Date: Tue, 16 Oct 2007 14:55:21 +0400
From: Alexey Dobriyan <adobriyan@sw.ru>
To: linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: sparse breakage triggered by rcu_read_lock() lockdep annotations
Message-ID: <20071016105521.GB6352@localhost.sw.ru>
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FWIW, commit 851a67b825540a8e00c0be3ee25e4627ba8b133b
aka "lockdep: annotate rcu_read_{,un}lock{,_bh}"
causes sparse to trigger internal assertion in quite a few places over
allyesconfig run.

	sparse: flow.c:805: rewrite_parent_branch: Assertion `changed' failed.

Trimmed down testcase:

	void f(unsigned long ip);
	static void g(void)
	{
	        if (1) {
	              f(({ __label__ x; x: (unsigned long)&&x; }));
	        }
	        f(({ __label__ x; x: (unsigned long)&&x; }));
	}

#0  0x4001c410 in __kernel_vsyscall ()
(gdb) bt
#0  0x4001c410 in __kernel_vsyscall ()
#1  0x40050701 in raise () from /lib/libc.so.6
#2  0x40051e38 in abort () from /lib/libc.so.6
#3  0x40049fcc in __assert_fail () from /lib/libc.so.6
#4  0x08064947 in pack_basic_blocks (ep=0x411a1c6c) at flow.c:812
#5  0x0805ffbf in linearize_symbol (sym=0x4103ec8c) at linearize.c:2154
#6  0x080492a3 in main (argc=Cannot access memory at address 0x274d) at sparse.c:266

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