From: Jeremy Kerr <jk@ozlabs.org>
Date: Tue, 26 Feb 2008 02:31:42 +0000 (+1100)
Subject: [POWERPC] spufs: fix context destruction during psmap fault
X-Git-Tag: v2.6.25-rc4~120^2~1^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d58831375d68a3bd39d5ebab9eca711fbb4ee108;p=pandora-kernel.git

[POWERPC] spufs: fix context destruction during psmap fault

We have a small window where a spu context may be destroyed while
we're servicing a page fault (from another thread) to the context's
problem state mapping.

After we up_read() the mmap_sem, it's possible that the context is
destroyed by its owning thread, and so the later references to ctx
are invalid. This can maifest as a deadlock on the (now free()-ed)
context state mutex.

This change adds a reference to the context before we release the
mmap_sem, so that the context cannot be destroyed.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
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