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Date: Wed, 14 Apr 2010 16:36:13 +0800 From: Lai Jiangshan <laijs@...fujitsu.com> To: Eric Dumazet <eric.dumazet@...il.com> CC: David Miller <davem@...emloft.net>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, netdev <netdev@...r.kernel.org>, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH net-next-2.6] fasync: RCU locking Eric Dumazet wrote: > -void __kill_fasync(struct fasync_struct *fa, int sig, int band) > +/* > + * rcu_read_lock() is held > + */ > +static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) > { > while (fa) { > struct fown_struct * fown; > @@ -719,22 +728,19 @@ void __kill_fasync(struct fasync_struct *fa, int sig, int band) > mechanism. */ > if (!(sig == SIGURG && fown->signum == 0)) > send_sigio(fown, fa->fa_fd, band); > - fa = fa->fa_next; > + fa = rcu_dereference(fa->fa_next); > } > } > Since rcu_read_lock() protects fasync_struct *fa for us, we can access to @fa safely even fasync_remove_entry() is just called. But this patch does not ensure 'fa->fa_file is not freed' nor 'fa->fa_fd is not released', so kill_fasync_rcu() may do wrong thing if there is no other code ensure it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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