Hi to all... do not know if the mailing list received this message - nobody can answer? Thanks so much giacomo ---------- Forwarded message ---------- From: Giacomo <delleceste@xxxxxxxxx> Date: 2009/2/23 Subject: linked lists, locking in softirq context To: netfilter-devel <netfilter-devel@xxxxxxxxxxxxxxx> Harald Welte's "The journey of a packet through the Linux 2.6.10 network stack" article says that packet travelling inside linux kernel 2.6 (the receive / input part) runs in softirq context. Hooking with netfilter's hooks in a kernel module, i need to read for each packet received a list of rules. Since in input and prerouting hooks the context is softirq (perhaps also in forward?), I need some read lock feature. I currently use RCU lists and, while reading lists I use READ read_lock_bh() together with list_for_each_rcu() When changing, or flushing, rules, I use WRITE spin_lock() + list_add_tail_rcu() (adding) or spin_lock() + list_for_each_entry() (for listing and then freeing with list_del_rcu() and call_rcu() ) The question is: - is the read part above correct? - do I really need _bh()? or should I use simply read_lock() ? Thanks in advance Giacomo -- Giacomo S. http://www.giacomos.it - - - - - - - - - - - - - - - - - - - - - - * Aprile 2008: iqfire-wall, un progetto open source che implementa un filtro di pacchetti di rete per Linux, e` disponibile per il download qui: http://sourceforge.net/projects/ipfire-wall * Informazioni e pagina web ufficiale: http://www.giacomos.it/iqfire/index.html - - - - - - - - - - - - - - - - - - - - - - . '' `. : :' : `. ` ' `- Debian GNU/Linux -- The power of freedom http://www.debian.org -- Giacomo S. http://www.giacomos.it - - - - - - - - - - - - - - - - - - - - - - * Aprile 2008: iqfire-wall, un progetto open source che implementa un filtro di pacchetti di rete per Linux, e` disponibile per il download qui: http://sourceforge.net/projects/ipfire-wall * Informazioni e pagina web ufficiale: http://www.giacomos.it/iqfire/index.html - - - - - - - - - - - - - - - - - - - - - - . '' `. : :' : `. ` ' `- Debian GNU/Linux -- The power of freedom http://www.debian.org -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
