57 Commits

Author SHA1 Message Date
David Howells
c73be61ced pipe: Add general notification queue support
Make it possible to have a general notification queue built on top of a
standard pipe.  Notifications are 'spliced' into the pipe and then read
out.  splice(), vmsplice() and sendfile() are forbidden on pipes used for
notifications as post_one_notification() cannot take pipe->mutex.  This
means that notifications could be posted in between individual pipe
buffers, making iov_iter_revert() difficult to effect.

The way the notification queue is used is:

 (1) An application opens a pipe with a special flag and indicates the
     number of messages it wishes to be able to queue at once (this can
     only be set once):

	pipe2(fds, O_NOTIFICATION_PIPE);
	ioctl(fds[0], IOC_WATCH_QUEUE_SET_SIZE, queue_depth);

 (2) The application then uses poll() and read() as normal to extract data
     from the pipe.  read() will return multiple notifications if the
     buffer is big enough, but it will not split a notification across
     buffers - rather it will return a short read or EMSGSIZE.

     Notification messages include a length in the header so that the
     caller can split them up.

Each message has a header that describes it:

	struct watch_notification {
		__u32	type:24;
		__u32	subtype:8;
		__u32	info;
	};

The type indicates the source (eg. mount tree changes, superblock events,
keyring changes, block layer events) and the subtype indicates the event
type (eg. mount, unmount; EIO, EDQUOT; link, unlink).  The info field
indicates a number of things, including the entry length, an ID assigned to
a watchpoint contributing to this buffer and type-specific flags.

Supplementary data, such as the key ID that generated an event, can be
attached in additional slots.  The maximum message size is 127 bytes.
Messages may not be padded or aligned, so there is no guarantee, for
example, that the notification type will be on a 4-byte bounary.

Signed-off-by: David Howells <dhowells@redhat.com>
2020-05-19 15:08:24 +01:00
Oded Gabbay
d8e8ff1fe3 docs: ioctl-number.rst: add habanalabs driver IOCTL
Habanalabs driver in misc exposes several IOCTLs to userspace. Document the
letter and IOCTLs number range in ioctl-number.rst.

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20200418174132.10597-1-oded.gabbay@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-20 17:01:53 -06:00
Haren Myneni
45f25a79fe powerpc/vas: Define VAS_TX_WIN_OPEN ioctl API
Define the VAS_TX_WIN_OPEN ioctl interface for NX GZIP access
from user space. This interface is used to open GZIP send window and
mmap region which can be used by userspace to send requests to NX
directly with copy/paste instructions.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587114065.2275.1106.camel@hbabu-laptop
2020-04-20 16:53:13 +10:00
Alexandre Belloni
473da2f0d8 docs: userspace: ioctl-number: remove mc146818rtc conflict
In 2.3.43pre2, the RTC ioctls definitions were actually moved from
linux/mc146818rtc.h to linux/rtc.h

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200209203304.66004-1-alexandre.belloni@bootlin.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-13 11:42:02 -07:00
Arnd Bergmann
f10870b05d staging: remove isdn capi drivers
As described in drivers/staging/isdn/TODO, the drivers are all
assumed to be unmaintained and unused now, with gigaset being the
last one to stop being maintained after Paul Bolle lost access
to an ISDN network.

The CAPI subsystem remains for now, as it is still required by
bluetooth/cmtp.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20191210210455.3475361-1-arnd@arndb.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-11 09:11:29 +01:00
Linus Torvalds
937d6eefc7 Here's the main documentation changes for 5.5:
- Various kerneldoc script enhancements.
 
  - More RST conversions; those are slowing down as we run out of things to
    convert, but we're a ways from done still.
 
  - Dan's "maintainer profile entry" work landed at last.  Now we just need
    to get maintainers to fill in the profiles...
 
  - A reworking of the parallel build setup to work better with a variety of
    systems (and to not take over huge systems entirely in particular).
 
  - The MAINTAINERS file is now converted to RST during the build.
    Hopefully nobody ever tries to print this thing, or they will need to
    load a lot of paper.
 
  - A script and documentation making it easy for maintainers to add Link:
    tags at commit time.
 
 Also included is the removal of a bunch of spurious CR characters.
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Merge tag 'docs-5.5a' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:
 "Here are the main documentation changes for 5.5:

   - Various kerneldoc script enhancements.

   - More RST conversions; those are slowing down as we run out of
     things to convert, but we're a ways from done still.

   - Dan's "maintainer profile entry" work landed at last. Now we just
     need to get maintainers to fill in the profiles...

   - A reworking of the parallel build setup to work better with a
     variety of systems (and to not take over huge systems entirely in
     particular).

   - The MAINTAINERS file is now converted to RST during the build.
     Hopefully nobody ever tries to print this thing, or they will need
     to load a lot of paper.

   - A script and documentation making it easy for maintainers to add
     Link: tags at commit time.

  Also included is the removal of a bunch of spurious CR characters"

* tag 'docs-5.5a' of git://git.lwn.net/linux: (91 commits)
  docs: remove a bunch of stray CRs
  docs: fix up the maintainer profile document
  libnvdimm, MAINTAINERS: Maintainer Entry Profile
  Maintainer Handbook: Maintainer Entry Profile
  MAINTAINERS: Reclaim the P: tag for Maintainer Entry Profile
  docs, parallelism: Rearrange how jobserver reservations are made
  docs, parallelism: Do not leak blocking mode to other readers
  docs, parallelism: Fix failure path and add comment
  Documentation: Remove bootmem_debug from kernel-parameters.txt
  Documentation: security: core.rst: fix warnings
  Documentation/process/howto/kokr: Update for 4.x -> 5.x versioning
  Documentation/translation: Use Korean for Korean translation title
  docs/memory-barriers.txt: Remove remaining references to mmiowb()
  docs/memory-barriers.txt/kokr: Update I/O section to be clearer about CPU vs thread
  docs/memory-barriers.txt/kokr: Fix style, spacing and grammar in I/O section
  Documentation/kokr: Kill all references to mmiowb()
  docs/memory-barriers.txt/kokr: Rewrite "KERNEL I/O BARRIER EFFECTS" section
  docs: Add initial documentation for devfreq
  Documentation: Document how to get links with git am
  docs: Add request_irq() documentation
  ...
2019-12-02 11:51:02 -08:00
Jonathan Corbet
049500715e docs: Move the user-space ioctl() docs to userspace-api
This is strictly user-space material at this point, so put it with the
other user-space API documentation.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-10-10 11:21:54 -06:00