# 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/arcompact-buildroot-2015.08.1/bin/arc-buildroot-linux-uclibc-gcc --version
# < /opt/cross/kisskb/arcompact-buildroot-2015.08.1/bin/arc-buildroot-linux-uclibc-ld --version
# < git log --format=%s --max-count=1 a9dce6679d736cb3d612af39bab9f31f8db66f9b
# < make -s -j 48 ARCH=arc O=/kisskb/build/linus_axs101_defconfig_arcompact CROSS_COMPILE=/opt/cross/kisskb/arcompact-buildroot-2015.08.1/bin/arc-buildroot-linux-uclibc-  axs101_defconfig
# Added to kconfig CONFIG_INITRAMFS_SOURCE=""
# yes \n | make -s -j 48 ARCH=arc O=/kisskb/build/linus_axs101_defconfig_arcompact CROSS_COMPILE=/opt/cross/kisskb/arcompact-buildroot-2015.08.1/bin/arc-buildroot-linux-uclibc-  oldconfig
yes: standard output: Broken pipe
# make -s -j 48 ARCH=arc O=/kisskb/build/linus_axs101_defconfig_arcompact CROSS_COMPILE=/opt/cross/kisskb/arcompact-buildroot-2015.08.1/bin/arc-buildroot-linux-uclibc-  
/kisskb/src/arch/arc/boot/dts/axs10x_mb.dtsi:221.15-225.6: Warning (i2c_bus_reg): /axs10x_mb/i2c@0x1f000/eeprom@0x54: I2C bus unit address format error, expected "54"
/kisskb/src/arch/arc/boot/dts/axs10x_mb.dtsi:227.15-231.6: Warning (i2c_bus_reg): /axs10x_mb/i2c@0x1f000/eeprom@0x57: I2C bus unit address format error, expected "57"
/kisskb/src/arch/arc/mm/tlb.c: In function 'do_tlb_overlap_fault':
/kisskb/src/arch/arc/mm/tlb.c:914:2: warning: variable length array 'pd0' is used [-Wvla]
  unsigned int pd0[mmu->ways];
  ^
In file included from /kisskb/src/arch/arc/include/asm/atomic.h:16:0,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/asm-generic/bitops/lock.h:5,
                 from /kisskb/src/arch/arc/include/asm/bitops.h:429,
                 from /kisskb/src/include/linux/bitops.h:19,
                 from /kisskb/src/include/linux/kernel.h:12,
                 from /kisskb/src/include/linux/list.h:9,
                 from /kisskb/src/include/linux/module.h:9,
                 from /kisskb/src/net/core/filter.c:24:
/kisskb/src/net/core/filter.c: In function 'bpf_clear_redirect_map':
/kisskb/src/arch/arc/include/asm/cmpxchg.h:95:29: warning: value computed is not used [-Wunused-value]
 #define cmpxchg(ptr, o, n) ((typeof(*(ptr)))__cmpxchg((ptr), \
                             ^
/kisskb/src/net/core/filter.c:3481:4: note: in expansion of macro 'cmpxchg'
    cmpxchg(&ri->map, map, NULL);
    ^
/kisskb/src/net/ipv4/tcp_input.c: In function 'tcp_data_queue':
/kisskb/src/net/ipv4/tcp_input.c:4315:49: warning: array subscript is above array bounds [-Warray-bounds]
     tp->selective_acks[i-1] = tp->selective_acks[i];
                                                 ^
In file included from /kisskb/src/arch/arc/include/asm/atomic.h:16:0,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/asm-generic/bitops/lock.h:5,
                 from /kisskb/src/arch/arc/include/asm/bitops.h:429,
                 from /kisskb/src/include/linux/bitops.h:19,
                 from /kisskb/src/include/linux/kernel.h:12,
                 from /kisskb/src/include/linux/list.h:9,
                 from /kisskb/src/include/linux/wait.h:7,
                 from /kisskb/src/include/linux/wait_bit.h:8,
                 from /kisskb/src/include/linux/fs.h:6,
                 from /kisskb/src/fs/nfs/nfs3acl.c:2:
/kisskb/src/fs/nfs/nfs3acl.c: In function 'nfs3_abort_get_acl':
/kisskb/src/arch/arc/include/asm/cmpxchg.h:95:29: warning: value computed is not used [-Wunused-value]
 #define cmpxchg(ptr, o, n) ((typeof(*(ptr)))__cmpxchg((ptr), \
                             ^
/kisskb/src/fs/nfs/nfs3acl.c:44:2: note: in expansion of macro 'cmpxchg'
  cmpxchg(p, sentinel, ACL_NOT_CACHED);
  ^
/kisskb/src/fs/fs_parser.c: In function 'fs_validate_description':
/kisskb/src/fs/fs_parser.c:413:6: warning: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'int' [-Wformat=]
      pr_err("VALIDATE %s: e[%lu] enum val for %s\n",
      ^
In file included from /kisskb/src/arch/arc/include/asm/atomic.h:16:0,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/include/asm-generic/bitops/lock.h:5,
                 from /kisskb/src/arch/arc/include/asm/bitops.h:429,
                 from /kisskb/src/include/linux/bitops.h:19,
                 from /kisskb/src/include/linux/kernel.h:12,
                 from /kisskb/src/fs/posix_acl.c:13:
/kisskb/src/fs/posix_acl.c: In function 'get_acl':
/kisskb/src/arch/arc/include/asm/cmpxchg.h:95:29: warning: value computed is not used [-Wunused-value]
 #define cmpxchg(ptr, o, n) ((typeof(*(ptr)))__cmpxchg((ptr), \
                             ^
/kisskb/src/fs/posix_acl.c:147:3: note: in expansion of macro 'cmpxchg'
   cmpxchg(p, sentinel, ACL_NOT_CACHED);
   ^
Completed OK
# rm -rf /kisskb/build/linus_axs101_defconfig_arcompact
# Build took: 0:00:58.831453