# git rev-parse -q --verify a9dce6679d736cb3d612af39bab9f31f8db66f9b^{commit}
a9dce6679d736cb3d612af39bab9f31f8db66f9b
already have revision, skipping fetch
# git checkout -q -f -B kisskb a9dce6679d736cb3d612af39bab9f31f8db66f9b
# git clean -qxdf
# < git log -1
# commit a9dce6679d736cb3d612af39bab9f31f8db66f9b
# Merge: f67e3fb48912 575a0ae9744d
# Author: Linus Torvalds <torvalds@linux-foundation.org>
# Date:   Sat Mar 16 13:47:14 2019 -0700
# 
#     Merge tag 'pidfd-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
#     
#     Pull pidfd system call from Christian Brauner:
#      "This introduces the ability to use file descriptors from /proc/<pid>/
#       as stable handles on struct pid. Even if a pid is recycled the handle
#       will not change. For a start these fds can be used to send signals to
#       the processes they refer to.
#     
#       With the ability to use /proc/<pid> fds as stable handles on struct
#       pid we can fix a long-standing issue where after a process has exited
#       its pid can be reused by another process. If a caller sends a signal
#       to a reused pid it will end up signaling the wrong process.
#     
#       With this patchset we enable a variety of use cases. One obvious
#       example is that we can now safely delegate an important part of
#       process management - sending signals - to processes other than the
#       parent of a given process by sending file descriptors around via scm
#       rights and not fearing that the given process will have been recycled
#       in the meantime. It also allows for easy testing whether a given
#       process is still alive or not by sending signal 0 to a pidfd which is
#       quite handy.
#     
#       There has been some interest in this feature e.g. from systems
#       management (systemd, glibc) and container managers. I have requested
#       and gotten comments from glibc to make sure that this syscall is
#       suitable for their needs as well. In the future I expect it to take on
#       most other pid-based signal syscalls. But such features are left for
#       the future once they are needed.
#     
#       This has been sitting in linux-next for quite a while and has not
#       caused any issues. It comes with selftests which verify basic
#       functionality and also test that a recycled pid cannot be signaled via
#       a pidfd.
#     
#       Jon has written about a prior version of this patchset. It should
#       cover the basic functionality since not a lot has changed since then:
#     
#           https://lwn.net/Articles/773459/
#     
#       The commit message for the syscall itself is extensively documenting
#       the syscall, including it's functionality and extensibility"
#     
#     * tag 'pidfd-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
#       selftests: add tests for pidfd_send_signal()
#       signal: add pidfd_send_signal() syscall
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux-ld --version
# < git log --format=%s --max-count=1 a9dce6679d736cb3d612af39bab9f31f8db66f9b
# < make -s -j 48 ARCH=parisc O=/kisskb/build/linus_parisc-allnoconfig_parisc CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux-  allnoconfig
# make -s -j 48 ARCH=parisc O=/kisskb/build/linus_parisc-allnoconfig_parisc CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux-  
<stdin>:1478:2: warning: #warning syscall pidfd_send_signal not implemented [-Wcpp]
<stdin>:1481:2: warning: #warning syscall io_uring_setup not implemented [-Wcpp]
<stdin>:1484:2: warning: #warning syscall io_uring_enter not implemented [-Wcpp]
<stdin>:1487:2: warning: #warning syscall io_uring_register not implemented [-Wcpp]
/kisskb/src/arch/parisc/kernel/pci-dma.c:334:12: warning: 'proc_pcxl_dma_show' defined but not used [-Wunused-function]
 static int proc_pcxl_dma_show(struct seq_file *m, void *v)
            ^~~~~~~~~~~~~~~~~~
Completed OK
# rm -rf /kisskb/build/linus_parisc-allnoconfig_parisc
# Build took: 0:00:12.996573