From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH] netlink: allocate group bitmaps dynamically Date: Tue, 03 Jul 2007 14:05:57 +0200 Message-ID: <468A3BA5.9050909@trash.net> References: <1179827251.7707.29.camel@localhost.localdomain> <1182178882.4063.11.camel@localhost> <1182223964.5411.76.camel@localhost.localdomain> <1182811210.6644.22.camel@johannes.berg> <1182986681.5155.55.camel@localhost> <1183121869.4089.57.camel@johannes.berg> <468504FE.9000502@trash.net> <1183122920.4089.63.camel@johannes.berg> <468507C9.2000800@trash.net> <1183124085.4089.66.camel@johannes.berg> <46850CB8.8000509@trash.net> <1183124981.4089.69.camel@johannes.berg> <46850EDE.5020804@trash.net> <1183125924.4089.73.camel@johannes.berg> <1183126739.4089.76.camel@johannes.berg> <1183129006.4089.84.camel@johannes.berg> <1183217536.5165.25.camel@localhost> <1183365821.4089.94.camel@johannes.berg> <4688F612.1060408@trash.net> <1183386883.4089.120.camel@johannes.ber g> <46890DF8.2020706@trash.net> <1183387687.4089.124.camel@johannes.berg> <1183414370.4089.141.camel@jo hannes.berg> <1183457329.3841.0.camel@johannes.berg> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: hadi@cyberus.ca, Zhang Rui , netdev@vger.kernel.org, "linux-acpi@vger" , lenb@kernel.org, Thomas Graf To: Johannes Berg Return-path: In-Reply-To: <1183457329.3841.0.camel@johannes.berg> Sender: linux-acpi-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Johannes Berg wrote: > Allow changing the number of groups for a netlink family > after it has been created. > > Signed-off-by: Johannes Berg > > --- > include/linux/netlink.h | 1 > net/netlink/af_netlink.c | 61 +++++++++++++++++++++++++++++++++++------------ > 2 files changed, 47 insertions(+), 15 deletions(-) > > --- wireless-dev.orig/net/netlink/af_netlink.c 2007-07-03 00:10:31.617889695 +0200 > +++ wireless-dev/net/netlink/af_netlink.c 2007-07-03 00:31:30.267889695 +0200 > @@ -316,8 +316,11 @@ netlink_update_listeners(struct sock *sk > > for (i = 0; i < NLGRPSZ(tbl->groups)/sizeof(unsigned long); i++) { > mask = 0; > - sk_for_each_bound(sk, node, &tbl->mc_list) > - mask |= nlk_sk(sk)->groups[i]; > + sk_for_each_bound(sk, node, &tbl->mc_list) { > + if (nlk_sk(sk)->ngroups >= > + (i + 1) * sizeof(unsigned long)) This condition implies that a socket can bind to a non-existant group, which shouldn't be possible. > + mask |= nlk_sk(sk)->groups[i]; > + } > tbl->listeners[i] = mask; > } > /* this function is only called with the netlink table "grabbed", which > @@ -555,10 +558,11 @@ netlink_update_subscriptions(struct sock > nlk->subscriptions = subscriptions; > } > > -static int netlink_alloc_groups(struct sock *sk) > +static int netlink_realloc_groups(struct sock *sk) > { > struct netlink_sock *nlk = nlk_sk(sk); > unsigned int groups; > + unsigned long *new_groups; > int err = 0; > > netlink_lock_table(); > @@ -570,9 +574,15 @@ static int netlink_alloc_groups(struct s > if (err) > return err; > > - nlk->groups = kzalloc(NLGRPSZ(groups), GFP_KERNEL); > - if (nlk->groups == NULL) > + if (nlk->ngroups >= groups) > + return 0; > + > + new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_KERNEL); > + if (new_groups == NULL) > return -ENOMEM; > + memset((char*)new_groups + NLGRPSZ(nlk->ngroups), 0, > + NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups)); > + nlk->groups = new_groups; This should probably happen with the table grabbed to avoid races with concurrent broadcasts. > @@ -1332,6 +1338,31 @@ out_sock_release: > return NULL; > } > > +int netlink_change_ngroups(int unit, unsigned int groups) > +{ > + unsigned long *listeners; > + int err = 0; > + > + netlink_table_grab(); Unfortunately that doesn't prevent races with netlink_has_listeners since its lockless (and should really stay that way). > + if (NLGRPSZ(nl_table[unit].groups) < NLGRPSZ(groups)) { > + listeners = krealloc(nl_table[unit].listeners, > + NLGRPSZ(groups), GFP_KERNEL); > + if (!listeners) { > + err = -ENOMEM; > + goto out_ungrab; > + } > + memset((char*) listeners + NLGRPSZ(nl_table[unit].groups), > + 0, NLGRPSZ(groups) - NLGRPSZ(nl_table[unit].groups)); > + nl_table[unit].listeners = listeners; > + } > + nl_table[unit].groups = groups; > + > + out_ungrab: > + netlink_table_ungrab(); > + return err; > +} > +EXPORT_SYMBOL(netlink_change_ngroups); > + > void netlink_set_nonroot(int protocol, unsigned int flags) > { > if ((unsigned int)protocol < MAX_LINKS) > --- wireless-dev.orig/include/linux/netlink.h 2007-07-03 00:09:13.047889695 +0200 > +++ wireless-dev/include/linux/netlink.h 2007-07-03 00:31:30.267889695 +0200 > @@ -161,6 +161,7 @@ extern struct sock *netlink_kernel_creat > void (*input)(struct sock *sk, int len), > struct mutex *cb_mutex, > struct module *module); > +extern int netlink_change_ngroups(int unit, unsigned int groups); > extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err); > extern int netlink_has_listeners(struct sock *sk, unsigned int group); > extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock); > >