Dawson Engler <engler@csl.stanford.edu> wrote:
>
> I'm not sure if I'm missing something --- is the following a race?
>
> 2.5.62/fs/exec.c:1013:search_binary_handler:
> read_unlock(&binfmt_lock);
> retval = fn(bprm, regs);
> if (retval >= 0) {
> put_binfmt(fmt);
Don't think so.
That lock protects the global list of registered formats only. Because we
have a ref against the format's underlying module when that lock is dropped,
the module cannot be unloaded and nobody can unregister the format. Hence
the thing at *fmt is stable, and reading fmt->next after retaking the lock is
safe.
The particular piece of code you quote would be buggy if it continued
to go around the loop and again used fmt->next. But it will unconditionally
return after performing the put_binfmt() call.
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This archive was generated by hypermail 2b29 : Sun Mar 23 2003 - 22:00:42 EST