Ensure tracefs is always mounted by changing our access pattern.#180
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It seems the kernel doesn't automount tracefs if we do an openat + open. This can be observed in debian9 4.9.0-13-amd64. At boot kprobe_events will not be found since it's not mounted, if you do a simple file access to it, the kernel magically mounts it underneath, but it doesn't do if we use openat + open, for reasons which I frankly don't care. So change it to issue a full open, while here improve the error message in case we just can't open any of them, also cut the variadic fmt arg since it's not used anyway and it was just bloating the code.
nicholasberlin
approved these changes
Jun 3, 2025
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It seems the kernel doesn't automount tracefs if we do an openat + open. This can be observed in debian9 4.9.0-13-amd64. At boot kprobe_events will not be found since it's not mounted, if you do a simple file access to it, the kernel magically mounts it underneath, but it doesn't do if we use openat + open, for reasons which I frankly don't care.
So change it to issue a full open, while here improve the error message in case we just can't open any of them, also cut the variadic fmt arg since it's not used anyway and it was just bloating the code.
Fixes #179