From 2ae0f17df1cd52aafd1ab0415ea1f1dd56dc0e2a Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 24 Oct 2016 14:40:04 +0200 Subject: genetlink: use idr to track families Since generic netlink family IDs are small integers, allocated densely, IDR is an ideal match for lookups. Replace the existing hand-written hash-table with IDR for allocation and lookup. This lets the families only be written to once, during register, since the list_head can be removed and removal of a family won't cause any writes. It also slightly reduces the code size (by about 1.3k on x86-64). Signed-off-by: Johannes Berg Signed-off-by: David S. Miller --- net/netlink/genetlink.c | 271 +++++++++++++++++++----------------------------- 1 file changed, 106 insertions(+), 165 deletions(-) (limited to 'net/netlink/genetlink.c') diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index ca582ee..8565992 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -58,10 +59,8 @@ static void genl_unlock_all(void) up_write(&cb_lock); } -#define GENL_FAM_TAB_SIZE 16 -#define GENL_FAM_TAB_MASK (GENL_FAM_TAB_SIZE - 1) +static DEFINE_IDR(genl_fam_idr); -static struct list_head family_ht[GENL_FAM_TAB_SIZE]; /* * Bitmap of multicast groups that are currently in use. * @@ -86,45 +85,29 @@ static unsigned long mc_group_start = 0x3 | BIT(GENL_ID_CTRL) | static unsigned long *mc_groups = &mc_group_start; static unsigned long mc_groups_longs = 1; -static int genl_ctrl_event(int event, struct genl_family *family, +static int genl_ctrl_event(int event, const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id); -static inline unsigned int genl_family_hash(unsigned int id) +static const struct genl_family *genl_family_find_byid(unsigned int id) { - return id & GENL_FAM_TAB_MASK; + return idr_find(&genl_fam_idr, id); } -static inline struct list_head *genl_family_chain(unsigned int id) +static const struct genl_family *genl_family_find_byname(char *name) { - return &family_ht[genl_family_hash(id)]; -} - -static struct genl_family *genl_family_find_byid(unsigned int id) -{ - struct genl_family *f; + const struct genl_family *family; + unsigned int id; - list_for_each_entry(f, genl_family_chain(id), family_list) - if (f->id == id) - return f; + idr_for_each_entry(&genl_fam_idr, family, id) + if (strcmp(family->name, name) == 0) + return family; return NULL; } -static struct genl_family *genl_family_find_byname(char *name) -{ - struct genl_family *f; - int i; - - for (i = 0; i < GENL_FAM_TAB_SIZE; i++) - list_for_each_entry(f, genl_family_chain(i), family_list) - if (strcmp(f->name, name) == 0) - return f; - - return NULL; -} - -static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family) +static const struct genl_ops *genl_get_cmd(u8 cmd, + const struct genl_family *family) { int i; @@ -135,26 +118,6 @@ static const struct genl_ops *genl_get_cmd(u8 cmd, struct genl_family *family) return NULL; } -/* Of course we are going to have problems once we hit - * 2^16 alive types, but that can only happen by year 2K -*/ -static u16 genl_generate_id(void) -{ - static u16 id_gen_idx = GENL_MIN_ID; - int i; - - for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) { - if (id_gen_idx != GENL_ID_VFS_DQUOT && - id_gen_idx != GENL_ID_PMCRAID && - !genl_family_find_byid(id_gen_idx)) - return id_gen_idx; - if (++id_gen_idx > GENL_MAX_ID) - id_gen_idx = GENL_MIN_ID; - } - - return 0; -} - static int genl_allocate_reserve_groups(int n_groups, int *first_id) { unsigned long *new_groups; @@ -295,7 +258,7 @@ static int genl_validate_assign_mc_groups(struct genl_family *family) return err; } -static void genl_unregister_mc_groups(struct genl_family *family) +static void genl_unregister_mc_groups(const struct genl_family *family) { struct net *net; int i; @@ -358,6 +321,7 @@ static int genl_validate_ops(const struct genl_family *family) int genl_register_family(struct genl_family *family) { int err, i; + int start = GENL_START_ALLOC, end = GENL_MAX_ID; err = genl_validate_ops(family); if (err) @@ -370,34 +334,20 @@ int genl_register_family(struct genl_family *family) goto errout_locked; } + /* + * Sadly, a few cases need to be special-cased + * due to them having previously abused the API + * and having used their family ID also as their + * multicast group ID, so we use reserved IDs + * for both to be sure we can do that mapping. + */ if (family == &genl_ctrl) { - family->id = GENL_ID_CTRL; - } else { - u16 newid; - - /* this should be left zero in the struct */ - WARN_ON(family->id); - - /* - * Sadly, a few cases need to be special-cased - * due to them having previously abused the API - * and having used their family ID also as their - * multicast group ID, so we use reserved IDs - * for both to be sure we can do that mapping. - */ - if (strcmp(family->name, "pmcraid") == 0) - newid = GENL_ID_PMCRAID; - else if (strcmp(family->name, "VFS_DQUOT") == 0) - newid = GENL_ID_VFS_DQUOT; - else - newid = genl_generate_id(); - - if (!newid) { - err = -ENOMEM; - goto errout_locked; - } - - family->id = newid; + /* and this needs to be special for initial family lookups */ + start = end = GENL_ID_CTRL; + } else if (strcmp(family->name, "pmcraid") == 0) { + start = end = GENL_ID_PMCRAID; + } else if (strcmp(family->name, "VFS_DQUOT") == 0) { + start = end = GENL_ID_VFS_DQUOT; } if (family->maxattr && !family->parallel_ops) { @@ -410,11 +360,15 @@ int genl_register_family(struct genl_family *family) } else family->attrbuf = NULL; + family->id = idr_alloc(&genl_fam_idr, family, + start, end + 1, GFP_KERNEL); + if (!family->id) + goto errout_locked; + err = genl_validate_assign_mc_groups(family); if (err) - goto errout_locked; + goto errout_remove; - list_add_tail(&family->family_list, genl_family_chain(family->id)); genl_unlock_all(); /* send all events */ @@ -425,6 +379,8 @@ int genl_register_family(struct genl_family *family) return 0; +errout_remove: + idr_remove(&genl_fam_idr, family->id); errout_locked: genl_unlock_all(); return err; @@ -439,32 +395,29 @@ EXPORT_SYMBOL(genl_register_family); * * Returns 0 on success or a negative error code. */ -int genl_unregister_family(struct genl_family *family) +int genl_unregister_family(const struct genl_family *family) { - struct genl_family *rc; - genl_lock_all(); - list_for_each_entry(rc, genl_family_chain(family->id), family_list) { - if (family->id != rc->id || strcmp(rc->name, family->name)) - continue; + if (genl_family_find_byid(family->id)) { + genl_unlock_all(); + return -ENOENT; + } - genl_unregister_mc_groups(family); + genl_unregister_mc_groups(family); - list_del(&rc->family_list); - up_write(&cb_lock); - wait_event(genl_sk_destructing_waitq, - atomic_read(&genl_sk_destructing_cnt) == 0); - genl_unlock(); + idr_remove(&genl_fam_idr, family->id); - kfree(family->attrbuf); - genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0); - return 0; - } + up_write(&cb_lock); + wait_event(genl_sk_destructing_waitq, + atomic_read(&genl_sk_destructing_cnt) == 0); + genl_unlock(); - genl_unlock_all(); + kfree(family->attrbuf); - return -ENOENT; + genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0); + + return 0; } EXPORT_SYMBOL(genl_unregister_family); @@ -480,7 +433,7 @@ EXPORT_SYMBOL(genl_unregister_family); * Returns pointer to user specific header */ void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, - struct genl_family *family, int flags, u8 cmd) + const struct genl_family *family, int flags, u8 cmd) { struct nlmsghdr *nlh; struct genlmsghdr *hdr; @@ -539,7 +492,7 @@ static int genl_lock_done(struct netlink_callback *cb) return rc; } -static int genl_family_rcv_msg(struct genl_family *family, +static int genl_family_rcv_msg(const struct genl_family *family, struct sk_buff *skb, struct nlmsghdr *nlh) { @@ -651,7 +604,7 @@ out: static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh) { - struct genl_family *family; + const struct genl_family *family; int err; family = genl_family_find_byid(nlh->nlmsg_type); @@ -682,7 +635,7 @@ static void genl_rcv(struct sk_buff *skb) static struct genl_family genl_ctrl; -static int ctrl_fill_info(struct genl_family *family, u32 portid, u32 seq, +static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq, u32 flags, struct sk_buff *skb, u8 cmd) { void *hdr; @@ -769,7 +722,7 @@ nla_put_failure: return -EMSGSIZE; } -static int ctrl_fill_mcgrp_info(struct genl_family *family, +static int ctrl_fill_mcgrp_info(const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id, u32 portid, u32 seq, u32 flags, struct sk_buff *skb, u8 cmd) @@ -812,37 +765,30 @@ nla_put_failure: static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) { - - int i, n = 0; + int n = 0; struct genl_family *rt; struct net *net = sock_net(skb->sk); - int chains_to_skip = cb->args[0]; - int fams_to_skip = cb->args[1]; - - for (i = chains_to_skip; i < GENL_FAM_TAB_SIZE; i++) { - n = 0; - list_for_each_entry(rt, genl_family_chain(i), family_list) { - if (!rt->netnsok && !net_eq(net, &init_net)) - continue; - if (++n < fams_to_skip) - continue; - if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, - cb->nlh->nlmsg_seq, NLM_F_MULTI, - skb, CTRL_CMD_NEWFAMILY) < 0) - goto errout; - } + int fams_to_skip = cb->args[0]; + unsigned int id; - fams_to_skip = 0; - } + idr_for_each_entry(&genl_fam_idr, rt, id) { + if (!rt->netnsok && !net_eq(net, &init_net)) + continue; + + if (n++ < fams_to_skip) + continue; -errout: - cb->args[0] = i; - cb->args[1] = n; + if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, NLM_F_MULTI, + skb, CTRL_CMD_NEWFAMILY) < 0) + break; + } + cb->args[0] = n; return skb->len; } -static struct sk_buff *ctrl_build_family_msg(struct genl_family *family, +static struct sk_buff *ctrl_build_family_msg(const struct genl_family *family, u32 portid, int seq, u8 cmd) { struct sk_buff *skb; @@ -862,7 +808,7 @@ static struct sk_buff *ctrl_build_family_msg(struct genl_family *family, } static struct sk_buff * -ctrl_build_mcgrp_msg(struct genl_family *family, +ctrl_build_mcgrp_msg(const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id, u32 portid, int seq, u8 cmd) { @@ -892,7 +838,7 @@ static const struct nla_policy ctrl_policy[CTRL_ATTR_MAX+1] = { static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info) { struct sk_buff *msg; - struct genl_family *res = NULL; + const struct genl_family *res = NULL; int err = -EINVAL; if (info->attrs[CTRL_ATTR_FAMILY_ID]) { @@ -936,7 +882,7 @@ static int ctrl_getfamily(struct sk_buff *skb, struct genl_info *info) return genlmsg_reply(msg, info); } -static int genl_ctrl_event(int event, struct genl_family *family, +static int genl_ctrl_event(int event, const struct genl_family *family, const struct genl_multicast_group *grp, int grp_id) { @@ -1005,25 +951,24 @@ static struct genl_family genl_ctrl = { static int genl_bind(struct net *net, int group) { - int i, err = -ENOENT; + struct genl_family *f; + int err = -ENOENT; + unsigned int id; down_read(&cb_lock); - for (i = 0; i < GENL_FAM_TAB_SIZE; i++) { - struct genl_family *f; - - list_for_each_entry(f, genl_family_chain(i), family_list) { - if (group >= f->mcgrp_offset && - group < f->mcgrp_offset + f->n_mcgrps) { - int fam_grp = group - f->mcgrp_offset; - - if (!f->netnsok && net != &init_net) - err = -ENOENT; - else if (f->mcast_bind) - err = f->mcast_bind(net, fam_grp); - else - err = 0; - break; - } + + idr_for_each_entry(&genl_fam_idr, f, id) { + if (group >= f->mcgrp_offset && + group < f->mcgrp_offset + f->n_mcgrps) { + int fam_grp = group - f->mcgrp_offset; + + if (!f->netnsok && net != &init_net) + err = -ENOENT; + else if (f->mcast_bind) + err = f->mcast_bind(net, fam_grp); + else + err = 0; + break; } } up_read(&cb_lock); @@ -1033,21 +978,19 @@ static int genl_bind(struct net *net, int group) static void genl_unbind(struct net *net, int group) { - int i; + struct genl_family *f; + unsigned int id; down_read(&cb_lock); - for (i = 0; i < GENL_FAM_TAB_SIZE; i++) { - struct genl_family *f; - list_for_each_entry(f, genl_family_chain(i), family_list) { - if (group >= f->mcgrp_offset && - group < f->mcgrp_offset + f->n_mcgrps) { - int fam_grp = group - f->mcgrp_offset; + idr_for_each_entry(&genl_fam_idr, f, id) { + if (group >= f->mcgrp_offset && + group < f->mcgrp_offset + f->n_mcgrps) { + int fam_grp = group - f->mcgrp_offset; - if (f->mcast_unbind) - f->mcast_unbind(net, fam_grp); - break; - } + if (f->mcast_unbind) + f->mcast_unbind(net, fam_grp); + break; } } up_read(&cb_lock); @@ -1087,10 +1030,7 @@ static struct pernet_operations genl_pernet_ops = { static int __init genl_init(void) { - int i, err; - - for (i = 0; i < GENL_FAM_TAB_SIZE; i++) - INIT_LIST_HEAD(&family_ht[i]); + int err; err = genl_register_family(&genl_ctrl); if (err < 0) @@ -1118,7 +1058,7 @@ subsys_initcall(genl_init); * You cannot use this function with a family that has parallel_ops * and you can only use it within (pre/post) doit/dumpit callbacks. */ -struct nlattr **genl_family_attrbuf(struct genl_family *family) +struct nlattr **genl_family_attrbuf(const struct genl_family *family) { if (!WARN_ON(family->parallel_ops)) lockdep_assert_held(&genl_mutex); @@ -1156,8 +1096,9 @@ static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group, return err; } -int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb, - u32 portid, unsigned int group, gfp_t flags) +int genlmsg_multicast_allns(const struct genl_family *family, + struct sk_buff *skb, u32 portid, + unsigned int group, gfp_t flags) { if (WARN_ON_ONCE(group >= family->n_mcgrps)) return -EINVAL; @@ -1166,7 +1107,7 @@ int genlmsg_multicast_allns(struct genl_family *family, struct sk_buff *skb, } EXPORT_SYMBOL(genlmsg_multicast_allns); -void genl_notify(struct genl_family *family, struct sk_buff *skb, +void genl_notify(const struct genl_family *family, struct sk_buff *skb, struct genl_info *info, u32 group, gfp_t flags) { struct net *net = genl_info_net(info); -- cgit v1.1