From owner-freebsd-current  Fri Aug  7 14:30:22 1998
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From: John Birrell  <jb@cimlogic.com.au>
Message-Id: <199808072135.HAA10923@cimlogic.com.au>
Subject: Re: memory leaks in libc
In-Reply-To: <199808071703.KAA29656@bubba.whistle.com> from Archie Cobbs at "Aug 7, 98 10:03:20 am"
To: archie@whistle.com (Archie Cobbs)
Date: Sat, 8 Aug 1998 07:35:32 +1000 (EST)
Cc: jb@cimlogic.com.au, archie@whistle.com, freebsd-current@FreeBSD.ORG,
        bde@zeta.org.au, wollman@khavrinen.lcs.mit.edu, dg@root.com
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Archie Cobbs wrote:
> Well, setenv() and unsetenv() are not thread safe as they
> currently exist. How does this look?

FWIW, I think that any proposed changes to libc should be _required_ to
be thread-safe from now on so that libc has a better chance of working
with kernel threads.

> +void
> +__env_lock(void)
> +{
> +	THREAD_LOCK();
> +}
> +
> +/*
> + * __env_unlock()
> + *
> + * Release mutex lock on the environment. Should be static.
> + */
> +void
> +__env_unlock(void)
> +{
> +	THREAD_UNLOCK();
> +}

Why add these functions? Since kernel threads require the standard libc
to be thread safe, don't expect that the calls will be optimized out.
The idea is to make the non-threaded runtime impact just a test on
the __is_threaded variable. Using the THREAD_LOCK() and THREAD_UNLOCK()
macros directly will achieve this.


-- 
John Birrell - jb@cimlogic.com.au; jb@freebsd.org http://www.cimlogic.com.au/
CIMlogic Pty Ltd, GPO Box 117A, Melbourne Vic 3001, Australia +61 418 353 137

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