Messages in this thread | | | Subject | Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC | From | Rasmus Villemoes <> | Date | Tue, 13 Oct 2020 23:49:34 +0200 |
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On 13/10/2020 23.09, Al Viro wrote: > On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote: >> + spin_lock(&cur_fds->file_lock); >> + fdt = files_fdtable(cur_fds); >> + cur_max = fdt->max_fds - 1; >> + max_fd = min(max_fd, cur_max); >> + while (fd <= max_fd) >> + __set_close_on_exec(fd++, fdt); >> + spin_unlock(&cur_fds->file_lock); > > First of all, this is an atrocious way to set all bits > in a range. What's more, you don't want to set it for *all* > bits - only for the ones present in open bitmap. It's probably > harmless at the moment, but let's not create interesting surprises > for the future.
Eh, why not? They can already be set for unallocated slots:
commit 5297908270549b734c7c2556745e2385b6d4941d Author: Mateusz Guzik <mguzik@redhat.com> Date: Tue Oct 3 12:58:14 2017 +0200
vfs: stop clearing close on exec when closing a fd
Codepaths allocating a fd always make sure the bit is set/unset depending on flags, thus clearing on close is redundant.
And while we're on that subject, yours truly suggested exactly that two years prior [1], with a follow-up [2] in 2018 to do what wasn't done in 5297908, but (still) seems like obvious micro-optimizations, given that the close_on_exec bitmap is not maintained as a subset of the open bitmap. Mind taking a look at [2]?
[1] https://lore.kernel.org/lkml/1446543679-28849-1-git-send-email-linux@rasmusvillemoes.dk/t/#u [2] https://lore.kernel.org/lkml/20181024160159.25884-1-linux@rasmusvillemoes.dk/
Rasmus
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