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Masatake YAMATO authored
Finding endpoints of an IPC channel is one of essential task to
understand how a user program works.  Procfs and netlink socket provide
enough hints to find endpoints for IPC channels like pipes, unix
sockets, and pseudo terminals.  However, there is no simple way to find
endpoints for an eventfd file from userland.  An inode number doesn't
hint.  Unlike pipe, all eventfd files share the same inode object.

To provide the way to find endpoints of an eventfd file, this patch adds
"eventfd-id" field to /proc/PID/fdinfo of eventfd as identifier.
Integers managed by an IDA are used as ids.

A tool like lsof can utilize the information to print endpoints.

Link: http://lkml.kernel.org/r/20190327181823.20222-1-yamato@redhat.com


Signed-off-by: default avatarMasatake YAMATO <yamato@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
b556db17
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.