linux/drivers/tty/tty_io.c, branch v4.9

Merge 4.6-rc7 into tty-next

2016-05-09T07:39:13Z

We want the pty fixes in here as well so that patches can build on it. Signed-off-by: Greg Kroah-Hartman

tty: Remove stale parameter comment

2016-04-30T16:26:55Z

noctty was removed as a parameter by commit 11e1d4aa4da ("tty: Consolidate noctty check in tty_open()"). Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Remove unused TTY_NUMBER() macro

2016-04-30T16:26:55Z

TTY_NUMBER() has been unused since v2.5.71; removed by "[PATCH] callout removal: callout is gone". Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Replace TTY_IO_ERROR bit tests with tty_io_error()

2016-04-30T16:26:55Z

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 Signed-off-by: Greg Kroah-Hartman

devpts: more pty driver interface cleanups

2016-04-26T22:47:32Z

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 Cc: Peter Anvin Cc: Andy Lutomirski Cc: Al Viro Cc: Peter Hurley Cc: Serge Hallyn Cc: Willy Tarreau Cc: Aurelien Jarno Cc: Alan Cox Cc: Jann Horn Cc: Greg KH Cc: Jiri Slaby Cc: Florian Weimer Signed-off-by: Linus Torvalds

tty: Fix merge of "tty: Refactor tty_open()"

2016-04-01T03:49:39Z

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 Signed-off-by: Greg Kroah-Hartman

tty: Fix UML console breakage

2016-04-01T00:14:14Z

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 Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Fix ioctl(FIOASYNC) on hungup file

2016-01-28T19:58:02Z

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 Signed-off-by: Greg Kroah-Hartman

tty: Add fasync() hung up file operation

2016-01-28T19:58:02Z

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 Signed-off-by: Greg Kroah-Hartman

tty, n_tty: Remove fasync() ldisc notification

2016-01-28T19:58:02Z

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 Signed-off-by: Greg Kroah-Hartman