From: Haavard Skinnemoen Date: Wed, 27 Feb 2008 13:04:29 +0000 (+0100) Subject: avr32: Fix OCD refcounting bug X-Git-Tag: v2.6.25-rc4~143^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=325d6f5593b40b5a48cf4ade74c01681f2ff6044;p=pandora-kernel.git avr32: Fix OCD refcounting bug Iff the parent has TIF_DEBUG set, _and_ clone_flags includes CLONE_PTRACE we should set the TIF_DEBUG flag for the child and increment the ocd refcount. Otherwise, the TIF_DEBUG flag must be unset. Currently, the child inherits TIF_DEBUG from the parent before copy_thread is called, so TIF_DEBUG may be already be set before we determine whether the child is supposed to inherit debugging capabilities from the parent or not. This means that ocd_enable() won't increment the refcount, because TIF_DEBUG is already set, and that TIF_DEBUG will be set for processes that aren't being debugged. This leads to a refcounting asymmetry, which may show up as ------------[ cut here ]------------ Badness at arch/avr32/kernel/ocd.c:73 PC is at ocd_disable+0x34/0x60 LR is at put_lock_stats+0xa/0x20 as reported by David Brownell. Happens when strace'ing a process that forks a new child process, e.g. "strace mount -tjffs2 mtd1 /mnt", and subsequently killing the child process (e.g. "umount /mnt".) Signed-off-by: Haavard Skinnemoen --- Reading git-diff-tree failed