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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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7a702b4e82
Pull pidfd fixes from Christian Brauner: "Userspace tools and libraries such as strace or glibc need a cheap and reliable way to tell whether CLONE_PIDFD is supported. The easiest way is to pass an invalid fd value in the return argument, perform the syscall and verify the value in the return argument has been changed to a valid fd. However, if CLONE_PIDFD is specified we currently check if pidfd == 0 and return EINVAL if not. The check for pidfd == 0 was originally added to enable us to abuse the return argument for passing additional flags along with CLONE_PIDFD in the future. However, extending legacy clone this way would be a terrible idea and with clone3 on the horizon and the ability to reuse CLONE_DETACHED with CLONE_PIDFD there's no real need for this clutch. So remove the pidfd == 0 check and help userspace out. Also, accordig to Al, anon_inode_getfd() should only be used past the point of no failure and ksys_close() should not be used at all since it is far too easy to get wrong. Al's motto being "basically, once it's in descriptor table, it's out of your control". So Al's patch switches back to what we already had in v1 of the original patchset and uses a anon_inode_getfile() + put_user() + fd_install() sequence in the success path and a fput() + put_unused_fd() in the failure path. The other two changes should be trivial" * tag 'for-linus-20190627' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux: proc: remove useless d_is_dir() check copy_process(): don't use ksys_close() on cleanups samples: make pidfd-metadata fail gracefully on older kernels fork: don't check parent_tidptr with CLONE_PIDFD
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.