History log of /drivers/s390/char/sclp_vt220.c
Revision Date Author Comments (<<< Hide modified files) (Show modified files >>>)
5a0e3ad6af8660be21ca98a971cd00f331318c05 24-Mar-2010 Tejun Heo <tj@kernel.org> include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.

2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).

* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
/drivers/s390/char/sclp_vt220.c
0b665d770d2d4dca8e9ea53129735fe214838ec9 27-Jan-2010 Hendrik Brueckner <brueckner@linux.vnet.ibm.com> [S390] sclp_vt220: set initial terminal window size

When opening a SCLP VT220 terminal, the terminal window size is not
initialized (defaults to zero).
Since the SCLP VT220 terminal supports only 80x24, explicitly set
the window size to prevent (n)curses applications from guessing
the default setting.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
ac522b638dcb549f9d33085c6fadea88a5f826ae 14-Oct-2009 Michael Holzheu <michael.holzheu@linux.vnet.ibm.com> [S390] sclp_vt220 build fix

Fix this build error:

next-20091013 randconfig build on s390x build breaks with

drivers/s390/built-in.o:(.data+0x3354): undefined reference to `sclp_vt220_pm_event_fn'

Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <michael.holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
5c0792f6924333290ec3ca31c02e6555d73dba04 22-Jun-2009 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] vt220 console: convert from bootmem to slab

The slab allocator is earlier available so convert the
bootmem allocations to slab/gfp allocations.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
62b7494209495847269a6ce0504cbefd23d42eb1 16-Jun-2009 Michael Holzheu <holzheu@de.ibm.com> [S390] pm: power management support for SCLP drivers.

The SCLP base driver defines a new notifier call back for all upper level SCLP
drivers, like the SCLP console, etc. This guarantees that in suspend first the
upper level drivers are suspended and afterwards the SCLP base driver. For
resume it is the other way round. The SCLP base driver itself registers a
new platform device at the platform bus and gets PM notifications via
the dev_pm_ops.

In suspend, the SCLP base driver switches off the receiver and sender mask
This is done in sclp_deactivate(). After suspend all new requests will be
rejected with -EIO and no more interrupts will be received, because the masks
are switched off. For resume the sender and receiver masks are reset in
the sclp_reactivate() function.

When the SCLP console is suspended, all new messages are cached in the
sclp console buffers. In resume, all the cached messages are written to the
console. In addition to that we have an early resume function that removes
the cached messages from the suspend image.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
b3b59d3339c907b1dec3ce19f62b2a7f120d142d 25-Dec-2008 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] sclp vt220: fix compile warning

get rid of this one:

CC drivers/s390/char/sclp_vt220.o
drivers/s390/char/sclp_vt220.c:588: warning: '__sclp_vt220_flush_buffer' defined but not used

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
2332ce1a97963b7769e0c2d40492a10a124efba5 10-Oct-2008 Holger Smolinski <Holger.Smolinski@de.ibm.com> [S390] console flush on panic / reboot

The s390 console drivers use the unblank callback of the console
structure to flush the console buffer. In case of a panic or a
reboot the CPU doing the callback can block on the console i/o.
The other CPUs in the system continue to work. For panic this is
not a good idea.

Replace the unblank callback with proper panic/reboot notifier.
These get called after all but one CPU have been stopped.

Signed-off-by: Holger Smolinski <Holger.Smolinski@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
a12c53f4fa759b59654b6d5f21eb4070cd45cd54 14-Jul-2008 Martin Schwidefsky <schwidefsky@de.ibm.com> [S390] Cleanup sclp printk messages.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
ad211790c040fae3459e9c4c8cbd681ae126d2b8 14-Jul-2008 Peter Oberparleiter <peter.oberparleiter@de.ibm.com> [S390] sclp: simplify vt220 cleanup logic

Fix a number of sclp_vt220 cleanup problems:
* fix list_empty check after list_del()
* mark init-only flag as __initdata
* remove implicit dependency between slab_available() and num_pages
* straighten multiple init handling (use init count)

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
7b439d25300dc59bba76b53eb344bb9e5a1133f2 10-Jun-2008 Carsten Otte <cotte@de.ibm.com> [S390] vt220 console, initialize list head before use

This patch fixes a null pointer dereference during initialisation when no
sclp event facility is available:
sclp vt220 tty driver: could not register vt220 - sclp_register returned -5
Unable to handle kernel paging request at virtual user address 0000000000000000
Oops: 0004 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 Not tainted 2.6.26-rc3-kvm-bigiron-00968-gd939e93-dirty #30
Process swapper (pid: 0, task: 0000000000600be0, ksp: 000000000064a000)
Krnl PSW : 0400000180000000 0000000000320d8c (sclp_unregister+0x48/0x8c)
R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 EA:3
Krnl GPRS: 0000000000000000 0000000000000000 0000000000630478 0700000000649c20
0000000000000000 0000000000433060 000000000064a660 0000000002e26000
00000000006db000 0000000000000000 0000000000a78578 0000000000649b80
0000000000630dc0 000000000044fa20 0000000000320d76 0000000000649b80
Krnl Code: 0000000000320d7c: e310c0080004 lg %r1,8(%r12)
0000000000320d82: b9040032 lgr %r3,%r2
0000000000320d86: c02000187b79 larl %r2,630478
>0000000000320d8c: e34010000024 stg %r4,0(%r1)
0000000000320d92: e31040080024 stg %r1,8(%r4)
0000000000320d98: c01100200200 lgfi %r1,2097664
0000000000320d9e: e310c0080024 stg %r1,8(%r12)
0000000000320da4: c01100100100 lgfi %r1,1048832
Call Trace:
([<0000000000320d76>] sclp_unregister+0x32/0x8c)
[<00000000006657b4>] __sclp_vt220_cleanup+0xc4/0xe0
[<000000000066595c>] __sclp_vt220_init+0x18c/0x1a0
[<0000000000665aba>] sclp_vt220_con_init+0x42/0x68
[<00000000006601ca>] console_init+0x4e/0x68
[<000000000064acae>] start_kernel+0x3a2/0x4dc
[<0000000000100020>] _stext+0x20/0x80
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<000000000041f964>] _spin_lock_irqsave+0xb0/0xb4
<4>---[ end trace 31fd0ba7d8756001 ]---

The issue is caused by a list_empty() check in __sclp_vt220_cleanup, which
usually fails on non-initialized list heads that contain {NULL,NULL} instead.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
d4820e44b0ae6830b1d634e6d0a425d839388c06 30-May-2008 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] sclp_vt220: fix scheduling while atomic bug.

The driver incorrectly assumed that putchar will only be called from
schedulable process context and therefore blocked and waited if no
free output buffers where available.
Since putchar may also be called from BH context this may lead to
deadlocks.
To fix this just return the number of characters accepted and let the
upper layer handle the rest.

The console write function will busy wait (sclp_sync_wait) until a
buffer is available again.

Cc: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
9e7c9a19c1df8a7450c56c41b9c7405eca7eda07 30-Apr-2008 Alan Cox <alan@lxorguk.ukuu.org.uk> s390 tty: Prepare for put_char to return success/fail

Put the changes into the drivers first. This will still compile/work but
produce a warning if bisected so can still be debugged

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/drivers/s390/char/sclp_vt220.c
d1e23375bf5d1079cd54a1c6bc8592c42061f1e1 17-Apr-2008 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] sclp: Get rid of in_atomic() use.

Reintroduces in_interrupt() check in sclp_tty code. Add may_schedule
parameter to vt220 write function, so we can let the write function
know if it may schedule or not. So we disallow scheduling for all
console calls and may allow them for tty calls.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
fa331ffc56fb8ead0811a89e4a582bbd5f29d714 05-Mar-2008 Christian Borntraeger <borntraeger@de.ibm.com> [S390] sclp_vt220: speed up console output for interactive work

Currently an output buffer can wait up to HZ/2 until the buffer is
flushed. The wait time is noticeable in interactive tools like mc.

Change the value to HZ/20, which seems enough for interactive work.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
d082d3ce32705a92bd86c2b061d6b0827a40a5b1 19-Feb-2008 Peter Oberparleiter <peter.oberparleiter@de.ibm.com> [S390] sclp: clean up send/receive naming scheme

Make state change events adjust the correct mask by cleaning up
naming inconsistencies. Also remove chance for lockup by removing
unnecessary mask related check before reading events.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
59eb1ca7a8906412478656ba79261036261f4b76 09-Feb-2008 Christian Borntraeger <borntraeger@de.ibm.com> [S390] sclp_vt220: Fix vt220 initialization

There are two problems in the vt220 intialization:

o Currently the vt220 console looses early printk events until the
the vt220 tty is registered.
o console should work if tty_register fails

sclp_vt220_con_init calls __sclp_vt220_init and register_console.
It does not register the driver with the sclp core code via
sclp_register. That results in an sclp_send_mask=0. Therefore,
__sclp_vt220_emit will reject buffers with EIO. Unfortunately
register_console will cause the printk buffer to be sent to the
console and, therefore, every early message gets dropped. The
sclp_send_mask is set later during boot, when sclp_vt220_tty_init
calls sclp_register.

The solution is to move the sclp_register call from sclp_vt220_tty_init
to __sclp_vt220_init. This makes sure that the console is properly
registered with the sclp subsystem before the first log buffer messages
are passed to the vt220 console.

We also adopt the cleanup on error to keep the console alive if
tty_register fails.

Thanks to Peter Oberparleiter and Heiko Carstens for review and ideas
for improvement.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
e35e1fadb4585e3143fab34dd4f5070698b3305b 05-Feb-2008 Christian Borntraeger <borntraeger@de.ibm.com> [S390] sclp_tty/sclp_vt220: Fix scheduling while atomic

Under load the following bug message appeared while using sysrq-t:

BUG: scheduling while atomic: bash/3662/0x00000004
0000000000105b74 000000003ba17740 0000000000000002 0000000000000000
000000003ba177e0 000000003ba17758 000000003ba17758 0000000000105bfe
0000000000817ba8 000000003f2a5350 0000000000000000 0000000000000000
000000003ba17740 000000000000000c 000000003ba17740 000000003ba177b0
0000000000568630 0000000000105bfe 000000003ba17740 000000003ba17790
Call Trace:
([<0000000000105b74>] show_trace+0x13c/0x158)
[<0000000000105c58>] show_stack+0xc8/0xfc
[<0000000000105cbc>] dump_stack+0x30/0x40
[<000000000012a0c8>] __schedule_bug+0x84/0x94
[<000000000056234e>] schedule+0x5ea/0x970
[<0000000000477cd2>] __sclp_vt220_write+0x1f6/0x3ec
[<0000000000477f00>] sclp_vt220_con_write+0x38/0x48
[<0000000000130b4a>] __call_console_drivers+0xbe/0xd8
[<0000000000130bf0>] _call_console_drivers+0x8c/0xd0
[<0000000000130eea>] release_console_sem+0x1a6/0x2fc
[<0000000000131786>] vprintk+0x262/0x480
[<00000000001319fa>] printk+0x56/0x68
[<0000000000125aaa>] print_cfs_rq+0x45e/0x4a4
[<000000000012614e>] sched_debug_show+0x65e/0xee8
[<000000000012a8fc>] show_state_filter+0x1cc/0x1f0
[<000000000044d39c>] sysrq_handle_showstate+0x2c/0x3c
[<000000000044d1fe>] __handle_sysrq+0xae/0x18c
[<00000000002001f2>] write_sysrq_trigger+0x8a/0x90
[<00000000001f7862>] proc_reg_write+0x9a/0xc4
[<00000000001a83d4>] vfs_write+0xb8/0x174
[<00000000001a8b88>] sys_write+0x58/0x8c
[<0000000000112e7c>] sysc_noemu+0x10/0x16
[<0000020000116f68>] 0x20000116f68

The problem seems to be, that with a full console buffer, release_console_sem
disables interrupts with spin_lock_irqsave and then calls the console function
without enabling interrupts. __sclp_vt220_write checks for in_interrupt, to
decide if it can schedule. It should check for in_atomic instead.

The same is true for sclp_tty.c.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
5aaaf9f0ed11882fe7c6bc4202f78da1baa8caba 27-Jul-2007 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] Fix sclp_vt220 error handling.

Also convert to slab_is_available() as an indicator if
get_zeroed_page() will work or not.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
e62133b4ea0d85888d9883a3e1c396ea8717bc26 27-Jul-2007 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] Get rid of new section mismatch warnings.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
6d4740c89c187ee8f5ac7355c4eeffda26493d1f 27-Apr-2007 Stefan Haberland <stefan.haberland@de.ibm.com> [S390] sclp: fix coding style.

Use only capital letters for defines.

Cc: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
cd354f1ae75e6466a7e31b727faede57a1f89ca5 14-Feb-2007 Tim Schmielau <tim@physik3.uni-rostock.de> [PATCH] remove many unneeded #includes of sched.h

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>
/drivers/s390/char/sclp_vt220.c
ab14de6c37fae22911ba99f4171613e6d758050b 05-Feb-2007 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] Convert memory detection into C code.

Hopefully this will make it more maintainable and less error prone.
Code makes use of search_exception_tables(). Since it calls this
function before the kernel exeception table is sorted, there is an
early call to sort_main_extable().

This way it's easy to use the already present infrastructure of fixup
sections. Also this would allows to easily convert the rest of
head[31|64].S into C code.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
2b67fc46061b2171fb8fbb55d1ac717abd533569 05-Feb-2007 Heiko Carstens <heiko.carstens@de.ibm.com> [S390] Get rid of a lot of sparse warnings.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
/drivers/s390/char/sclp_vt220.c
b68e31d0ebbcc909d1941f9f230c9d062a3a13d3 02-Oct-2006 Jeff Dike <jdike@addtoit.com> [PATCH] const struct tty_operations

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>
/drivers/s390/char/sclp_vt220.c
6ab3d5624e172c553004ecc862bfeac16d9d68b7 30-Jun-2006 Jörn Engel <joern@wohnheim.fh-wedel.de> Remove obsolete #include <linux/config.h>

Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
/drivers/s390/char/sclp_vt220.c
33f0f88f1c51ae5c2d593d26960c760ea154c2e2 10-Jan-2006 Alan Cox <alan@lxorguk.ukuu.org.uk> [PATCH] TTY layer buffering revamp

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>
/drivers/s390/char/sclp_vt220.c
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 17-Apr-2005 Linus Torvalds <torvalds@ppc970.osdl.org> Linux-2.6.12-rc2

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!
/drivers/s390/char/sclp_vt220.c