Re: Losing BPF's

[Guy Harris <guy () alum mit edu>]

maneeshs wrote:

> There seems to be a race condition in the above code, the check for the 
> descriptor being free and the call to D_GET to mark the descriptor as 
> being used is not atomic. So two closely spaced calls to bpfopen could 
> cause bpf to use the same device twice ?

Yes, if, in OpenBSD, either

        1) you're on a multi-processor machine

or

        2) the kernel is preemptible

and there's no big lock around the kernel or around opens or around 
special-file opens or something else above the BPF open routine.

FreeBSD has a single global BPF mutex (bpf_mtx).
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