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From: Martin Blapp <mb@imp.ch>
To: Attilio Rao <attilio@freebsd.org>
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Cc: cvs-src@freebsd.org, Martin Blapp <mbr@freebsd.org>,
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Subject: Re: cvs commit: src/sys/kern tty.c
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Hi,

> Since proctree_lock is a sx lock which uses 2 condition variables,
> they alredy drop Giant (DROP_GIANT()) before sleeping. Are you secure
> it is the right thing to do here?

Sorry, the commit message was not 100% clear. It should have been:

Retest a variable after sx_slock has been called. Giant might have been 
temporarily dropped while waiting for proctree_lock, allowing for an
intervening tty_close() that cleared tp->t_session.

Martin