From: Christian Brauner

Sent: 10 May 2024 11:55

...

For the uapi issue you describe below my take would be that we should just try, and hope that everyone's been dutifully using O_CLOEXEC. But maybe I'm biased from the gpu world, where we've been hammering it in that "O_CLOEXEC or bust" mantra since well over a decade. Really the only valid

Oh, we're very much on the same page. All new file descriptor types that I've added over the years are O_CLOEXEC by default. IOW, you need to remove O_CLOEXEC explicitly (see pidfd as an example). And imho, any new fd type that's added should just be O_CLOEXEC by default.

For fd a shell redirect creates you may want so be able to say 'this fd will have O_CLOEXEC set after the next exec'. Also (possibly) a flag that can't be cleared once set and that gets kept by dup() etc. But maybe that is excessive?

I've certainly used: # ip netns exec ns command 3</sys/class/net in order to be able to (easily) read status for interfaces in the default namespace and a specific namespace. The would be hard if the O_CLOEXEC flag had got set by default. (Especially without a shell builtin to clear it.)

David

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