Jason Wang <[email protected]> writes: > On Sun, Jul 9, 2023 at 11:48 PM Bin Meng <[email protected]> wrote: >> >> On Wed, Jun 28, 2023 at 11:29 PM Bin Meng <[email protected]> wrote: >> > >> > >> > Current codes using a brute-force traversal of all file descriptors >> > do not scale on a system where the maximum number of file descriptors >> > is set to a very large value (e.g.: in a Docker container of Manjaro >> > distribution it is set to 1073741816). QEMU just looks frozen during >> > start-up. >> > >> > The close-on-exec flag (O_CLOEXEC) was introduced since Linux kernel >> > 2.6.23, FreeBSD 8.3, OpenBSD 5.0, Solaris 11. While it's true QEMU >> > doesn't need to manually close the fds for child process as the proper >> > O_CLOEXEC flag should have been set properly on files with its own >> > codes, QEMU uses a huge number of 3rd party libraries and we don't >> > trust them to reliably be using O_CLOEXEC on everything they open. >> > >> > Modern Linux and BSDs have the close_range() call we can use to do the >> > job, and on Linux we have one more way to walk through /proc/self/fd >> > to complete the task efficiently, which is what qemu_close_range() >> > does, a new API we add in util/osdep.c. >> > >> > V1 link: >> > https://lore.kernel.org/qemu-devel/[email protected]/ >> > >> > Changes in v4: >> > - add 'first > last' check logic >> > - reorder the ifdefs logic >> > - change i to unsigned int type >> > - use qemu_strtoi() instead of atoi() >> > - limit last upper value to sysconf(_SC_OPEN_MAX) - 1 >> > - call sysconf directly instead of using a variable >> > - put fd on its own line >> > >> > Changes in v3: >> > - fix win32 build failure >> > - limit the last_fd of qemu_close_range() to sysconf(_SC_OPEN_MAX) >> > >> > Changes in v2: >> > - new patch: "tests/tcg/cris: Fix the coding style" >> > - new patch: "tests/tcg/cris: Correct the off-by-one error" >> > - new patch: "util/async-teardown: Fall back to close fds one by one" >> > - new patch: "util/osdep: Introduce qemu_close_range()" >> > - new patch: "util/async-teardown: Use qemu_close_range() to close fds" >> > - Change to use qemu_close_range() to close fds for child process >> > efficiently >> > - v1 link: >> > https://lore.kernel.org/qemu-devel/[email protected]/ >> > >> > Bin Meng (4): >> > tests/tcg/cris: Fix the coding style >> > tests/tcg/cris: Correct the off-by-one error >> > util/async-teardown: Fall back to close fds one by one >> > util/osdep: Introduce qemu_close_range() >> > >> > Zhangjin Wu (2): >> > util/async-teardown: Use qemu_close_range() to close fds >> > net: tap: Use qemu_close_range() to close fds >> > >> >> Ping for 8.1? > > Queued.
There are review questions open on PATCH 4+5.
