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genetlink: add a structure for dump state

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Whenever netlink dump uses more than 2 cb->args[] entries
code gets hard to read. We're about to add more state to
ctrl_dumppolicy() so create a structure.

Since the structure is typed and clearly named we can remove
the local fam_id variable and use ctx->fam_id directly.

v3:
 - rebase onto explicit free fix
v1:
 - s/nl_policy_dump/netlink_policy_dump_state/
 - forward declare struct netlink_policy_dump_state,
   and move from passing unsigned long to actual pointer type
 - add build bug on
 - u16 fam_id
 - s/args/ctx/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2020-10-02 14:49:55 -07:00 committed by David S. Miller
parent 66a9b9287d
commit adc848450f
3 changed files with 39 additions and 31 deletions
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11
include/net/netlink.h
View File

@ -1935,11 +1935,14 @@ void nla_get_range_unsigned(const struct nla_policy *pt,
void nla_get_range_signed(const struct nla_policy *pt, void nla_get_range_signed(const struct nla_policy *pt,
struct netlink_range_validation_signed *range); struct netlink_range_validation_signed *range);
struct netlink_policy_dump_state;
int netlink_policy_dump_start(const struct nla_policy *policy, int netlink_policy_dump_start(const struct nla_policy *policy,
unsigned int maxtype, unsigned int maxtype,
unsigned long *state); struct netlink_policy_dump_state **state);
bool netlink_policy_dump_loop(unsigned long state); bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state);
int netlink_policy_dump_write(struct sk_buff *skb, unsigned long state); int netlink_policy_dump_write(struct sk_buff *skb,
void netlink_policy_dump_free(unsigned long state); struct netlink_policy_dump_state *state);
void netlink_policy_dump_free(struct netlink_policy_dump_state *state);
#endif #endif

28
net/netlink/genetlink.c
View File

@ -1102,13 +1102,20 @@ static int genl_ctrl_event(int event, const struct genl_family *family,
return 0; return 0;
} }
struct ctrl_dump_policy_ctx {
struct netlink_policy_dump_state *state;
u16 fam_id;
};
static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb) static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
{ {
struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
const struct genl_family *rt; const struct genl_family *rt;
unsigned int fam_id = cb->args[0];
int err; int err;
if (!fam_id) { BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
if (!ctx->fam_id) {
struct nlattr *tb[CTRL_ATTR_MAX + 1]; struct nlattr *tb[CTRL_ATTR_MAX + 1];
err = genlmsg_parse(cb->nlh, &genl_ctrl, tb, err = genlmsg_parse(cb->nlh, &genl_ctrl, tb,
@ -1121,28 +1128,28 @@ static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
return -EINVAL; return -EINVAL;
if (tb[CTRL_ATTR_FAMILY_ID]) { if (tb[CTRL_ATTR_FAMILY_ID]) {
fam_id = nla_get_u16(tb[CTRL_ATTR_FAMILY_ID]); ctx->fam_id = nla_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
} else { } else {
rt = genl_family_find_byname( rt = genl_family_find_byname(
nla_data(tb[CTRL_ATTR_FAMILY_NAME])); nla_data(tb[CTRL_ATTR_FAMILY_NAME]));
if (!rt) if (!rt)
return -ENOENT; return -ENOENT;
fam_id = rt->id; ctx->fam_id = rt->id;
} }
} }
rt = genl_family_find_byid(fam_id); rt = genl_family_find_byid(ctx->fam_id);
if (!rt) if (!rt)
return -ENOENT; return -ENOENT;
if (!rt->policy) if (!rt->policy)
return -ENODATA; return -ENODATA;
err = netlink_policy_dump_start(rt->policy, rt->maxattr, &cb->args[1]); err = netlink_policy_dump_start(rt->policy, rt->maxattr, &ctx->state);
if (err) if (err)
return err; return err;
while (netlink_policy_dump_loop(cb->args[1])) { while (netlink_policy_dump_loop(ctx->state)) {
void *hdr; void *hdr;
struct nlattr *nest; struct nlattr *nest;
@ -1159,7 +1166,7 @@ static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
if (!nest) if (!nest)
goto nla_put_failure; goto nla_put_failure;
if (netlink_policy_dump_write(skb, cb->args[1])) if (netlink_policy_dump_write(skb, ctx->state))
goto nla_put_failure; goto nla_put_failure;
nla_nest_end(skb, nest); nla_nest_end(skb, nest);
@ -1172,13 +1179,14 @@ static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
break; break;
} }
cb->args[0] = fam_id;
return skb->len; return skb->len;
} }
static int ctrl_dumppolicy_done(struct netlink_callback *cb) static int ctrl_dumppolicy_done(struct netlink_callback *cb)
{ {
netlink_policy_dump_free(cb->args[1]); struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
netlink_policy_dump_free(ctx->state);
return 0; return 0;
} }

31
net/netlink/policy.c
View File

@ -14,7 +14,7 @@
#define INITIAL_POLICIES_ALLOC 10 #define INITIAL_POLICIES_ALLOC 10
struct nl_policy_dump { struct netlink_policy_dump_state {
unsigned int policy_idx; unsigned int policy_idx;
unsigned int attr_idx; unsigned int attr_idx;
unsigned int n_alloc; unsigned int n_alloc;
@ -24,11 +24,11 @@ struct nl_policy_dump {
} policies[]; } policies[];
}; };
static int add_policy(struct nl_policy_dump **statep, static int add_policy(struct netlink_policy_dump_state **statep,
const struct nla_policy *policy, const struct nla_policy *policy,
unsigned int maxtype) unsigned int maxtype)
{ {
struct nl_policy_dump *state = *statep; struct netlink_policy_dump_state *state = *statep;
unsigned int n_alloc, i; unsigned int n_alloc, i;
if (!policy || !maxtype) if (!policy || !maxtype)
@ -62,7 +62,7 @@ static int add_policy(struct nl_policy_dump **statep,
return 0; return 0;
} }
static unsigned int get_policy_idx(struct nl_policy_dump *state, static unsigned int get_policy_idx(struct netlink_policy_dump_state *state,
const struct nla_policy *policy) const struct nla_policy *policy)
{ {
unsigned int i; unsigned int i;
@ -78,13 +78,13 @@ static unsigned int get_policy_idx(struct nl_policy_dump *state,
int netlink_policy_dump_start(const struct nla_policy *policy, int netlink_policy_dump_start(const struct nla_policy *policy,
unsigned int maxtype, unsigned int maxtype,
unsigned long *_state) struct netlink_policy_dump_state **statep)
{ {
struct nl_policy_dump *state; struct netlink_policy_dump_state *state;
unsigned int policy_idx; unsigned int policy_idx;
int err; int err;
if (*_state) if (*statep)
return 0; return 0;
/* /*
@ -128,27 +128,26 @@ int netlink_policy_dump_start(const struct nla_policy *policy,
} }
} }
*_state = (unsigned long)state; *statep = state;
return 0; return 0;
} }
static bool netlink_policy_dump_finished(struct nl_policy_dump *state) static bool
netlink_policy_dump_finished(struct netlink_policy_dump_state *state)
{ {
return state->policy_idx >= state->n_alloc || return state->policy_idx >= state->n_alloc ||
!state->policies[state->policy_idx].policy; !state->policies[state->policy_idx].policy;
} }
bool netlink_policy_dump_loop(unsigned long _state) bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state)
{ {
struct nl_policy_dump *state = (void *)_state;
return !netlink_policy_dump_finished(state); return !netlink_policy_dump_finished(state);
} }
int netlink_policy_dump_write(struct sk_buff *skb, unsigned long _state) int netlink_policy_dump_write(struct sk_buff *skb,
struct netlink_policy_dump_state *state)
{ {
struct nl_policy_dump *state = (void *)_state;
const struct nla_policy *pt; const struct nla_policy *pt;
struct nlattr *policy, *attr; struct nlattr *policy, *attr;
enum netlink_attribute_type type; enum netlink_attribute_type type;
@ -306,9 +305,7 @@ int netlink_policy_dump_write(struct sk_buff *skb, unsigned long _state)
return -ENOBUFS; return -ENOBUFS;
} }
void netlink_policy_dump_free(unsigned long _state) void netlink_policy_dump_free(struct netlink_policy_dump_state *state)
{ {
struct nl_policy_dump *state = (void *)_state;
kfree(state); kfree(state);
} }