On 22-May-01 Matt Dillon wrote:
>
>:
>:
>:On 22-May-01 Matt Dillon wrote:
>:>:Ok, then why not let the current shmexit() stay in exit1() as a hack to
>:>:help
>:>:free memory, but add in a check in vmspace_free() as well to catch any race
>:>:conditions that may fall through the cracks? As long as we clear the shm
>:>:pointer in struct vmspace when we free it then we won't be double free'ing,
>:>:and
>:>:will always free it eventually. That is also a much simpler change. :)
>:>:Additionally, adding to the comment in exit1() clarifying that this is an
>:>:attempt to free resources as soon as possible and that the race condition
>:>:is
>:>:known and that vmspace_free() is a catch-all might be nice as well.
>:>:
>:>:--
>:>:
>:>:John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
>:>:PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
>:>
>:> It's not really good programming practice. Someone might trip over
>:> it later on.
>:
>:Then the vmspace free()ing is also bad programming practice? It's the same
>:exact algorithm used for the vmspace.
>:
>:> -Matt
>:
>:John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
>
> Huh? It doesn't look like the same algorithm to me.
In exit1() we attempt to free resources early if we can. If we lose the race,
we still clean it up in vmspace_free() called from cpu_wait(). If you check
the shm pointer and do shmexit() in vmspace_free() just as is done in
vmspace_free(), then you will catch any cases that fall through with the shm
not being free'd using the same technique currently employed in releasing the
vmspace and with a minimal amount of change to the code.
--
John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.Baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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