From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chris Li" Subject: Re: sparse breakage triggered by rcu_read_lock() lockdep annotations Date: Fri, 19 Oct 2007 12:44:09 -0700 Message-ID: <70318cbf0710191244v59bed9fekbef0ae1fcda22a6a@mail.gmail.com> References: <20071016105521.GB6352@localhost.sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from rv-out-0910.google.com ([209.85.198.191]:63881 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764894AbXJSToK (ORCPT ); Fri, 19 Oct 2007 15:44:10 -0400 Received: by rv-out-0910.google.com with SMTP id k20so553497rvb for ; Fri, 19 Oct 2007 12:44:09 -0700 (PDT) In-Reply-To: <20071016105521.GB6352@localhost.sw.ru> Content-Disposition: inline Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Alexey Dobriyan Cc: linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org Err, Sparse does not support the local label syntax yet. It just treats the second label "x:" as the same as the first one. Then the linearize code gets serious confused when it saw one label get define in two places. The fix seems not trivial from the first look. Chris On 10/16/07, Alexey Dobriyan wrote: > 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 > > - > To unsubscribe from this list: send the line "unsubscribe linux-sparse" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >