til_ready() return.
Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-7-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The function gsm_process_modem() exists to handle modem status bits of
incoming frames. This includes incoming MSC (modem status command) frames
and convergence layer type 2 data frames. The function, however, was only
designed to handle MSC frames as it expects the command length. Within
gsm_dlci_data() it is wrongly assumed that this is the same as the data
frame length. This is only true if the data frame contains only 1 byte of
payload.
This patch names the length parameter of gsm_process_modem() in a generic
manner to reflect its association. It also corrects all calls to the
function to handle the variable number of modem status octets correctly in
both cases.
Fixes: 7263287af9 ("tty: n_gsm: Fixed logic to decode break signal from modem status")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-6-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty flow control is handled via gsmtty_throttle() and gsmtty_unthrottle().
Both functions propagate the outgoing hardware flow control state to the
remote side via MSC (modem status command) frames. The local state is taken
from the RTS (ready to send) flag of the tty. However, RTS gets mapped to
DTR (data terminal ready), which is wrong.
This patch corrects this by mapping RTS to RTS.
Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-5-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The here fixed commit made the tty hangup asynchronous to avoid a circular
locking warning. I could not reproduce this warning. Furthermore, due to
the asynchronous hangup the function call now gets queued up while the
underlying tty is being freed. Depending on the timing this results in a
NULL pointer access in the global work queue scheduler. To be precise in
process_one_work(). Therefore, the previous commit made the issue worse
which it tried to fix.
This patch fixes this by falling back to the old behavior which uses a
blocking tty hangup call before freeing up the associated tty.
Fixes: 7030082a74 ("tty: n_gsm: avoid recursive locking with async port hangup")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-4-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Trying to open a DLCI by sending a SABM frame may fail with a timeout.
The link is closed on the initiator side without informing the responder
about this event. The responder assumes the link is open after sending a
UA frame to answer the SABM frame. The link gets stuck in a half open
state.
This patch fixes this by initiating the proper link termination procedure
after link setup timeout instead of silently closing it down.
Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-3-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 5.2.1.2 describes the encoding of the
C/R (command/response) bit. Table 1 shows that the actual encoding of the
C/R bit is inverted if the associated frame is sent by the responder.
The referenced commit fixed here further broke the internal meaning of this
bit in the outgoing path by always setting the C/R bit regardless of the
frame type.
This patch fixes both by setting the C/R bit always consistently for
command (1) and response (0) frames and inverting it later for the
responder where necessary. The meaning of this bit in the debug output
is being preserved and shows the bit as if it was encoded by the initiator.
This reflects only the frame type rather than the encoded combination of
communication side and frame type.
Fixes: cc0f42122a ("tty: n_gsm: Modify CR,PF bit when config requester")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-2-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 5.4.6.3.7 describes the encoding of the
control signal octet used by the MSC (modem status command). The same
encoding is also used in convergence layer type 2 as described in chapter
5.5.2. Table 7 and 24 both require the DV (data valid) bit to be set 1 for
outgoing control signal octets sent by the DTE (data terminal equipment),
i.e. for the initiator side.
Currently, the DV bit is only set if CD (carrier detect) is on, regardless
of the side.
This patch fixes this behavior by setting the DV bit on the initiator side
unconditionally.
Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 5.2.7.3 states that DC1 (XON) and DC3 (XOFF)
are the control characters defined in ISO/IEC 646. These shall be quoted if
seen in the data stream to avoid interpretation as flow control characters.
ISO/IEC 646 refers to the set of ISO standards described as the ISO
7-bit coded character set for information interchange. Its final version
is also known as ITU T.50.
See https://www.itu.int/rec/T-REC-T.50-199209-I/en
To abide the standard it is needed to quote DC1 and DC3 correctly if these
are seen as data bytes and not as control characters. The current
implementation already tries to enforce this but fails to catch all
defined cases. 3GPP 27.010 chapter 5.2.7.3 clearly states that the most
significant bit shall be ignored for DC1 and DC3 handling. The current
implementation handles only the case with the most significant bit set 0.
Cases in which DC1 and DC3 have the most significant bit set 1 are left
unhandled.
This patch fixes this by masking the data bytes with ISO_IEC_646_MASK (only
the 7 least significant bits set 1) before comparing them with XON
(a.k.a. DC1) and XOFF (a.k.a. DC3) when testing which byte values need
quotation via byte stuffing.
Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220120101857.2509-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As requester,because n_gsm has no uevent report for application,the
application can't know dlci connect or disconnect.
The application will control every dlcl dev by uevent,when application
receive gsmtty0 dev remove uevent,it will close mux function,and change to
normal mode.
Example:
Before modify:
gsmld receive DLC0 DISC,no event report to application
gsmld receive DLC1 SABM,no event report to application
gsmld receive DLC1 DISC,no event report to application
After modify:
Receive DLC0 DISC,report "/devices/virtual/tty/gsmtty0" remove uevent
Receive DLC1 SABM,report "/devices/virtual/tty/gsmtty1" add uevent
Receive DLC1 DISC,report "/devices/virtual/tty/gsmtty1" remove uevent
Signed-off-by: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>
Link: https://lore.kernel.org/r/1629461872-26965-7-git-send-email-zhenguo6858@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When n_gsm config "initiator=0",when gsmld config ,as requester ,it
doesn't need to send CLD frame data or SABM frame.
Example,when tty dev receive "AT+CMUX=0",it will change ldisc
n_tty to n_gsm,during config requester,gsmld output "7e 01 ef c3 aa 7e",
initiator maybe not want to receive the frame data.
[ 154.666457] c1 Q> 0) R: UIH(F)
[ 154.669514] c1 C3
[ 154.671519] c1 gsmld_output: 00000000: 7e 01 ef c3 aa 7e
[ 155.014874] c1 Q> 0) R: UIH(F)
[ 155.018000] c1 C3
[ 155.020046] c1 gsmld_output: 00000000: 7e 01 ef c3 aa 7e
[ 155.364425] c1 Q> 0) R: UIH(F)
[ 155.367546] c1 C3
[ 155.369597] c1 gsmld_output: 00000000: 7e 01 ef c3 aa 7e
Signed-off-by: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>
Link: https://lore.kernel.org/r/1629461872-26965-5-git-send-email-zhenguo6858@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes the following W=1 kernel build warning(s):
drivers/tty/n_gsm.c:525: warning: expecting prototype for gsm_stuff_packet(). Prototype was for gsm_stuff_frame() instead
drivers/tty/n_gsm.c:1608: warning: expecting prototype for gsm_dlci_control(). Prototype was for gsm_dlci_command() instead
drivers/tty/n_gsm.c:2561: warning: Function parameter or member 'cookie' not described in 'gsmld_read'
drivers/tty/n_gsm.c:2561: warning: Function parameter or member 'offset' not described in 'gsmld_read'
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210520121906.3468725-11-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
First, it is never checked. Second, use of it as a debugging aid is
at least questionable. With the current tools, I don't think anyone used
this kind of thing for debugging purposes for years.
On the top of that, e.g. serdev does not set this field of tty_ldisc_ops
at all.
So get rid of this legacy.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-8-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes both the "splice/sendfile to a tty" and "splice/sendfile from a
tty" regression from 5.10.
* 'tty-splice' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux:
tty: teach the n_tty ICANON case about the new "cookie continuations" too
tty: teach n_tty line discipline about the new "cookie continuations"
tty: clean up legacy leftovers from n_tty line discipline
tty: implement read_iter
tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer
tty: implement write_iter
The tty line discipline .read() function was passed the final user
pointer destination as an argument, which doesn't match the 'write()'
function, and makes it very inconvenient to do a splice method for
ttys.
This is a conversion to use a kernel buffer instead.
NOTE! It does this by passing the tty line discipline ->read() function
an additional "cookie" to fill in, and an offset into the cookie data.
The line discipline can fill in the cookie data with its own private
information, and then the reader will repeat the read until either the
cookie is cleared or it runs out of data.
The only real user of this is N_HDLC, which can use this to handle big
packets, even if the kernel buffer is smaller than the whole packet.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes the following W=1 kernel build warning(s):
drivers/tty/n_gsm.c:85: warning: Function parameter or member 'ref' not described in 'gsm_mux_net'
drivers/tty/n_gsm.c:85: warning: Function parameter or member 'dlci' not described in 'gsm_mux_net'
drivers/tty/n_gsm.c:664: warning: Function parameter or member 'dlci' not described in 'gsm_data_kick'
drivers/tty/n_gsm.c:1015: warning: Function parameter or member 'clen' not described in 'gsm_process_modem'
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-19-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
gsm->output and ->error are set only to gsmld_output and gsm_error,
respectively. Call these functions directly and remove error and output
function pointers from struct gsm_mux completely.
Note: we need a forward declaration of gsmld_output now.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200818085655.12071-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For at least some modems like the TELIT LE910, skipping SOF makes
transfers blocking indefinitely after a short amount of data
transferred.
Given the small improvement provided by skipping the SOF (just one
byte on about 100 bytes), it seems better to completely remove this
"feature" than make it optional.
Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Link: https://lore.kernel.org/r/20200512115323.1447922-3-gregory.clement@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
