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path: root/drivers/tty/tty_io.c
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2015-12-13tty: core: Prefer dev_dbg() over pr_debug()Peter Hurley1-1/+1
Where possible, use dev_dbg() instead of pr_debug() Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: Remove __func__ from tty_debug() macroPeter Hurley1-7/+7
Now that tty_debug() macro uses pr_debug(), the function name can be printed when using dynamic debug; printing the function name within the format string is redundant. Remove the __func__ parameter and print specifier from the format string. Add context to messages for when the function name is not printed by dynamic debug, or when dynamic debug is not enabled. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: core: Prefer pr_* to printk(*)Peter Hurley1-4/+2
Convert remaining printk() use to pr_*() when tty is unknown or unsafe to use. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: core: Add driver name to invalid device registration messagePeter Hurley1-2/+2
Include the driver name in the tty_register_device_attr() error message for invalid index. Note that tty_err() cannot be used here because there is no tty; use pr_err(). Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: Convert SAK messages to tty_notice()Peter Hurley1-12/+8
Use tty_notice() for unified message format from the tty core. Fix each message to accurately reflect the cause of each termination. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: Define tty_*() printk macrosPeter Hurley1-17/+10
Since not all ttys are devices (eg., SysV ptys), dev_*() printk macros cannot be used. Define tty_*() printk macros that output in similar format to dev_*() macros (ie., <driver> <tty>: .....). Transform the most-trivial printk( LEVEL ...) usage to tty_*() usage. NB: The function name has been eliminated from messages with unique context, or prefixed to the format when given. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: core: Add helper fn to deref tty driver namePeter Hurley1-0/+7
Similar to tty_name(), add tty_driver_name() helper to safely dereference tty->driver->name (otherwise return empty string). Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: core: Remove redundant oom messagePeter Hurley1-3/+1
kmalloc() already emits a diagnostic for failed allocations; remove tty-specific message. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-12-13tty: Make tty_paranoia_check() file scopePeter Hurley1-1/+1
tty_paranoia_check() is only used within drivers/tty/tty_io.c; remove extern declaration in header and limit symbol to file scope. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-11-20tty: Fix tty_send_xchar() lock order inversionPeter Hurley1-0/+4
The correct lock order is atomic_write_lock => termios_rwsem, as established by tty_write() => n_tty_write(). Fixes: c274f6ef1c666 ("tty: Hold termios_rwsem for tcflow(TCIxxx)") Reported-and-Tested-by: Dmitry Vyukov <[email protected]> Cc: <[email protected]> # v3.18+ Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-10-17tty: Abstract tty buffer workPeter Hurley1-1/+1
Introduce API functions to restart and cancel tty buffer work, rather than manipulate buffer work directly. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-10-17tty: Prevent tty teardown during tty_write_message()Peter Hurley1-4/+2
tty_write_message() allows the caller to directly write to a specific tty. Since the line discipline is bypassed for the direct write, nothing prevents the tty from being torn down after the tty count is checked. Hold the tty lock for the duration of the direct write. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-10-17tty: core: Use correct spinlock flavor in tiocspgrp()Peter Hurley1-3/+2
tiocspgrp() is the ioctl handler for TIOCSPGRP, which runs in non-atomic context; use spin_lock/unlock_irq (since interrupt state is on). Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-10-17tty: Combine SIGTTOU/SIGTTIN handlingPeter Hurley1-22/+24
The job_control() check in n_tty_read() has nearly identical purpose and results as tty_check_change(). Both functions' purpose is to determine if the current task's pgrp is the foreground pgrp for the tty, and if not, to signal the current pgrp. Introduce __tty_check_change() which takes the signal to send and performs the shared operations for job control() and tty_check_change(). Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-10-04drivers/tty: require read access for controlling terminalJann Horn1-4/+27
This is mostly a hardening fix, given that write-only access to other users' ttys is usually only given through setgid tty executables. Signed-off-by: Jann Horn <[email protected]> Cc: [email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-10-04tty: don't leak cdev in tty_cdev_add()Leon Yu1-2/+7
Commit a3a10ce3429e ("Avoid usb reset crashes by making tty_io cdevs truly dynamic") which mixes using cdev_alloc() and cdev_init() is problematic. Subsequent call to cdev_init() after cdev_alloc() sets kobj release method from cdev_dynamic_release() to cdev_default_release() and thus makes it impossible to free allocated cdev. This patch also consolidates error path of cdev_add() as cdev can also leak here if things went wrong. Signed-off-by: Leon Yu <[email protected]> Fixes: a3a10ce3429e ("Avoid usb reset crashes by making tty_io cdevs truly dynamic") Acked-by: Richard Watts <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-08-03Avoid usb reset crashes by making tty_io cdevs truly dynamicRichard Watts1-8/+16
Avoid usb reset crashes by making tty_io cdevs truly dynamic Signed-off-by: Richard Watts <[email protected]> Reported-by: Duncan Mackintosh <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-07-23tty: Replace #ifdef TTY_DEBUG_HANGUP with tty_debug_hangup()Peter Hurley1-29/+18
Add tty_debug_hangup() macro which uses tty_debug to print the debug message; remove inlined #ifdefs. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-07-23tty: core: Add tty_debug() for printk(KERN_DEBUG) messagesPeter Hurley1-24/+17
Introduce tty_debug() macro to output uniform debug information for tty core debug messages (function name and tty name). Note: printk(KERN_DEBUG) is retained here over pr_debug() since messages can be enabled in non-DEBUG builds. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-07-23tty: core: Improve debug message contentPeter Hurley1-13/+16
Output the function name, tty name, and invariant failure (if applicable). Add the tty count to the tty_open() message. Fix the disassociate_ctty() message, which printed the NULL pointer and the wrong message. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-07-23tty: add missing rcu_read_lock for task_pgrpPatrick Donnelly1-5/+12
task_pgrp requires an rcu or tasklist lock to be obtained if the returned pid is to be dereferenced, which kill_pgrp does. Obtain an RCU lock for the duration of use. Signed-off-by: Patrick Donnelly <[email protected]> Reviewed-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-05-06tty: remove buf parameter from tty_name()Rasmus Villemoes1-17/+11
tty_name no longer uses the buf parameter, so remove it along with all the 64 byte stack buffers that used to be passed in. Mostly generated by the coccinelle script @depends on patch@ identifier buf; constant C; expression tty; @@ - char buf[C]; <+... - tty_name(tty, buf) + tty_name(tty) ...+> allmodconfig compiles, so I'm fairly confident the stack buffers weren't used for other purposes as well. Signed-off-by: Rasmus Villemoes <[email protected]> Reviewed-by: Peter Hurley <[email protected]> Acked-by: Jesper Nilsson <[email protected]> Acked-by: Dmitry Torokhov <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-05-06tty: return tty->name directly from tty_nameRasmus Villemoes1-5/+3
All users of tty_name pass the return value (the provided buffer) to some printf-like function. We can thus avoid the strcpy and, more importantly, later remove the buf parameter completely, eliminating the need for some 64 byte stack buffers. Signed-off-by: Rasmus Villemoes <[email protected]> Reviewed-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-05-06tty: constify return type of tty_nameRasmus Villemoes1-1/+1
All users of tty_name pass the result directly to a printf-like function. This means we can actually let tty_name return the literal "NULL tty" or tty->name directly, avoiding the strcpy and a lot of medium-sized stack buffers. In preparation for that, make the return type const char*. While at it, we can also constify the tty parameter. Signed-off-by: Rasmus Villemoes <[email protected]> Reviewed-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-03-26tty: clean up the tty time logic a bitGreg Kroah-Hartman1-2/+8
We only care if anything other than the lower 3 bits of the tty has changed, so just check that way, which makes it a bit faster, and more obvious what is going on. Also, document this for future developers to understand why we did this. Reported-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman [email protected]
2015-03-26tty: Use static attribute groups for sysfs entriesTakashi Iwai1-4/+10
Instead of manual calls of device_create_file() and device_remove_file(), pass the static attribute groups using device_create_with_groups(). Signed-off-by: Takashi Iwai <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-03-07tty: fix up atime/mtime mess, take fourJiri Slaby1-2/+2
This problem was taken care of three times already in * b0de59b5733d18b0d1974a060860a8b5c1b36a2e (TTY: do not update atime/mtime on read/write), * 37b7f3c76595e23257f61bd80b223de8658617ee (TTY: fix atime/mtime regression), and * b0b885657b6c8ef63a46bc9299b2a7715d19acde (tty: fix up atime/mtime mess, take three) But it still misses one point. As John Paul correctly points out, we do not care about setting date. If somebody ever changes wall time backwards (by mistake for example), tty timestamps are never updated until the original wall time passes. So check the absolute difference of times and if it large than "8 seconds or so", always update the time. That means we will update immediatelly when changing time. Ergo, CAP_SYS_TIME can foul the check, but it was always that way. Thanks John for serving me this so nicely debugged. Signed-off-by: Jiri Slaby <[email protected]> Reported-by: John Paul Perry <[email protected]> Cc: <[email protected]> # all, as b0b885657 was backported Acked-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2015-01-09tty: Prevent hw state corruption in exclusive mode reopenPeter Hurley1-4/+3
Exclusive mode ttys (TTY_EXCLUSIVE) do not allow further reopens; fail the condition before associating the file pointer and calling the driver open() method. Prevents DTR programming when the tty is already in exclusive mode. Reported-by: Shreyas Bethur <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Acked-by: Shreyas Bethur <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-26tty: Deletion of unnecessary checks before two function callsMarkus Elfring1-4/+2
The functions put_device() and tty_kref_put() test whether their argument is NULL and then return immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-06tty: warn on deprecated serial flagsJiri Slaby1-0/+21
When somebody calls TIOCSSERIAL ioctl with serial flags to set one of * ASYNC_SESSION_LOCKOUT * ASYNC_PGRP_LOCKOUT * ASYNC_CALLOUT_NOHUP * ASYNC_AUTOPROBE nothing happens. We actually ignore the flags for over a decade at least (I checked 2.6.0). So start yelling at users who use those flags, that they shouldn't. Signed-off-by: Jiri Slaby <[email protected]> Cc: Peter Hurley <[email protected]> Cc: Alan Cox <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Call methods in modern stylePeter Hurley1-6/+6
The use of older function ptr calling style, (*fn)(), makes static analysis more error-prone; replace with modern fn() style. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Replace open-coded test with tty_hung_up_p()Peter Hurley1-1/+1
tty_hung_up_p() is equivalent to the open-coded test in tty_open(). Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05Merge branch 'tty-linus' into 'tty-testing'Greg Kroah-Hartman1-3/+12
We need the fixes in drivers/tty/tty_io.c that were done in there for future patches in this branch. Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Flush ldisc buffer atomically with tty flip buffersPeter Hurley1-1/+1
tty_ldisc_flush() first clears the line discipline input buffer, then clears the tty flip buffers. However, this allows for existing data in the tty flip buffers to be added after the ldisc input buffer has been cleared, but before the flip buffers have been cleared. Add an optional ldisc parameter to tty_buffer_flush() to allow tty_ldisc_flush() to pass the ldisc to clear. NB: Initially, the plan was to do this automatically in tty_buffer_flush(). However, an audit of the behavior of existing line disciplines showed that performing a ldisc buffer flush on ioctl(TCFLSH) was not always the outcome. For example, some line disciplines have flush_buffer() methods but not ioctl() methods, so a ->flush_buffer() command would be unexpected. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Change tty lock order to master->slavePeter Hurley1-4/+6
When releasing the master pty, the slave pty also needs to be locked to prevent concurrent tty count changes for the slave pty and to ensure that only one parallel master and slave release observe the final close, and proceed to destruct the pty pair. Conversely, when releasing the slave pty, locking the master pty is not necessary (since the master's state can be inferred by the slave tty count). Introduce tty_lock_slave()/tty_unlock_slave() which acquires/releases the tty lock of the slave pty. Remove tty_lock_pair()/tty_unlock_pair(). Dropping the tty_lock is no longer required to re-establish a stable lock order. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Simplify tty_release() state checksPeter Hurley1-10/+9
The local o_tty variable in tty_release() is now accessed only when closing the pty master. Set o_tty to slave pty when closing pty master, otherwise NULL; use o_tty != NULL as replacement for pty_master. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Simplify tty_release_checks() interfacePeter Hurley1-3/+4
Passing the 'other' tty to tty_release_checks() only makes sense for a pty pair; make o_tty scope local instead. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Simplify tty_ldisc_release() interfacePeter Hurley1-1/+1
Passing the 'other' tty to tty_ldisc_release() only makes sense for a pty pair; make o_tty function local instead. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Fold pty pair handling into tty_flush_works()Peter Hurley1-5/+7
Perform work flush for both ends of a pty pair within tty_flush_works(), rather than calling twice. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Simplify pty pair teardown logicPeter Hurley1-19/+10
When the slave side closes and its tty count is 0, the pty pair can be destroyed; the master side must have already closed for the slave side tty count to be 0. Thus, only the pty master close must check if the slave side has closed by checking the slave tty count. Remove the pre-computed closing flags and check the actual count(s). Regular ttys are unaffected by this change. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Document check_tty_count() requires tty_lock heldPeter Hurley1-0/+1
Holding the tty_lock() is necessary to prevent concurrent changes to the tty count that may cause it to differ from the open file list count. The tty_lock() is already held at all call sites. NB: Note that the check for the pty master tty count is safe because the slave's tty_lock() is held while decrementing the pty master tty count. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Don't release tty locks for wait queue sanity checkPeter Hurley1-6/+2
Releasing the tty locks while waiting for the tty wait queues to be empty is no longer necessary nor desirable. Prior to "tty: Don't take tty_mutex for tty count changes", dropping the tty locks was necessary to reestablish the correct lock order between tty_mutex and the tty locks. Dropping the global tty_mutex was necessary; otherwise new ttys could not have been opened while waiting. However, without needing the global tty_mutex held, the tty locks for the releasing tty can now be held through the sleep. The sanity check is for abnormal conditions caused by kernel bugs, not for recoverable errors caused by misbehaving userspace; dropping the tty locks only allows the tty state to get more sideways. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Don't take tty_mutex for tty count changesPeter Hurley1-6/+0
Holding tty_mutex is no longer required to serialize changes to the tty_count or to prevent concurrent opens of closing ttys; tty_lock() is sufficient. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Remove TTY_CLOSINGPeter Hurley1-12/+2
Now that re-open is not permitted for a legacy BSD pty master, using TTY_CLOSING to indicate when a tty can be torn-down is no longer necessary. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Drop tty_mutex before tty reopenPeter Hurley1-8/+17
Holding tty_mutex for a tty re-open is no longer necessary since "tty: Clarify re-open behavior of master ptys". Because the slave tty count is no longer accessed by tty_reopen(), holding tty_mutex to prevent concurrent final tty_release() of the slave pty is not required. As with "tty: Re-open /dev/tty without tty_mutex", holding a tty kref until the tty_lock is acquired is sufficient to ensure the tty has not been freed, which, in turn, is sufficient to ensure the tty_lock can be safely acquired and the tty count can be safely retrieved. A non-zero tty count with the tty lock held guarantees that release_tty() has not run and cannot run concurrently with tty_reopen(). Change tty_driver_lookup_tty() to acquire the tty kref, which allows the tty_mutex to be dropped before acquiring the tty lock. Dropping the tty_mutex before attempting the tty_lock allows other ttys to be opened and released, without needing this tty_reopen() to complete. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Re-open /dev/tty without tty_mutexPeter Hurley1-26/+27
Opening /dev/tty (ie., the controlling tty for the current task) is always a re-open of the underlying tty. Because holding the tty_lock is sufficient for safely re-opening a tty, and because having a tty kref is sufficient for safely acquiring the tty_lock [1], tty_open_current_tty() does not require holding tty_mutex. Repurpose tty_open_current_tty() to perform the re-open itself and refactor tty_open(). [1] Analysis of safely re-opening the current tty w/o tty_mutex get_current_tty() gets a tty kref from the already kref'ed tty value of current->signal->tty while holding the sighand lock for the current task. This guarantees that the tty pointer returned from get_current_tty() points to a tty which remains referenceable while holding the kref. Although release_tty() may run concurrently, and thus the driver reference may be removed, release_one_tty() cannot have run, and won't while holding the tty kref. This, in turn, guarantees the tty_lock() can safely be acquired (since tty->magic and tty->legacy_mutex are still a valid dereferences). The tty_lock() also gets a tty kref to prevent the tty_unlock() from dereferencing a released tty. Thus, the kref returned from get_current_tty() can be released. Lastly, the first operation of tty_reopen() is to check the tty count. If non-zero, this ensures release_tty() is not running concurrently, and the driver references have not been removed. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Check tty->count instead of TTY_CLOSING in tty_reopen()Peter Hurley1-1/+1
Although perhaps not obvious, the TTY_CLOSING bit is set when the tty count has been decremented to 0 (which occurs while holding tty_lock). The only other case when tty count is 0 during a re-open is when a legacy BSD pty master has been opened in parallel but after the pty slave, which is unsupported and returns an error. Thus !tty->count contains the complete set of degenerate conditions under which a tty open fails. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Clarify re-open behavior of master ptysPeter Hurley1-11/+4
Re-opening master ptys is not allowed. Once opened and for the remaining lifetime of the master pty, its tty count is 1. If its tty count has dropped to 0, then the master pty was closed and TTY_CLOSING was set, and destruction may begin imminently. Besides the normal case of a legacy BSD pty master being re-opened (which always returns -EIO), this code is only reachable in 2 degenerate cases: 1. The pty master is the controlling terminal (this is possible through the TIOCSCTTY ioctl). pty masters are not designed to be controlling terminals and it's an oversight that tiocsctty() ever let that happen. The attempted open of /dev/tty will always fail. No known program does this. 2. The legacy BSD pty slave was opened first. The slave open will fail in pty_open() and tty_release() will commence. But before tty_release() claims the tty_mutex, there is a very small window where a parallel master open might succeed. In a test of racing legacy BSD slave and master parallel opens, where: slave open attempts: 10000 success:4527 failure:5473 master open attempts: 11728 success:5789 failure:5939 only 8 master open attempts would have succeeded reaching this code and successfully opened the master pty. This case is not possible with SysV ptys. Always return -EIO if a master pty is re-opened or the slave is opened first and the master opened in parallel (for legacy BSD ptys). Furthermore, now that changing the slave's count is not required, the tty_lock is sufficient for preventing concurrent changes to the tty being re-opened (or failing re-opening). Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Remove TTY_HUPPINGPeter Hurley1-11/+1
Now that tty_ldisc_hangup() does not drop the tty lock, it is no longer possible to observe TTY_HUPPING while holding the tty lock on another cpu. Remove TTY_HUPPING bit definition. Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
2014-11-05tty: Update code comment in __proc_set_tty()Peter Hurley1-1/+4
The session and foreground process group pid references will be non-NULL if tiocsctty() is stealing the controlling tty from another session (ie., arg == 1 in tiocsctty()). Signed-off-by: Peter Hurley <[email protected]> Reviewed-by: Alan Cox <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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