Commit Graph

6 Commits

Author SHA1 Message Date
Ed Schouten
a1215e37a4 Introduce a hooks layer for the MPSAFE TTY layer.
One of the features that prevented us from fixing some of the TTY
consumers to work once again, was an interface that allowed consumers to
do the following:

- `Sniff' incoming data, which is used by the snp(4) driver.

- Take direct control of the input and output paths of a TTY, which is
  used by ng_tty(4), ppp(4), sl(4), etc.

There's no practical advantage in committing a hooks layer without
having any consumers. In P4 there is a preliminary port of snp(4) and
thompsa@ is busy porting ng_tty(4) to this interface. I already want to
have it in the tree, because this may stimulate others to work on the
remaining modules.

Discussed with:	thompsa
Obtained from:	//depot/projects/mpsafetty/...
2008-09-22 19:25:14 +00:00
Ed Schouten
d344ffe549 Fix style(9) issue in TTY header files: document function argument names.
According to style(9), function argument names should only be omitted
for prototypes that are exported to userspace. This means we should
document the function arguments in the TTY header files, because they
are only used in userspace.

While there, change the type of the buffer argument of
ttydisc_rint_bypass() to `const void *' instead of `char *'.

Requested by:	attilio
Obtained from:	//depot/projects/mpsafetty/...
2008-09-22 18:44:09 +00:00
Christian S.J. Peron
856ebf8530 Make sure the TTY has not disappeared out from under us before calling
ttydevsw_outwakeup().  This should fix panics which occur after remote
login sessions timeout during moderate TTY activity.  An example of
where this might occur is where a pending write to the terminal is
occurring while sshd(8) is shutting down the TTY after a TCP timeout.

Submitted by:	ed
2008-09-10 20:12:10 +00:00
Ed Schouten
ffffa83b60 Use size_t to store the return value of ttydisc_getc().
The ttydisc_getc() routine obtains a read length from ttyoutq_read().
For no valid reason, the current code stores this value in an int, and
returns a size_t. There is no need to perform this useless conversion.

Obtained from:	//depot/projects/mpsafetty/...
2008-09-02 17:13:11 +00:00
Ed Schouten
a15ec0a5e4 Backport two small fixes from the MPSAFE TTY branch in Perforce:
- Implement IMAXBEL. It turned out the IMAXBEL termios switch was marked
  as supported, while it had not been implemented.

- Don't go into the high watermark when in canonical mode, no data has
  been canonicalized and the input buffer is full. This caused the
  terminal to lock up. This prevented users from pressing
  backspace/^U/etc in such cases.

  This could easily be simulated by pasting a very big amount of data in
  a shell with sh(1) in canonical mode.

Obtained from:	//depot/projects/mpsafetty/...
2008-08-29 15:02:50 +00:00
Ed Schouten
bc093719ca Integrate the new MPSAFE TTY layer to the FreeBSD operating system.
The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:

- Improved driver model:

  The old TTY layer has a driver model that is not abstract enough to
  make it friendly to use. A good example is the output path, where the
  device drivers directly access the output buffers. This means that an
  in-kernel PPP implementation must always convert network buffers into
  TTY buffers.

  If a PPP implementation would be built on top of the new TTY layer
  (still needs a hooks layer, though), it would allow the PPP
  implementation to directly hand the data to the TTY driver.

- Improved hotplugging:

  With the old TTY layer, it isn't entirely safe to destroy TTY's from
  the system. This implementation has a two-step destructing design,
  where the driver first abandons the TTY. After all threads have left
  the TTY, the TTY layer calls a routine in the driver, which can be
  used to free resources (unit numbers, etc).

  The pts(4) driver also implements this feature, which means
  posix_openpt() will now return PTY's that are created on the fly.

- Improved performance:

  One of the major improvements is the per-TTY mutex, which is expected
  to improve scalability when compared to the old Giant locking.
  Another change is the unbuffered copying to userspace, which is both
  used on TTY device nodes and PTY masters.

Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.

Obtained from:		//depot/projects/mpsafetty/...
Approved by:		philip (ex-mentor)
Discussed:		on the lists, at BSDCan, at the DevSummit
Sponsored by:		Snow B.V., the Netherlands
dcons(4) fixed by:	kan
2008-08-20 08:31:58 +00:00