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path: root/drivers/char/n_tty.c
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* [PATCH] tty: update the tty layer to work with struct pidEric W. Biederman2007-02-121-6/+6
| | | | | | | | | | | | | | | | | Of kernel subsystems that work with pids the tty layer is probably the largest consumer. But it has the nice virtue that the assiation with a session only lasts until the session leader exits. Which means that no reference counting is required. So using struct pid winds up being a simple optimization to avoid hash table lookups. In the long term the use of pid_nr also ensures that when we have multiple pid spaces mixed everything will work correctly. Signed-off-by: Eric W. Biederman <eric@maxwell.lnxi.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] pid: replace is_orphaned_pgrp with is_current_pgrp_orphanedEric W. Biederman2007-02-121-1/+1
| | | | | | | | | | | | | | | | | | | Every call to is_orphaned_pgrp passed in process_group(current) which is racy with respect to another thread changing our process group. It didn't bite us because we were dealing with integers and the worse we would get would be a stale answer. In switching the checks to use struct pid to be a little more efficient and prepare the way for pid namespaces this race became apparent. So I simplified the calls to the more specialized is_current_pgrp_orphaned so I didn't have to worry about making logic changes to avoid the race. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] tty: remove useless memory barrierRalf Baechle2006-12-131-1/+0
| | | | | | | | | | I don't see why there is a memory barrier in copy_from_read_buf() at all. Even if it was useful spin_unlock_irqrestore implies a barrier. Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] tty: switch to ktermiosAlan Cox2006-12-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the grungy swap all the occurrences in the right places patch that goes with the updates. At this point we have the same functionality as before (except that sgttyb() returns speeds not zero) and are ready to begin turning new stuff on providing nobody reports lots of bugs If you are a tty driver author converting an out of tree driver the only impact should be termios->ktermios name changes for the speed/property setting functions from your upper layers. If you are implementing your own TCGETS function before then your driver was broken already and its about to get a whole lot more painful for you so please fix it 8) Also fill in c_ispeed/ospeed on init for most devices, although the current code will do this for you anyway but I'd like eventually to lose that extra paranoia [akpm@osdl.org: bluetooth fix] [mp3@de.ibm.com: sclp fix] [mp3@de.ibm.com: warning fix for tty3270] [hugh@veritas.com: fix tty_ioctl powerpc build] [jdike@addtoit.com: uml: fix ->set_termios declaration] Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Martin Peschke <mp3@de.ibm.com> Acked-by: Peter Oberparleiter <oberpar@de.ibm.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] remove TTY_DONT_FLIPPaul Fulghum2006-06-281-5/+1
| | | | | | | | | | | | | | | | | | | | | Remove TTY_DONT_FLIP tty flag. This flag was introduced in 2.1.X kernels to prevent the N_TTY line discipline functions read_chan() and n_tty_receive_buf() from running at the same time. 2.2.15 introduced tty->read_lock to protect access to the N_TTY read buffer, which is the only state requiring protection between these two functions. The current TTY_DONT_FLIP implementation is broken for SMP, and is not universally honored by drivers that send data directly to the line discipline receive_buf function. Because TTY_DONT_FLIP is not necessary, is broken in implementation, and is not universally honored, it is removed. Signed-off-by: Paul Fulghum <paulkf@microgate.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fix for the PPTP hangs that have been reportedPaul Mackerras2006-06-111-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | People have been reporting that PPP connections over ptys, such as used with PPTP, will hang randomly when transferring large amounts of data, for instance in http://bugzilla.kernel.org/show_bug.cgi?id=6530. I have managed to reproduce the problem, and the patch below fixes the actual cause. The problem is not in fact in ppp_async.c but in n_tty.c. What happens is that when pptp reads from the pty, we call read_chan() in drivers/char/n_tty.c on the master side of the pty. That copies all the characters out of its buffer to userspace and then calls check_unthrottle(), which calls the pty unthrottle routine, which calls tty_wakeup on the slave side, which calls ppp_asynctty_wakeup, which calls tasklet_schedule. So far so good. Since we are in process context, the tasklet runs immediately and calls ppp_async_process(), which calls ppp_async_push, which calls the tty->driver->write function to send some more output. However, tty->driver->write() returns zero, because the master tty->receive_room is still zero. We haven't returned from check_unthrottle() yet, and read_chan() only updates tty->receive_room _after_ calling check_unthrottle. That means that the driver->write call in ppp_async_process() returns 0. That would be fine if we were going to get a subsequent wakeup call, but we aren't (we just had it, and the buffer is now empty). The solution is for n_tty.c to update tty->receive_room _before_ calling the driver unthrottle routine. The patch below does this. With this patch I was able to transfer a 900MB file over a PPTP connection (taking about 25 minutes), whereas without the patch the connection would always stall in under a minute. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sem2mutex: ttyIngo Molnar2006-03-231-5/+5
| | | | | | | | | | | | | Semaphore to mutex conversion. The conversion was generated via scripts, and the result was validated automatically via a script as well. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] TTY layer buffering revampAlan Cox2006-01-101-29/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The API and code have been through various bits of initial review by serial driver people but they definitely need to live somewhere for a while so the unconverted drivers can get knocked into shape, existing drivers that have been updated can be better tuned and bugs whacked out. This replaces the tty flip buffers with kmalloc objects in rings. In the normal situation for an IRQ driven serial port at typical speeds the behaviour is pretty much the same, two buffers end up allocated and the kernel cycles between them as before. When there are delays or at high speed we now behave far better as the buffer pool can grow a bit rather than lose characters. This also means that we can operate at higher speeds reliably. For drivers that receive characters in blocks (DMA based, USB and especially virtualisation) the layer allows a lot of driver specific code that works around the tty layer with private secondary queues to be removed. The IBM folks need this sort of layer, the smart serial port people do, the virtualisers do (because a virtualised tty typically operates at infinite speed rather than emulating 9600 baud). Finally many drivers had invalid and unsafe attempts to avoid buffer overflows by directly invoking tty methods extracted out of the innards of work queue structs. These are no longer needed and all go away. That fixes various random hangs with serial ports on overflow. The other change in here is to optimise the receive_room path that is used by some callers. It turns out that only one ldisc uses receive room except asa constant and it updates it far far less than the value is read. We thus make it a variable not a function call. I expect the code to contain bugs due to the size alone but I'll be watching and squashing them and feeding out new patches as it goes. Because the buffers now dynamically expand you should only run out of buffering when the kernel runs out of memory for real. That means a lot of the horrible hacks high performance drivers used to do just aren't needed any more. Description: tty_insert_flip_char is an old API and continues to work as before, as does tty_flip_buffer_push() [this is why many drivers dont need modification]. It does now also return the number of chars inserted There are also tty_buffer_request_room(tty, len) which asks for a buffer block of the length requested and returns the space found. This improves efficiency with hardware that knows how much to transfer. and tty_insert_flip_string_flags(tty, str, flags, len) to insert a string of characters and flags For a smart interface the usual code is len = tty_request_buffer_room(tty, amount_hardware_says); tty_insert_flip_string(tty, buffer_from_card, len); More description! At the moment tty buffers are attached directly to the tty. This is causing a lot of the problems related to tty layer locking, also problems at high speed and also with bursty data (such as occurs in virtualised environments) I'm working on ripping out the flip buffers and replacing them with a pool of dynamically allocated buffers. This allows both for old style "byte I/O" devices and also helps virtualisation and smart devices where large blocks of data suddenely materialise and need storing. So far so good. Lots of drivers reference tty->flip.*. Several of them also call directly and unsafely into function pointers it provides. This will all break. Most drivers can use tty_insert_flip_char which can be kept as an API but others need more. At the moment I've added the following interfaces, if people think more will be needed now is a good time to say int tty_buffer_request_room(tty, size) Try and ensure at least size bytes are available, returns actual room (may be zero). At the moment it just uses the flipbuf space but that will change. Repeated calls without characters being added are not cumulative. (ie if you call it with 1, 1, 1, and then 4 you'll have four characters of space. The other functions will also try and grow buffers in future but this will be a more efficient way when you know block sizes. int tty_insert_flip_char(tty, ch, flag) As before insert a character if there is room. Now returns 1 for success, 0 for failure. int tty_insert_flip_string(tty, str, len) Insert a block of non error characters. Returns the number inserted. int tty_prepare_flip_string(tty, strptr, len) Adjust the buffer to allow len characters to be added. Returns a buffer pointer in strptr and the length available. This allows for hardware that needs to use functions like insl or mencpy_fromio. Signed-off-by: Alan Cox <alan@redhat.com> Cc: Paul Fulghum <paulkf@microgate.com> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: John Hawkes <hawkes@sgi.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] gfp_t: remaining bits of drivers/*Al Viro2005-10-281-1/+1
| | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] char/n_tty: fix sparse warnings (__nocast type)Victor Fusco2005-09-101-1/+1
| | | | | | | | | Fix the sparse warning "implicit cast to nocast type" Signed-off-by: Victor Fusco <victor@cetuc.puc-rio.br> Signed-off-by: Domen Puncer <domen@coderock.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] tty output lossage fixRoman Zippel2005-07-071-18/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The patch fixes a few corner cases around tty line editing with very long input lines: - n_tty_receive_char(): don't simply drop eol characters, otherwise canon_data isn't increased and the reader isn't woken up. - n_tty_receive_room(): If there is no newline pending and the edit buffer is full, allow only a single character to be written (until eol is found and the line is flushed), so characters from the next line aren't dropped. - write_chan(): if an incomplete line was written, continue writing until write() returns 0, otherwise it might not write the eol character to flush the line and the writer goes to sleep without ever being woken up. BTW the core problem is that part of this should be handled in the receive_buf path, but for this it has to return the number of written characters, as the amount of written characters may not be the same as the amount of characters going into the write buffer, so the receive_room() usage in pty_write() is not really reliable. Alan said: The problem looks valid. The behaviour of 'traditional unix' appears to be the following If you exceed the line limit then beep and drop the character Always allow EOL to complete a canonical line input Always do signal/control processing if enabled Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Linux-2.6.12-rc2Linus Torvalds2005-04-161-0/+1562
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!