kernel.git/drivers/tty/tty_port.c, branch linux-4.11.y

Revert "tty_port: register tty ports with serdev bus"

2017-06-07T10:10:06Z

commit d3ba126a226a6b6da021ebfea444a2a807cde945 upstream. This reverts commit 8ee3fde047589dc9c201251f07d0ca1dc776feca. The new serdev bus hooked into the tty layer in tty_port_register_device() by registering a serdev controller instead of a tty device whenever a serdev client is present, and by deregistering the controller in the tty-port destructor. This is broken in several ways: Firstly, it leads to a NULL-pointer dereference whenever a tty driver later deregisters its devices as no corresponding character device will exist. Secondly, far from every tty driver uses tty-port refcounting (e.g. serial core) so the serdev devices might never be deregistered or deallocated. Thirdly, deregistering at tty-port destruction is too late as the underlying device and structures may be long gone by then. A port is not released before an open tty device is closed, something which a registered serdev client can prevent from ever happening. A driver callback while the device is gone typically also leads to crashes. Many tty drivers even keep their ports around until the driver is unloaded (e.g. serial core), something which even if a late callback never happens, leads to leaks if a device is unbound from its driver and is later rebound. The right solution here is to add a new tty_port_unregister_device() helper and to never call tty_device_unregister() whenever the port has been claimed by serdev, but since this requires modifying just about every tty driver (and multiple subsystems) it will need to be done incrementally. Reverting the offending patch is the first step in fixing the broken lifetime assumptions. A follow-up patch will add a new pair of tty-device registration helpers, which a vetted tty driver can use to support serdev (initially serial core). When every tty driver uses the serdev helpers (at least for deregistration), we can add serdev registration to tty_port_register_device() again. Note that this also fixes another issue with serdev, which currently allocates and registers a serdev controller for every tty device registered using tty_port_device_register() only to immediately deregister and deallocate it when the corresponding OF node or serdev child node is missing. This should be addressed before enabling serdev for hot-pluggable buses. Signed-off-by: Johan Hovold Reviewed-by: Rob Herring Signed-off-by: Greg Kroah-Hartman

sched/headers: Prepare to move signal wakeup & sigpending methods from into

2017-03-02T07:42:32Z

Fix up affected files that include this signal functionality via sched.h. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

tty_port: register tty ports with serdev bus

2017-02-03T09:17:02Z

Register a serdev controller with the serdev bus when a tty_port is registered. This creates the serdev controller and create's serdev devices for any DT child nodes of the tty_port's parent (i.e. the UART device). Signed-off-by: Rob Herring Reviewed-By: Sebastian Reichel Tested-By: Sebastian Reichel Signed-off-by: Greg Kroah-Hartman

tty_port: Add port client functions

2017-02-03T09:17:02Z

Introduce a client (upward direction) operations struct for tty_port clients. Initially supported operations are for receiving data and write wake-up. This will allow for having clients other than an ldisc. Convert the calls to the ldisc to use the client ops as the default operations. Signed-off-by: Rob Herring Reviewed-By: Sebastian Reichel Tested-By: Sebastian Reichel Signed-off-by: Greg Kroah-Hartman

tty_port: make tty_port_register_device wrap tty_port_register_device_attr

2017-01-19T16:22:34Z

tty_register_device is just a wrapper for tty_register_device_attr with NULL passed for drvdata and attr_grp. So similarly make tty_port_register_device a wrapper of tty_port_register_device_attr so that additions don't have to be made in both functions. Signed-off-by: Rob Herring Reviewed-by: Andy Shevchenko Reviewed-By: Sebastian Reichel Signed-off-by: Greg Kroah-Hartman

tty_port: allow a port to be opened with a tty that has no file handle

2017-01-19T16:22:34Z

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 Reviewed-by: Andy Shevchenko Reviewed-By: Sebastian Reichel Signed-off-by: Rob Herring Signed-off-by: Greg Kroah-Hartman

tty: Replace ASYNC_INITIALIZED bit and update atomically

2016-04-30T16:26:55Z

Replace ASYNC_INITIALIZED bit in the tty_port::flags field with TTY_PORT_INITIALIZED bit in the tty_port::iflags field. Introduce helpers tty_port_set_initialized() and tty_port_initialized() to abstract atomic bit ops. Note: the transforms for test_and_set_bit() and test_and_clear_bit() are unnecessary as the state transitions are already mutually exclusive; the tty lock prevents concurrent open/close/hangup. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Replace ASYNC_NORMAL_ACTIVE bit and update atomically

2016-04-30T16:26:55Z

Replace ASYNC_NORMAL_ACTIVE bit in the tty_port::flags field with TTY_PORT_ACTIVE bit in the tty_port::iflags field. Introduce helpers tty_port_set_active() and tty_port_active() to abstract atomic bit ops. Extract state changes from port lock sections, as this usage is broken and confused; the state transitions are protected by the tty lock (which mutually excludes parallel open/close/hangup), and no user tests the active state while holding the port lock. 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

tty: Remove ASYNC_CLOSING

2016-01-28T22:19:12Z

The tty core no longer provides nor uses ASYNC_CLOSING; remove from tty_port_close_start() and tty_port_close_end() as well as tty drivers which open-code these state changes. Unfortunately, even though the bit is masked from userspace, its inclusion in a uapi header precludes removing the macro. Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: linux-s390@vger.kernel.org Cc: Mikael Starvik Cc: Jesper Nilsson Cc: linux-cris-kernel@axis.com Cc: Samuel Ortiz Cc: "David S. Miller" Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman