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* tty: make n_tty_read() always abort if hangup is in progressTejun Heo2018-02-281-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A tty is hung up by __tty_hangup() setting file->f_op to hung_up_tty_fops, which is skipped on ttys whose write operation isn't tty_write(). This means that, for example, /dev/console whose write op is redirected_tty_write() is never actually marked hung up. Because n_tty_read() uses the hung up status to decide whether to abort the waiting readers, the lack of hung-up marking can lead to the following scenario. 1. A session contains two processes. The leader and its child. The child ignores SIGHUP. 2. The leader exits and starts disassociating from the controlling terminal (/dev/console). 3. __tty_hangup() skips setting f_op to hung_up_tty_fops. 4. SIGHUP is delivered and ignored. 5. tty_ldisc_hangup() is invoked. It wakes up the waits which should clear the read lockers of tty->ldisc_sem. 6. The reader wakes up but because tty_hung_up_p() is false, it doesn't abort and goes back to sleep while read-holding tty->ldisc_sem. 7. The leader progresses to tty_ldisc_lock() in tty_ldisc_hangup() and is now stuck in D sleep indefinitely waiting for tty->ldisc_sem. The following is Alan's explanation on why some ttys aren't hung up. http://lkml.kernel.org/r/20171101170908.6ad08580@alans-desktop 1. It broke the serial consoles because they would hang up and close down the hardware. With tty_port that *should* be fixable properly for any cases remaining. 2. The console layer was (and still is) completely broken and doens't refcount properly. So if you turn on console hangups it breaks (as indeed does freeing consoles and half a dozen other things). As neither can be fixed quickly, this patch works around the problem by introducing a new flag, TTY_HUPPING, which is used solely to tell n_tty_read() that hang-up is in progress for the console and the readers should be aborted regardless of the hung-up status of the device. The following is a sample hung task warning caused by this issue. INFO: task agetty:2662 blocked for more than 120 seconds. Not tainted 4.11.3-dbg-tty-lockup-02478-gfd6c7ee-dirty #28 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 0 2662 1 0x00000086 Call Trace: __schedule+0x267/0x890 schedule+0x36/0x80 schedule_timeout+0x23c/0x2e0 ldsem_down_write+0xce/0x1f6 tty_ldisc_lock+0x16/0x30 tty_ldisc_hangup+0xb3/0x1b0 __tty_hangup+0x300/0x410 disassociate_ctty+0x6c/0x290 do_exit+0x7ef/0xb00 do_group_exit+0x3f/0xa0 get_signal+0x1b3/0x5d0 do_signal+0x28/0x660 exit_to_usermode_loop+0x46/0x86 do_syscall_64+0x9c/0xb0 entry_SYSCALL64_slow_path+0x25/0x25 The following is the repro. Run "$PROG /dev/console". The parent process hangs in D state. #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> #include <sys/ioctl.h> #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <signal.h> #include <time.h> #include <termios.h> int main(int argc, char **argv) { struct sigaction sact = { .sa_handler = SIG_IGN }; struct timespec ts1s = { .tv_sec = 1 }; pid_t pid; int fd; if (argc < 2) { fprintf(stderr, "test-hung-tty /dev/$TTY\n"); return 1; } /* fork a child to ensure that it isn't already the session leader */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { /* top parent, wait for everyone */ while (waitpid(-1, NULL, 0) >= 0) ; if (errno != ECHILD) perror("waitpid"); return 0; } /* new session, start a new session and set the controlling tty */ if (setsid() < 0) { perror("setsid"); return 1; } fd = open(argv[1], O_RDWR); if (fd < 0) { perror("open"); return 1; } if (ioctl(fd, TIOCSCTTY, 1) < 0) { perror("ioctl"); return 1; } /* fork a child, sleep a bit and exit */ pid = fork(); if (pid < 0) { perror("fork"); return 1; } if (pid > 0) { nanosleep(&ts1s, NULL); printf("Session leader exiting\n"); exit(0); } /* * The child ignores SIGHUP and keeps reading from the controlling * tty. Because SIGHUP is ignored, the child doesn't get killed on * parent exit and the bug in n_tty makes the read(2) block the * parent's control terminal hangup attempt. The parent ends up in * D sleep until the child is explicitly killed. */ sigaction(SIGHUP, &sact, NULL); printf("Child reading tty\n"); while (1) { char buf[1024]; if (read(fd, buf, sizeof(buf)) < 0) { perror("read"); return 1; } } return 0; } Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Cox <alan@llwyncelyn.cymru> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* vfs: do bulk POLL* -> EPOLL* replacementLinus Torvalds2018-02-111-7/+7
| | | | | | | | | | | | | | | | | | | | | | | This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'tty-4.16-rc1' of ↵Linus Torvalds2018-02-011-1/+9
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/staging driver updates from Greg KH: "Here is the big tty/serial driver update for 4.16-rc1. The usual number of various serial driver fixes and updates to try to get them to work with crazy hardware configurations (seriously, how many different ways are hardware engineers going to come up with to hook up a simple UART?) There is also some serdev bugfixes and updates, as well as a smattering of other small fixes in here. All have been in the linux-next tree for a while, with no reported issues" * tag 'tty-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (65 commits) tty: serial: exar: Relocate sleep wake-up handling tty: fix data race between tty_init_dev and flush of buf serial: imx: fix endless loop during suspend serial: core: mark port as initialized after successful IRQ change serdev: only match serdev devices serdev: do not generate modaliases for controllers serial: mxs-auart: don't use GPIOF_* with gpiod_get_direction serial: 8250_dw: Revert "Improve clock rate setting" MAINTAINERS: Add myself as designated reviewer for 8250_dw gpio: serial: max310x: Support open-drain configuration for GPIOs serdev: Fix serdev_uevent failure on ACPI enumerated serdev-controllers serial: 8250_ingenic: Parse earlycon options serial: 8250_ingenic: Add support for the JZ4770 SoC serial: core: Make uart_parse_options take const char* argument serial: 8250_of: fix return code when probe function fails to get reset serial: imx: Only wakeup via RTSDEN bit if the system has RTS/CTS serial: 8250_uniphier: fix error return code in uniphier_uart_probe() tty: n_gsm: Allow ADM response in addition to UA for control dlci tty: omap-serial: Fix initial on-boot RTS GPIO level tty: serial: jsm: Add one check against NULL pointer dereference ...
| * tty: fix data race between tty_init_dev and flush of bufGaurav Kohli2018-01-231-1/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There can be a race, if receive_buf call comes before tty initialization completes in n_tty_open and tty->disc_data may be NULL. CPU0 CPU1 ---- ---- 000|n_tty_receive_buf_common() n_tty_open() -001|n_tty_receive_buf2() tty_ldisc_open.isra.3() -002|tty_ldisc_receive_buf(inline) tty_ldisc_setup() Using ldisc semaphore lock in tty_init_dev till disc_data initializes completely. Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org> Reviewed-by: Alan Cox <alan@linux.intel.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * pty: cancel pty slave port buf's work in tty_releaseSahara2017-12-191-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In case that CONFIG_SLUB_DEBUG is on and pty is used, races between release_one_tty and flush_to_ldisc work threads may happen and lead to use-after-free condition on tty->link->port. Because SLUB_DEBUG is turned on, freed tty->link->port is filled with POISON_FREE value. So far without SLUB_DEBUG, port was filled with zero and flush_to_ldisc could return without a problem by checking if tty is NULL. CPU 0 CPU 1 ----- ----- release_tty pty_write cancel_work_sync(tty) to = tty->link tty_kref_put(tty->link) tty_schedule_flip(to->port) << workqueue >> ... release_one_tty ... pty_cleanup ... kfree(tty->link->port) << workqueue >> flush_to_ldisc tty = READ_ONCE(port->itty) tty is 0x6b6b6b6b6b6b6b6b !!PANIC!! access tty->ldisc Unable to handle kernel paging request at virtual address 6b6b6b6b6b6b6b93 pgd = ffffffc0eb1c3000 [6b6b6b6b6b6b6b93] *pgd=0000000000000000, *pud=0000000000000000 ------------[ cut here ]------------ Kernel BUG at ffffff800851154c [verbose debug info unavailable] Internal error: Oops - BUG: 96000004 [#1] PREEMPT SMP CPU: 3 PID: 265 Comm: kworker/u8:9 Tainted: G W 3.18.31-g0a58eeb #1 Hardware name: Qualcomm Technologies, Inc. MSM 8996pro v1.1 + PMI8996 Carbide (DT) Workqueue: events_unbound flush_to_ldisc task: ffffffc0ed610ec0 ti: ffffffc0ed624000 task.ti: ffffffc0ed624000 PC is at ldsem_down_read_trylock+0x0/0x4c LR is at tty_ldisc_ref+0x24/0x4c pc : [<ffffff800851154c>] lr : [<ffffff800850f6c0>] pstate: 80400145 sp : ffffffc0ed627cd0 x29: ffffffc0ed627cd0 x28: 0000000000000000 x27: ffffff8009e05000 x26: ffffffc0d382cfa0 x25: 0000000000000000 x24: ffffff800a012f08 x23: 0000000000000000 x22: ffffffc0703fbc88 x21: 6b6b6b6b6b6b6b6b x20: 6b6b6b6b6b6b6b93 x19: 0000000000000000 x18: 0000000000000001 x17: 00e80000f80d6f53 x16: 0000000000000001 x15: 0000007f7d826fff x14: 00000000000000a0 x13: 0000000000000000 x12: 0000000000000109 x11: 0000000000000000 x10: 0000000000000000 x9 : ffffffc0ed624000 x8 : ffffffc0ed611580 x7 : 0000000000000000 x6 : ffffff800a42e000 x5 : 00000000000003fc x4 : 0000000003bd1201 x3 : 0000000000000001 x2 : 0000000000000001 x1 : ffffff800851004c x0 : 6b6b6b6b6b6b6b93 Signed-off-by: Sahara <keun-o.park@darkmatter.ae> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | the rest of drivers/*: annotate ->poll() instancesAl Viro2017-11-281-3/+3
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | anntotate the places where ->poll() return values goAl Viro2017-11-271-1/+1
|/ | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* tty: add SPDX identifiers to all remaining files in drivers/tty/Greg Kroah-Hartman2017-11-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the drivers/tty files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Jiri Slaby <jslaby@suse.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: David Sterba <dsterba@suse.com> Cc: James Hogan <jhogan@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Eric Anholt <eric@anholt.net> Cc: Stefan Wahren <stefan.wahren@i2se.com> Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: Ray Jui <rjui@broadcom.com> Cc: Scott Branden <sbranden@broadcom.com> Cc: bcm-kernel-feedback-list@broadcom.com Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Joachim Eastwood <manabian@gmail.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Tobias Klauser <tklauser@distanz.ch> Cc: Russell King <linux@armlinux.org.uk> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Richard Genoud <richard.genoud@gmail.com> Cc: Alexander Shiyan <shc_work@mail.ru> Cc: Baruch Siach <baruch@tkos.co.il> Cc: "Maciej W. Rozycki" <macro@linux-mips.org> Cc: "Uwe Kleine-König" <kernel@pengutronix.de> Cc: Pat Gefre <pfg@sgi.com> Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Vladimir Zapolskiy <vz@mleia.com> Cc: Sylvain Lemieux <slemieux.tyco@gmail.com> Cc: Carlo Caione <carlo@caione.org> Cc: Kevin Hilman <khilman@baylibre.com> Cc: Liviu Dudau <liviu.dudau@arm.com> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Andy Gross <andy.gross@linaro.org> Cc: David Brown <david.brown@linaro.org> Cc: "Andreas Färber" <afaerber@suse.de> Cc: Kevin Cernekee <cernekee@gmail.com> Cc: Laxman Dewangan <ldewangan@nvidia.com> Cc: Thierry Reding <thierry.reding@gmail.com> Cc: Jonathan Hunter <jonathanh@nvidia.com> Cc: Barry Song <baohua@kernel.org> Cc: Patrice Chotard <patrice.chotard@st.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: Alexandre Torgue <alexandre.torgue@st.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Peter Korsgaard <jacmet@sunsite.dk> Cc: Timur Tabi <timur@tabi.org> Cc: Tony Prisk <linux@prisktech.co.nz> Cc: Michal Simek <michal.simek@xilinx.com> Cc: "Sören Brinkmann" <soren.brinkmann@xilinx.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Jiri Slaby <jslaby@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'staging-4.14-rc1' of ↵Linus Torvalds2017-09-051-7/+96
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging Pull staging/IIO driver updates from Greg KH: "Here is the big staging and IIO driver update for 4.14-rc1. Lots of staging driver fixes and cleanups, including some reorginizing of the lustre header files to try to impose some sanity on what is, and what is not, the uapi for that filesystem. There are some tty core changes in here as well, as the speakup drivers need them, and that's ok with me, they are sane and the speakup code is getting nicer because of it. There is also the addition of the obiligatory new wifi driver, just because it has been a release or two since we added our last one... Other than that, lots and lots of small coding style fixes, as usual. All of these have been in linux-next for a while with no reported issues" * tag 'staging-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (612 commits) staging:rtl8188eu:core Fix remove unneccessary else block staging: typec: fusb302: make structure fusb302_psy_desc static staging: unisys: visorbus: make two functions static staging: fsl-dpaa2/eth: fix off-by-one FD ctrl bitmaks staging: r8822be: Simplify deinit_priv() staging: r8822be: Remove some dead code staging: vboxvideo: Use CONFIG_DRM_KMS_FB_HELPER to check for fbdefio availability staging:rtl8188eu Fix comparison to NULL staging: rts5208: rename mmc_ddr_tunning_rx_cmd to mmc_ddr_tuning_rx_cmd Staging: Pi433: style fix - tabs and spaces staging: pi433: fix spelling mistake: "preample" -> "preamble" staging:rtl8188eu:core Fix Code Indent staging: typec: fusb302: Export current-limit through a power_supply class dev staging: typec: fusb302: Add support for USB2 charger detection through extcon staging: typec: fusb302: Use client->irq as irq if set staging: typec: fusb302: Get max snk mv/ma/mw from device-properties staging: typec: fusb302: Set max supply voltage to 5V staging: typec: tcpm: Add get_current_limit tcpc_dev callback staging:rtl8188eu Use __func__ instead of function name staging: lustre: coding style fixes found by checkpatch.pl ...
| * tty: undo export of tty_open_by_driverOkash Khawaja2017-08-281-2/+1
| | | | | | | | | | | | | | | | Since we have tty_kopen, we no longer need to export tty_open_by_driver. This patch makes this function static. Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * tty: resolve tty contention between kernel and user spaceOkash Khawaja2017-08-281-5/+95
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit 12e84c71b7d4 ("tty: export tty_open_by_driver") exports tty_open_by_device to allow tty to be opened from inside kernel which works fine except that it doesn't handle contention with user space or another kernel-space open of the same tty. For example, opening a tty from user space while it is kernel opened results in failure and a kernel log message about mismatch between tty->count and tty's file open count. This patch makes kernel access to tty exclusive, so that if a user process or kernel opens a kernel opened tty, it gets -EBUSY. It does this by adding TTY_KOPENED flag to tty->flags. When this flag is set, tty_open_by_driver returns -EBUSY. Instead of overloading tty_open_by_driver for both kernel and user space, this patch creates a separate function tty_kopen which closely follows tty_open_by_driver. tty_kclose closes the tty opened by tty_kopen. To address the mismatch between tty->count and #fd's, this patch adds #kopen's to the count before comparing it with tty->count. That way check_tty_count reflects correct usage count. Returning -EBUSY on tty open is a change in the interface. I have tested this with minicom, picocom and commands like "echo foo > /dev/ttyS0". They all correctly report "Device or resource busy" when the tty is already kernel opened. Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge tag 'tty-4.14-rc1' of ↵Linus Torvalds2017-09-051-0/+9
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial updates from Greg KH: "Here is the big tty/serial driver update for 4.14-rc1. Well, not all that big, just a number of small serial driver fixes, and a new serial driver. Also in here are some much needed goldfish tty driver (emulator) fixes to try to get that codebase under control. All of these have been in linux-next for a while with no reported issues" * tag 'tty-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (94 commits) tty: goldfish: Implement support for kernel 'earlycon' parameter tty: goldfish: Use streaming DMA for r/w operations on Ranchu platforms tty: goldfish: Refactor constants to better reflect their nature serial: 8250_port: Remove useless NULL checks earlycon: initialise baud field of earlycon device structure tty: hvcs: make ktermios const pty: show associative slave of ptmx in fdinfo tty: n_gsm: Add compat_ioctl tty: hvcs: constify vio_device_id tty: hvc_vio: constify vio_device_id tty: mips_ejtag_fdc: constify mips_cdmm_device_id Introduce 8250_men_mcb mcb: introduce mcb_get_resource() serial: imx: Avoid post-PIO cleanup if TX DMA is started tty: serial: imx: disable irq after suspend serial: 8250_uniphier: add suspend/resume support serial: 8250_uniphier: use CHAR register for canary to detect power-off serial: 8250_uniphier: fix serial port index in private data serial: 8250: of: Add new port type for MediaTek BTIF controller on MT7622/23 SoC dt-bindings: serial: 8250: Add MediaTek BTIF controller bindings ...
| * pty: show associative slave of ptmx in fdinfoMasatake YAMATO2017-08-281-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds "tty-index" field to /proc/PID/fdinfo/N if N specifies /dev/ptmx. The field shows the index of associative slave pts. Though a minor number is given for each pts instance, ptmx is not. It means there is no way in user-space to know the association between file descriptors for pts/n and ptmx. (n = 0, 1, ...) This is different from pipe. About pipe such association can be solved by inode of pipefs. Providing the way to know the association between pts/n and ptmx helps users understand the status of running system. lsof can utilize this field. Signed-off-by: Masatake YAMATO <yamato@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | pty: Repair TIOCGPTPEEREric W. Biederman2017-08-241-0/+3
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The implementation of TIOCGPTPEER has two issues. When /dev/ptmx (as opposed to /dev/pts/ptmx) is opened the wrong vfsmount is passed to dentry_open. Which results in the kernel displaying the wrong pathname for the peer. The second is simply by caching the vfsmount and dentry of the peer it leaves them open, in a way they were not previously Which because of the inreased reference counts can cause unnecessary behaviour differences resulting in regressions. To fix these move the ioctl into tty_io.c at a generic level allowing the ioctl to have access to the struct file on which the ioctl is being called. This allows the path of the slave to be derived when opening the slave through TIOCGPTPEER instead of requiring the path to the slave be cached. Thus removing the need for caching the path. A new function devpts_ptmx_path is factored out of devpts_acquire and used to implement a function devpts_mntget. The new function devpts_mntget takes a filp to perform the lookup on and fsi so that it can confirm that the superblock that is found by devpts_ptmx_path is the proper superblock. v2: Lots of fixes to make the code actually work v3: Suggestions by Linus - Removed the unnecessary initialization of filp in ptm_open_peer - Simplified devpts_ptmx_path as gotos are no longer required [ This is the fix for the issue that was reverted in commit 143c97cc6529, but this time without breaking 'pbuilder' due to increased reference counts - Linus ] Fixes: 54ebbfb16034 ("tty: add TIOCGPTPEER ioctl") Reported-by: Christian Brauner <christian.brauner@canonical.com> Reported-and-tested-by: Stefan Lippers-Hollmann <s.l-h@gmx.de> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: add function to convert device name to numberOkash Khawaja2017-06-271-0/+50
| | | | | | | | | | The function converts strings like ttyS0 and ttyUSB0 to dev_t like (4, 64) and (188, 0). It does this by scanning tty_drivers list for corresponding device name and index. If the driver is not registered, this function returns -ENODEV. It also acquires tty_mutex. Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: export tty_open_by_driverOkash Khawaja2017-05-161-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This exports tty_open_by_driver so that it can be called from other places inside the kernel. The checks for null file pointer are based on Alan Cox's patch here: http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1215095.html. Description below is quoted from it: "[RFC] tty_port: allow a port to be opened with a tty that has no file handle Let us create tty objects entirely in kernel space. Untested proposal to show why all the ideas around rewriting half the uart stack are not needed. With this a kernel created non file backed tty object could be used to handle data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in particular has to work back to the fs/tty layer. The tty_port code is however otherwise clean of file handles as far as I can tell as is the low level tty port write path used by the ldisc, the configuration low level interfaces and most of the ldiscs. Currently you don't have any exposure to see tty hangups because those are built around the file layer. However a) it's a fixed port so you probably don't care about that b) if you do we can add a callback and c) you almost certainly don't want the userspace tear down/rebuild behaviour anyway. This should however be sufficient if we wanted for example to enumerate all the bluetooth bound fixed ports via ACPI and make them directly available. It doesn't deal with the case of a user opening a port that's also kernel opened and that would need some locking out (so it returned EBUSY if bound to a kernel device of some kind). That needs resolving along with how you "up" or "down" your new bluetooth device, or enumerate it while providing the existing tty API to avoid regressions (and to debug)." The exported funtion is used later in this patch set to gain access to tty_struct. [changed export symbol level - gkh] Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: split job control support into a file of its ownNicolas Pitre2017-04-181-536/+11
| | | | | | | | | This makes it easier for job control to become optional and/or usable independently from tty_io.c, as well as providing a nice purpose separation. No logical changes from this patch. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* console: move console_init() out of tty_io.cNicolas Pitre2017-04-181-24/+0
| | | | | | | | | All the console driver handling code lives in printk.c. Move console_init() there as well so console support can still be used when the TTY code is configured out. No logical changes from this patch. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: fix comment typo s/repsonsible/responsible/Thadeu Lima de Souza Cascardo2017-04-081-1/+1
| | | | | Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@cascardo.eti.br> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: reset termios state on device registrationJohan Hovold2017-03-311-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | Free any saved termios data when registering a tty device so that the termios state is reset when reusing a minor number. This is useful for hot-pluggable buses such as USB where it does not make much sense to reuse saved termios data from an unrelated device when a new device is later plugged in. This specifically avoids a situation where the new device does not have the carrier-detect signal wired, but the saved termios state has CLOCAL cleared, effectively preventing the port from being opened in blocking mode as noted by Jan Kundrát <jan.kundrat@cesnet.cz>. Note that clearing the saved data at deregistration would not work as the device could still be open. Also note that the termios data is not reset for drivers with TTY_DRIVER_DYNAMIC_ALLOC set (e.g. legacy pty) as their character device is registered at driver registration and could theoretically already have been opened (and pty termios state is never saved anyway). Reported-by: Jan Kundrát <jan.kundrat@cesnet.cz> Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: drop obsolete termios_locked commentsJohan Hovold2017-03-311-6/+1
| | | | | | | | | Drop comments about tty-driver termios_locked structures, which have been outdated since commit fe6e29fdb1a7 ("tty: simplify ktermios allocation"). Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: close race between device register and openJohan Hovold2017-03-311-20/+20
| | | | | | | | | | | | | | | | | | | The tty class device is currently not registered until after the character device has been registered thereby leaving a small window were a racing open could end up with a NULL tty->dev pointer due to the class-device lookup failing in alloc_tty_struct. Close this race by registering the class device before the character device while making sure to defer the user-space uevent notification until after the character device has been registered. Note that some tty drivers expect a valid tty->dev and would misbehave or crash otherwise. Some line disciplines also currently dereference the class device unconditionally despite the fact that not every tty is guaranteed to have one (Unix98 pty), but this is being fixed separately. Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* drivers/tty: Convert remaining uses of pr_warning to pr_warnJoe Perches2017-03-171-2/+2
| | | | | | | | | | | | To enable eventual removal of pr_warning This makes pr_warn use consistent for drivers/tty Prior to this patch, there were 2 uses of pr_warning and 23 uses of pr_warn in drivers/tty Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-0/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/task.h> We are going to split <linux/sched/task.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/task.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar2017-03-021-1/+1
| | | | | | | | | | | | | | | | | | | | <linux/sched/signal.h> We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/signal.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* tty_port: allow a port to be opened with a tty that has no file handleAlan Cox2017-01-191-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Let us create tty objects entirely in kernel space. Untested proposal to show why all the ideas around rewriting half the uart stack are not needed. With this a kernel created non file backed tty object could be used to handle data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in particular has to work back to the fs/tty layer. The tty_port code is however otherwise clean of file handles as far as I can tell as is the low level tty port write path used by the ldisc, the configuration low level interfaces and most of the ldiscs. Currently you don't have any exposure to see tty hangups because those are built around the file layer. However a) it's a fixed port so you probably don't care about that b) if you do we can add a callback and c) you almost certainly don't want the userspace tear down/rebuild behaviour anyway. This should however be sufficient if we wanted for example to enumerate all the bluetooth bound fixed ports via ACPI and make them directly available. It doesn't deal with the case of a user opening a port that's also kernel opened and that would need some locking out (so it returned EBUSY if bound to a kernel device of some kind). That needs resolving along with how you "up" or "down" your new bluetooth device, or enumerate it while providing the existing tty API to avoid regressions (and to debug). Signed-off-by: Alan Cox <alan@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-By: Sebastian Reichel <sre@kernel.org> Signed-off-by: Rob Herring <robh@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: move the non-file related parts of tty_release to new tty_release_structRob Herring2017-01-191-18/+32
| | | | | | | | | | | | | For in-kernel tty users, we need to be able to create and destroy 'struct tty' that are not associated with a file. The creation side is fine, but tty_release() needs to be split into the file handle portion and the struct tty portion. Introduce a new function, tty_release_struct, to handle just the destroying of a struct tty. Signed-off-by: Rob Herring <robh@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-By: Sebastian Reichel <sre@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge 4.6-rc7 into tty-nextGreg Kroah-Hartman2016-05-091-3/+3
|\ | | | | | | | | | | We want the pty fixes in here as well so that patches can build on it. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * devpts: more pty driver interface cleanupsLinus Torvalds2016-04-261-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is more prep-work for the upcoming pty changes. Still just code cleanup with no actual semantic changes. This removes a bunch pointless complexity by just having the slave pty side remember the dentry associated with the devpts slave rather than the inode. That allows us to remove all the "look up the dentry" code for when we want to remove it again. Together with moving the tty pointer from "inode->i_private" to "dentry->d_fsdata" and getting rid of pointless inode locking, this removes about 30 lines of code. Not only is the end result smaller, it's simpler and easier to understand. The old code, for example, depended on the d_find_alias() to not just find the dentry, but also to check that it is still hashed, which in turn validated the tty pointer in the inode. That is a _very_ roundabout way to say "invalidate the cached tty pointer when the dentry is removed". The new code just does dentry->d_fsdata = NULL; in devpts_pty_kill() instead, invalidating the tty pointer rather more directly and obviously. Don't do something complex and subtle when the obvious straightforward approach will do. The rest of the patch (ie apart from code deletion and the above tty pointer clearing) is just switching the calling convention to pass the dentry or file pointer around instead of the inode. Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: Willy Tarreau <w@1wt.eu> Cc: Aurelien Jarno <aurelien@aurel32.net> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jann Horn <jann@thejh.net> Cc: Greg KH <greg@kroah.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | tty: Remove stale parameter commentPeter Hurley2016-04-301-1/+0
| | | | | | | | | | | | | | | | noctty was removed as a parameter by commit 11e1d4aa4da ("tty: Consolidate noctty check in tty_open()"). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Remove unused TTY_NUMBER() macroPeter Hurley2016-04-301-3/+0
| | | | | | | | | | | | | | | | TTY_NUMBER() has been unused since v2.5.71; removed by "[PATCH] callout removal: callout is gone". Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | tty: Replace TTY_IO_ERROR bit tests with tty_io_error()Peter Hurley2016-04-301-3/+2
|/ | | | | | | | | Abstract TTY_IO_ERROR status test treewide with tty_io_error(). NB: tty->flags uses atomic bit ops; replace non-atomic bit test with test_bit(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix merge of "tty: Refactor tty_open()"Peter Hurley2016-03-311-2/+1
| | | | | | | | | | | | | Commit e9036d066236 ("tty: Drop krefs for interrupted tty lock") fixed a tty reference counting problem introduced in commit 0bfd464d3fdd ("tty: Wait interruptibly for tty lock on reopen"), so v4.5.0 is correct. However, commit d6203d0c7b73 ("tty: Refactor tty_open()") moved the relevant code for 4.6-rc1; correct the merge. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix UML console breakagePeter Hurley2016-03-311-1/+1
| | | | | | | | | | | User-Mode Linux supplies an alternate TTY_MAJOR driver for stdio console, so the noctty check in tty_open() must apply only to VT driver tty0 devnode and not the UML console driver tty0 devnode. Fixes: 11e1d4aa4da1 ("tty: Consolidate noctty checks in tty_open()") Reported-by: Richard Weinberger <richard.weinberger@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix ioctl(FIOASYNC) on hungup filePeter Hurley2016-01-281-2/+3
| | | | | | | | | | | | | | | | | | | | | | | A small race window exists which allows signal-driven async i/o to be enabled for the tty when the file ptr has already been hungup and signal-driven i/o has been disabled: CPU 0 CPU 1 ----- ------ ioctl_fioasync(on) filp->f_op->fasync(on) __tty_hangup() tty_fasync(on) tty_lock() tty_lock() ... . filp->f_op = &hung_up_tty_fops; (waiting) __tty_fasync(off) . tty_unlock() /* gets tty lock */ /* enables FASYNC */ Check the tty has not been hungup while holding tty_lock. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Add fasync() hung up file operationPeter Hurley2016-01-281-0/+6
| | | | | | | | | | | | | VFS uses a two-stage check-and-call method for invoking file_operations methods, without explicitly snapshotting either the file_operations ptr or the function ptr. Since the tty core is one of the few VFS users that changes the f_op file_operations ptr of the file descriptor (when the tty has been hung up), and since the likelihood of the compiler generating a reload of either f_op or the function ptr is basically nil, just define a hung up fasync() file operation that returns an error. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty, n_tty: Remove fasync() ldisc notificationPeter Hurley2016-01-281-8/+0
| | | | | | | | | | | | | | | | | | | | | | | Only the N_TTY line discipline implements the signal-driven i/o notification enabled/disabled by fcntl(F_SETFL, O_ASYNC). The ldisc fasync() notification is sent to the ldisc when the enable state has changed (the tty core is notified via the fasync() VFS file operation). The N_TTY line discipline used the enable state to change the wakeup condition (minimum_to_wake = 1) for notifying the signal handler i/o is available. However, just the presence of data is sufficient and necessary to signal i/o is available, so changing minimum_to_wake is unnecessary (and creates a race condition with read() and poll() which may be concurrently updating minimum_to_wake). Furthermore, since the kill_fasync() VFS helper performs no action if the fasync list is empty, calling unconditionally is preferred; if signal driven i/o just has been disabled, no signal will be sent by kill_fasync() anyway so notification of the change via the ldisc fasync() method is superfluous. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Make tty_files_lock per-ttyPeter Hurley2016-01-271-13/+12
| | | | | | | | | | Access to tty->tty_files list is always per-tty, never for all ttys simultaneously. Replace global tty_files_lock spinlock with per-tty ->files_lock. Initialize when the ->tty_files list is inited, in alloc_tty_struct(). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Move tty_check_change() helperPeter Hurley2016-01-271-0/+6
| | | | | | | | Move is_ignored() to drivers/tty/tty_io.c and re-declare in file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Eliminate global symbol tty_ldisc_N_TTYPeter Hurley2016-01-271-1/+1
| | | | | | | | Reduce global tty symbols; move and rename tty_ldisc_begin() as n_tty_init() and redefine the N_TTY ldisc ops as file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Unexport system-wide tty_mutexPeter Hurley2016-01-271-3/+1
| | | | | | | | tty_mutex is a core, system-wide lock; there is no reason for any code outside the tty core to have direct access. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Document c_line == N_TTY initial conditionPeter Hurley2016-01-271-1/+2
| | | | | | | | The line discipline id is stored in the tty's termios; document the implicit initial value of N_TTY. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Destroy ldisc instance on hangupPeter Hurley2016-01-271-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, when the tty is hungup, the ldisc is re-instanced; ie., the current instance is destroyed and a new instance is created. The purpose of this design was to guarantee a valid, open ldisc for the lifetime of the tty. However, now that tty buffers are owned by and have lifetime equivalent to the tty_port (since v3.10), any data received immediately after the ldisc is re-instanced may cause continued driver i/o operations concurrently with the driver's hangup() operation. For drivers that shutdown h/w on hangup, this is unexpected and usually bad. For example, the serial core may free the xmit buffer page concurrently with an in-progress write() operation (triggered by echo). With the existing stable and robust ldisc reference handling, the cleaned-up tty_reopen(), the straggling unsafe ldisc use cleaned up, and the preparation to properly handle a NULL tty->ldisc, the ldisc instance can be destroyed and only re-instanced when the tty is re-opened. If the tty was opened as /dev/console or /dev/tty0, the original behavior of re-instancing the ldisc is retained (the 'reinit' parameter to tty_ldisc_hangup() is true). This is required since those file descriptors are never hungup. This patch has neglible impact on userspace; the tty file_operations ptr is changed to point to the hungup file operations _before_ the ldisc instance is destroyed, so only racing file operations might now retrieve a NULL ldisc reference (which is simply handled as if the hungup file operation had been called instead -- see "tty: Prepare for destroying line discipline on hangup"). This resolves a long-standing FIXME and several crash reports. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Use 'disc' for line discipline index namePeter Hurley2016-01-271-3/+3
| | | | | | | | | | tty->ldisc is a ptr to struct tty_ldisc, but unfortunately 'ldisc' is also used as a parameter or local name to refer to the line discipline index value (ie, N_TTY, N_GSM, etc.); instead prefer the name used by the line discipline registration/ref counting functions. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Prepare for destroying line discipline on hangupPeter Hurley2016-01-271-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tty file_operations (read/write/ioctl) wait for the ldisc reference indefinitely (until ldisc lifetime events, such as hangup or TIOCSETD, finish). Since hangup now destroys the ldisc and does not instance another copy, file_operations must now be prepared to receive a NULL ldisc reference from tty_ldisc_ref_wait(): CPU 0 CPU 1 ----- ----- (*f_op->read)() => tty_read() __tty_hangup() ... f_op = &hung_up_tty_fops; ... tty_ldisc_hangup() tty_ldisc_lock() tty_ldisc_kill() tty->ldisc = NULL tty_ldisc_unlock() ld = tty_ldisc_ref_wait() /* ld == NULL */ Instead, the action taken now is to return the same value as if the tty had been hungup a moment earlier: CPU 0 CPU 1 ----- ----- __tty_hangup() ... f_op = &hung_up_tty_fops; (*f_op->read)() => hung_up_tty_read() return 0; ... tty_ldisc_hangup() tty_ldisc_lock() tty_ldisc_kill() tty->ldisc = NULL tty_ldisc_unlock() Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Reset c_line from driver's init_termiosPeter Hurley2016-01-271-2/+3
| | | | | | | | | | | | | After the ldisc is released, but before the tty is destroyed, the termios is saved (in tty_free_termios()); this termios is restored if a new tty is created on next open(). However, the line discipline is always reset, which is not obvious in the current method. Instead, reset as part of the restore. Restore the original line discipline, which may not have been N_TTY. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Refactor tty_open()Peter Hurley2016-01-271-53/+67
| | | | | | | | Extract the driver lookup and reopen-or-initialize logic into helper function tty_open_by_driver(). No functional change. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Consolidate noctty checks in tty_open()Peter Hurley2016-01-271-9/+8
| | | | | | | | Evaluate the conditions which prevent this tty being the controlling terminal in one place, just before setting the controlling terminal. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Re-declare tty_driver_remove_tty() file scopePeter Hurley2016-01-271-1/+1
| | | | | | | tty_driver_remove_tty() is only local-scope; declare as static. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tty: Fix tty_init_termios() declarationPeter Hurley2016-01-271-9/+4
| | | | | | | | | | | tty_init_termios() never returns an error; re-declare as void. Remove unnecessary error handling from callers. Remove extern declarations of tty_free_termios() and free_tty_struct() and re-declare in file scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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