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Date: Tue, 30 May 2006 20:00:24 +0400
From: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
To: Ingo Molnar <mingo@elte.hu>
Cc: Jiri Slaby <jirislaby@gmail.com>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, jgarzik@pobox.com, netdev@vger.kernel.org,
       alan@redhat.com
Subject: Re: [patch, -rc5-mm1] lock validator: remove softirq.c WARN_ON
Message-ID: <20060530160024.GA8987@ms2.inr.ac.ru>
References: <20060530022925.8a67b613.akpm@osdl.org> <447C261E.1090202@gmail.com> <20060530115545.GA7025@elte.hu>
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Hello!

> ok, that WARN_ON is over-eager. Fix is below:

Nevertheless, I cannot figure out what's happening here.

This local_bh_disable() is called right after schedule().
No way irqs can be disabled there. What is wrong?


static void netlink_table_grab(void)
{
        write_lock_bh(&nl_table_lock);

        if (atomic_read(&nl_table_users)) {
                DECLARE_WAITQUEUE(wait, current);

                add_wait_queue_exclusive(&nl_table_wait, &wait);
                for(;;) {
                        set_current_state(TASK_UNINTERRUPTIBLE);
                        if (atomic_read(&nl_table_users) == 0)
                                break;
                        write_unlock_bh(&nl_table_lock);
                        schedule();
                        write_lock_bh(&nl_table_lock);
                }

                __set_current_state(TASK_RUNNING);
                remove_wait_queue(&nl_table_wait, &wait);
        }
}


Alexey
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