summaryrefslogtreecommitdiffstats
path: root/drivers/char/pty.c
Commit message (Collapse)AuthorAgeFilesLines
* pty: reconnect the BSD TIOCSPTLCK handling to legacy ptysLinus Torvalds2009-09-301-21/+26
| | | | | | | | | | | | | | | | | | | | David Howells noticed (due to the compiler warning about an unused 'pty_ops_bsd' variable) that we haven't actually been using the code that implements TIOCSPTLCK for legacy pty handling. It's been that way since 2.6.26, commit 3e8e88ca053150efdbecb45d8f481cf560ec808d to be exact ("pty: prepare for tty->ops changes"). DavidH initially submitted a patch just removing the dead code entirely, and since nobody has apparently ever complained, I'm not entirely sure that wouldn't be the right thing to do. But since the whole and only point of the legacy pty code is to be compatible with legacy distros that don't use the new unix98 pty model, let's just wire it up again. And clean it up a bit while we're at it. Acked-by: David Howells <dhowells@redhat.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty_write: don't do a tty_wakeup() when the buffers are fullLinus Torvalds2009-09-181-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | Commit ac89a9174 ("pty: don't limit the writes to 'pty_space()' inside 'pty_write()'") removed the pty_space() checking, in order to let the regular tty buffer code limit the buffering itself. That was all good, but as a subtle side effect it meant that we'd be doing a tty_wakeup() even in the case where the buffers were all filled up, and didn't actually make any progress on the write. Which sounds innocuous, but it interacts very badly with the ppp_async code, which has an infinite loop in ppp_async_push() that tries to push out data to the tty. When we call tty_wakeup(), that loop ends up thinking that progress was made (see the subtle interactions between XMIT_WAKEUP and 'tty_stuffed' for details). End result: one unhappy ppp user. Fixed by noticing when tty_insert_flip_string() didn't actually do anything, and then not doing any more processing (including, very much not calling tty_wakeup()). Bisected-and-tested-by: Peter Volkov <pva@gentoo.org> Cc: stable@kernel.org (2.6.31) Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: don't limit the writes to 'pty_space()' inside 'pty_write()'Linus Torvalds2009-09-051-9/+1
| | | | | | | | | | | | | | | | | | | | | | | | The whole write-room thing is something that is up to the _caller_ to worry about, not the pty layer itself. The total buffer space will still be limited by the buffering routines themselves, so there is no advantage or need in having pty_write() artificially limit the size somehow. And what happened was that the caller (the n_tty line discipline, in this case) may have verified that there is room for 2 bytes to be written (for NL -> CRNL expansion), and it used to then do those writes as two single-byte writes. And if the first byte written (CR) then caused a new tty buffer to be allocated, pty_space() may have returned zero when trying to write the second byte (LF), and then incorrectly failed the write - leading to a lost newline character. This should finally fix http://bugzilla.kernel.org/show_bug.cgi?id=14015 Reported-by: Mikael Pettersson <mikpe@it.uu.se> Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: fix data loss when stopped (^S/^Q)Linus Torvalds2009-08-101-0/+2
| | | | | | | | | | | | | | | | | | | | | Commit d945cb9cc ("pty: Rework the pty layer to use the normal buffering logic") dropped the test for 'tty->stopped' in pty_write_room(), which then causes the n_tty line discipline thing to not throttle the data properly when the tty is stopped. So instead of pausing the write due to the tty being stopped, the ldisc layer would go ahead and push it down to the pty. The pty write() routine would then refuse to take the data (because it _did_ check 'stopped'), and the data wouldn't actually be written. This whole stopped test should eventually be moved into the tty ldisc layer rather than have low-level tty drivers care about these things, but right now the fix is to just re-instate the missing pty 'stopped' handling. Reported-and-tested-by: Artur Skawina <art.08.09@gmail.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: avoid forcing 'low_latency' tty flagOGAWA Hirofumi2009-07-291-2/+0
| | | | | | | | | | | | | | | | | | | | | | | We really don't want to mark the pty as a low-latency device, because as Alan points out, the ->write method can be called from an IRQ (ppp?), and that means we can't use ->low_latency=1 as we take mutexes in the low_latency case. So rather than using low_latency to force the written data to be pushed to the ldisc handling at 'write()' time, just make the reader side (or the poll function) do the flush when it checks whether there is data to be had. This also fixes the problem with lost data in an emacs compile buffer (bugzilla 13815), and we can thus revert the low_latency pty hack (commit 3a54297478e6578f96fd54bf4daa1751130aca86: "pty: quickfix for the pty ENXIO timing problems"). Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> [ Modified to do the tty_flush_to_ldisc() inside input_available_p() so that it triggers for both read and poll() - Linus] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: quickfix for the pty ENXIO timing problemsAlan Cox2009-07-271-0/+2
| | | | | | | | This also makes close stall in the normal case which is apparently needed to fix emacs Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* headers: smp_lock.h reduxAlexey Dobriyan2009-07-121-0/+1
| | | | | | | | | | | | | * Remove smp_lock.h from files which don't need it (including some headers!) * Add smp_lock.h to files which do need it * Make smp_lock.h include conditional in hardirq.h It's needed only for one kernel_locked() usage which is under CONFIG_PREEMPT This will make hardirq.h inclusion cheaper for every PREEMPT=n config (which includes allmodconfig/allyesconfig, BTW) Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: Rework the pty layer to use the normal buffering logicAlan Cox2009-07-081-95/+59
| | | | | | | | | | | This fixes the ppp problems and various other issues with call locking caused by one side of a pty called in one locking context trying to match another with differing rules on the other side. We also get a big slack space to work with that means we can bury the flow control deadlock case for any conceivable real world situation. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: Narrow the race on ldisc lockingAlan Cox2009-06-161-13/+40
| | | | | | | | | | The pty code has always been buggy on its ldisc handling. The recent changes made the window for the race much bigger. Pending fixing it properly which is not at all trivial, at least make the race small again so we don't disrupt other dev work. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: rewrite the ldisc lockingAlan Cox2009-06-111-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are several pretty much unfixable races in the old ldisc code, especially with respect to pty behaviour and also to hangup. It's easier to rewrite the code than simply try and patch it up. This patch - splits the ldisc from the tty (so we will be able to refcount it more cleanly later) - introduces a mutex lock for ldisc changing on an active device - fixes the complete mess that hangup caused - implements hopefully correct setldisc/close/hangup locking There are still some problems around pty pairs that have always been there but at least it is now possible to understand the code and fix further problems. This fixes the following known bugs - hang up can leak ldisc references - hang up may not call open/close on ldisc in a matched way - pty/tty pairs can deadlock during an ldisc change - reading the ldisc proc files can cause every ldisc to be loaded and probably a few other of the mysterious ldisc race reports. I'm sure it also adds the odd new one. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: Fix a commentAlan Cox2009-06-111-1/+0
| | | | | | | We fixed the globals, so now fix the comment Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: Fix documentationAlan Cox2009-01-121-3/+1
| | | | | | | | The pty changes and updates for window sizing forgot to correct the kerneldoc Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Make various things staticRoel Kluin2009-01-081-1/+1
| | | | | | | | | | Building an allnoconfig kernel, sparse asked whether these could be static, so I checked, and they are only used in the file where they are declared. Signed-off-by: Roel Kluin <roel.kluin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: PTYs set TTY_DO_WRITE_WAKEUP when they don't need toAlan Cox2009-01-021-3/+0
| | | | | | | | | The write wakeup is done anyway for the poll while DO_WRITE_WAKUP is cleared, set and managed by the ldisc layer and is no business of the pty code. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: simplify resizeAlan Cox2009-01-021-1/+53
| | | | | | | | We have special case logic for resizing pty/tty pairs. We also have a per driver resize method so for the pty case we should use it. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: simplify unix98 allocationAlan Cox2008-10-131-11/+7
| | | | | | | We need both termios and termios_locked so allocate them as one Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: Fix allocation failure double freeAlan Cox2008-10-131-2/+0
| | | | | | | | | The updating and moving around of the pty code added a bug where both the helper and caller free the main tty struct (the pty driver must free the o_tty pair itself however). Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: Coding style and polishAlan Cox2008-10-131-42/+44
| | | | | | | We've done the heavy lifting now its time to mop up a bit Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add an instance parameter devpts interfacesSukadev Bhattiprolu2008-10-131-8/+10
| | | | | | | | | | | | | | | | | Pass-in 'inode' or 'tty' parameter to devpts interfaces. With multiple devpts instances, these parameters will be used in subsequent patches to identify the instance of devpts mounted. The parameters also help simplify devpts implementation. Changelog[v3]: - minor changes due to merge with ttydev updates - rename parameters to emphasize they are ptmx or pts inodes - pass-in tty_struct * to devpts_pty_kill() (this will help cleanup the get_node() call in a subsequent patch) Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: extract the pty init time special casesAlan Cox2008-10-131-12/+114
| | | | | | | | The majority of the remaining init_dev code is pty special cases. We refactor this code into the driver->install method. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: Finish fixing up the init_dev interface to use ERR_PTRAlan Cox2008-10-131-2/+4
| | | | | | | Original suggestion and proposal from Sukadev Bhattiprolu. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: More driver operationsAlan Cox2008-10-131-0/+16
| | | | | | | | | | We have the lookup operation abstracted which is nice for pty cleanup but we really want to abstract the add/remove entries as well so that we can pull the pty code out of the tty core and create a clear defined interface for the tty driver table. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: kref the tty driver objectAlan Cox2008-10-131-1/+4
| | | | | Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: Clean up the tty_init_dev changes furtherAlan Cox2008-10-131-1/+48
| | | | | | | | Fix up the naming, style and extract some bits of code into the driver specific code Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: Remove more special casing and out of place codeAlan Cox2008-10-131-0/+78
| | | | | | | | | Carry on pushing code out of tty_io when it belongs to other drivers. I'm not 100% happy with some of this and it will be worth revisiting some of the exports later when the restructuring work is done. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: shutdown methodAlan Cox2008-10-131-4/+11
| | | | | | | | | | | | | | | | | | | Right now there are various drivers that try to use tty->count to know when they get the final close. Aristeau Rozanski showed while debugging the vt sysfs race that this isn't entirely safe. Instead of driver side tricks to work around this introduce a shutdown which is called when the tty is being destructed. This also means that the shutdown method is tied into the refcounting. Use this to rework the console close/sysfs logic. Remove lots of special case code from the tty core code. The pty code can now have a shutdown() method that replaces the special case hackery in the tree free up paths. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: Ldisc revampAlan Cox2008-07-201-5/+5
| | | | | | | | | | | | Move the line disciplines towards a conventional ->ops arrangement. For the moment the actual 'tty_ldisc' struct in the tty is kept as part of the tty struct but this can then be changed if it turns out that when it all settles down we want to refcount ldiscs separately to the tty. Pull the ldisc code out of /proc and put it with our ldisc code. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pty: prepare for tty->ops changesAlan Cox2008-04-301-3/+26
| | | | | | | | | | | | We are about to change the tty layer to avoid keeping private copies of all the methods in each tty. We have to update the pty layer first as it currently patches the ioctl method according to the tty type. Use multiple tty operations sets instead. Signed-off-by: Alan Cox <alan@redhat.com> Acked-by: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tty: BKL pushdownAlan Cox2008-04-301-0/+3
| | | | | | | | | | | | | | | | | - Push the BKL down into the line disciplines - Switch the tty layer to unlocked_ioctl - Introduce a new ctrl_lock spin lock for the control bits - Eliminate much of the lock_kernel use in n_tty - Prepare to (but don't yet) call the drivers with the lock dropped on the paths that historically held the lock BKL now primarily protects open/close/ldisc change in the tty layer [jirislaby@gmail.com: a couple of fixes] Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sysctl: simplify the pty sysctl logicEric W. Biederman2007-10-181-1/+23
| | | | | | | | | | | | | Instead of having a bunch of ifdefs in sysctl.c move all of the pty sysctl logic into drivers/char/pty.c As well as cleaning up the logic this prevents sysctl_check_table from complaining that the root table has a NULL data pointer on something with generic methods. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* PTY: add kernel parameter to overwrite legacy pty countKay Sievers2007-10-121-2/+7
| | | | | | Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* [PATCH] remove many unneeded #includes of sched.hTim Schmielau2007-02-141-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | After Al Viro (finally) succeeded in removing the sched.h #include in module.h recently, it makes sense again to remove other superfluous sched.h includes. There are quite a lot of files which include it but don't actually need anything defined in there. Presumably these includes were once needed for macros that used to live in sched.h, but moved to other header files in the course of cleaning it up. To ease the pain, this time I did not fiddle with any header files and only removed #includes from .c-files, which tend to cause less trouble. Compile tested against 2.6.20-rc2 and 2.6.20-rc2-mm2 (with offsets) on alpha, arm, i386, ia64, mips, powerpc, and x86_64 with allnoconfig, defconfig, allmodconfig, and allyesconfig as well as a few randconfigs on x86_64 and all configs in arch/arm/configs on arm. I also checked that no new warnings were introduced by the patch (actually, some warnings are removed that were emitted by unnecessarily included header files). Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] tty: switch to ktermiosAlan Cox2006-12-081-1/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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] const struct tty_operationsJeff Dike2006-10-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | As part of an SMP cleanliness pass over UML, I consted a bunch of structures in order to not have to document their locking. One of these structures was a struct tty_operations. In order to const it in UML without introducing compiler complaints, the declaration of tty_set_operations needs to be changed, and then all of its callers need to be fixed. This patch declares all struct tty_operations in the tree as const. In all cases, they are static and used only as input to tty_set_operations. As an extra check, I ran an i386 allyesconfig build which produced no extra warnings. 53 drivers are affected. I checked the history of a bunch of them, and in most cases, there have been only a handful of maintenance changes in the last six months. serial_core.c was the busiest one that I looked at. Signed-off-by: Jeff Dike <jdike@addtoit.com> Acked-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Remove obsolete #include <linux/config.h>Jörn Engel2006-06-301-1/+0
| | | | | Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/devfs-2.6Linus Torvalds2006-06-291-6/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/devfs-2.6: (22 commits) [PATCH] devfs: Remove it from the feature_removal.txt file [PATCH] devfs: Last little devfs cleanups throughout the kernel tree. [PATCH] devfs: Rename TTY_DRIVER_NO_DEVFS to TTY_DRIVER_DYNAMIC_DEV [PATCH] devfs: Remove the tty_driver devfs_name field as it's no longer needed [PATCH] devfs: Remove the line_driver devfs_name field as it's no longer needed [PATCH] devfs: Remove the videodevice devfs_name field as it's no longer needed [PATCH] devfs: Remove the gendisk devfs_name field as it's no longer needed [PATCH] devfs: Remove the miscdevice devfs_name field as it's no longer needed [PATCH] devfs: Remove the devfs_fs_kernel.h file from the tree [PATCH] devfs: Remove devfs_remove() function from the kernel tree [PATCH] devfs: Remove devfs_mk_cdev() function from the kernel tree [PATCH] devfs: Remove devfs_mk_bdev() function from the kernel tree [PATCH] devfs: Remove devfs_mk_symlink() function from the kernel tree [PATCH] devfs: Remove devfs_mk_dir() function from the kernel tree [PATCH] devfs: Remove devfs_*_tape() functions from the kernel tree [PATCH] devfs: Remove devfs support from the sound subsystem [PATCH] devfs: Remove devfs support from the ide subsystem. [PATCH] devfs: Remove devfs support from the serial subsystem [PATCH] devfs: Remove devfs from the init code [PATCH] devfs: Remove devfs from the partition code ...
| * [PATCH] devfs: Rename TTY_DRIVER_NO_DEVFS to TTY_DRIVER_DYNAMIC_DEVGreg Kroah-Hartman2006-06-261-2/+2
| | | | | | | | | | | | | | | | | | | | I've always found this flag confusing. Now that devfs is no longer around, it has been renamed, and the documentation for when this flag should be used has been updated. Also fixes all drivers that use this flag. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| * [PATCH] devfs: Remove the tty_driver devfs_name field as it's no longer neededGreg Kroah-Hartman2006-06-261-2/+0
| | | | | | | | | | | | Also fixes all drivers that set this field. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| * [PATCH] devfs: Remove the devfs_fs_kernel.h file from the treeGreg Kroah-Hartman2006-06-261-1/+0
| | | | | | | | | | | | Also fixes up all files that #include it. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| * [PATCH] devfs: Remove devfs_mk_dir() function from the kernel treeGreg Kroah-Hartman2006-06-261-1/+0
| | | | | | | | | | | | Removes the devfs_mk_dir() function and all callers of it. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* | [PATCH] remove TTY_DONT_FLIPPaul Fulghum2006-06-281-1/+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] TTY layer buffering revampAlan Cox2006-01-101-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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] pty_chars_in_buffer oops fixJason Baron2005-09-091-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The idea of this patch is to lock both sides of a ptmx/pty pair during line discipline changing. This is needed to ensure that say a poll on one side of the pty doesn't occur while the line discipline is actively being changed. This resulted in an oops reported on lkml, see: http://marc.theaimsgroup.com/?l=linux-kernel&m=111342171410005&w=2 A 'hacky' approach was previously implmemented which served to eliminate the poll vs. line discipline changing race. However, this patch takes a more general approach to the issue. The patch only adds locking on a less often used path, the line-discipline changing path, as opposed to locking the ptmx/pty pair on read/write/poll paths. The patch below, takes both ldisc locks in either order b/c the locks are both taken under the same spinlock(). I thought about locking the ptmx/pty separately, such as master always first but that introduces a 3 way deadlock. For example, process 1 does a blocking read on the slave side. Then, process 2 does an ldisc change on the slave side, which acquires the master ldisc lock but not the slave's. Finally, process 3 does a write which blocks on the process 2's ldisc reference. This patch does introduce some changes in semantics. For example, a line discipline change on side 'a' of a ptmx/pty pair, will now wait for a read/write to complete on the other side, or side 'b'. The current behavior is to simply wait for any read/writes on only side 'a', not both sides 'a' and 'b'. I think this behavior makes sense, but I wanted to point it out. I've tested the patch with a bunch of read/write/poll while changing the line discipline out from underneath. This patch obviates the need for the above "hide the problem" patch. Signed-off-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+412
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!
OpenPOWER on IntegriCloud