Linux-kernel mailing list archive 1999-23,: Re: Bug: Tracing recursive system calls

# Re: Bug: Tracing recursive system calls

Alan Cox (alan@lxorguk.ukuu.org.uk)
Tue, 8 Jun 1999 01:02:07 +0100 (BST)

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> syscall_trace is in the fast path?!? It only gets called when a process
> is being traced, and nobody expects traced processes to run extremely
> fast, do they?

Fast path for tracing syscalls. It would be nice to avoid a check every
trace is what I mean.

> The problem isn't that the child thread is traced, it's that the `clone'
> call itself from `kernel_thread' is traced. So one would have to clear
> the flag and then reset it in the parent.

Ok

> Besides, this doesn't suffice. There are other places in the kernel
> that make system calls (there's a `waitpid' in `request_module' for
> instance). We would need to find and change all of these and institute
> a rule for the future, or else change the inline asm definitions in
> asm/unistd.h. Either seems a lot more complex.

Good point. My solution is simple elegant and wrong.

Alan

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