[v3,0/3] close_range()

Message

Christian Brauner May 24, 2019, 11:10 a.m. UTC

Hey,

This is v3 of this patchset.

This fixes a braino spotted by Oleg (/me tips proverbial hat) and splits
the implementation of close_range() into adding the actual syscall and
the wiring-up of the syscall itself as requested by Arnd. It also adds a
missing bump of __NR_compat_syscalls for arm64 that Arnd spotted.

For controversy around whether or not this is the greatest idea and api
ever I refer the avid reader to the comment section of LWN.

/* v2 */
In accordance with some comments by Linus and Al there's a
cond_resched() added to the close loop similar to what is done for
close_files().

A common helper pick_file() for __close_fd() and __close_range() has
been split out. This allows to only make a cond_resched() call when
filp_close() has been called similar to what is done in close_files().
Maybe that's not worth it. Jann mentioned that cond_resched() looks
rather cheap.

So it maybe that we could simply do:

while (fd <= max_fd) {
       __close_fd(files, fd++);
       cond_resched();
}

I also added a missing test for close_range(fd, fd, 0).

Thanks!
Christian

Christian Brauner (3):
  open: add close_range()
  arch: wire-up close_range()
  tests: add close_range() tests

 arch/alpha/kernel/syscalls/syscall.tbl        |   1 +
 arch/arm/tools/syscall.tbl                    |   1 +
 arch/arm64/include/asm/unistd.h               |   2 +-
 arch/arm64/include/asm/unistd32.h             |   2 +
 arch/ia64/kernel/syscalls/syscall.tbl         |   1 +
 arch/m68k/kernel/syscalls/syscall.tbl         |   1 +
 arch/microblaze/kernel/syscalls/syscall.tbl   |   1 +
 arch/mips/kernel/syscalls/syscall_n32.tbl     |   1 +
 arch/mips/kernel/syscalls/syscall_n64.tbl     |   1 +
 arch/mips/kernel/syscalls/syscall_o32.tbl     |   1 +
 arch/parisc/kernel/syscalls/syscall.tbl       |   1 +
 arch/powerpc/kernel/syscalls/syscall.tbl      |   1 +
 arch/s390/kernel/syscalls/syscall.tbl         |   1 +
 arch/sh/kernel/syscalls/syscall.tbl           |   1 +
 arch/sparc/kernel/syscalls/syscall.tbl        |   1 +
 arch/x86/entry/syscalls/syscall_32.tbl        |   1 +
 arch/x86/entry/syscalls/syscall_64.tbl        |   1 +
 arch/xtensa/kernel/syscalls/syscall.tbl       |   1 +
 fs/file.c                                     |  62 +++++++-
 fs/open.c                                     |  20 +++
 include/linux/fdtable.h                       |   2 +
 include/linux/syscalls.h                      |   2 +
 include/uapi/asm-generic/unistd.h             |   4 +-
 tools/testing/selftests/Makefile              |   1 +
 tools/testing/selftests/core/.gitignore       |   1 +
 tools/testing/selftests/core/Makefile         |   6 +
 .../testing/selftests/core/close_range_test.c | 142 ++++++++++++++++++
 27 files changed, 250 insertions(+), 10 deletions(-)
 create mode 100644 tools/testing/selftests/core/.gitignore
 create mode 100644 tools/testing/selftests/core/Makefile
 create mode 100644 tools/testing/selftests/core/close_range_test.c