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Message-ID: <c6ee5889-c41a-78e2-7656-3cbca9e4a77f@intel.com>
Date:   Wed, 19 Oct 2022 14:49:23 -0700
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Jakub Kicinski <kuba@...nel.org>, <davem@...emloft.net>,
        <johannes@...solutions.net>
CC:     <netdev@...r.kernel.org>, <edumazet@...gle.com>,
        <pabeni@...hat.com>, <jiri@...nulli.us>, <razor@...ckwall.org>,
        <nicolas.dichtel@...nd.com>, <gnault@...hat.com>, <fw@...len.de>
Subject: Re: [PATCH net-next 09/13] genetlink: add iterator for walking family
 ops



On 10/18/2022 4:07 PM, Jakub Kicinski wrote:
> Subsequent changes will expose split op structures to users,
> so walking the family ops with just an index will get harder.
> Add a structured iterator, convert the simple cases.
> Policy dumping needs more careful conversion.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
>  net/netlink/genetlink.c | 114 ++++++++++++++++++++++++++--------------
>  1 file changed, 74 insertions(+), 40 deletions(-)
> 
> diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> index 9bfb110053c7..c5fcb7b9c383 100644
> --- a/net/netlink/genetlink.c
> +++ b/net/netlink/genetlink.c
> @@ -193,6 +193,7 @@ genl_cmd_full_to_split(struct genl_split_ops *op,
>  	op->flags		= full->flags;
>  	op->validate		= full->validate;
>  
> +	/* Make sure flags include the GENL_CMD_CAP_DO / GENL_CMD_CAP_DUMP */
>  	op->flags		|= flags;
>  

This seems like it could belong in an earlier patch?

Otherwise this looks good to me.

>  	return 0;
> @@ -228,6 +229,57 @@ static void genl_get_cmd_by_index(unsigned int i,
>  		WARN_ON_ONCE(1);
>  }
>  
> +struct genl_op_iter {
> +	const struct genl_family *family;
> +	struct genl_split_ops doit;
> +	struct genl_split_ops dumpit;
> +	int i;
> +	u32 cmd;
> +	u8 flags;
> +};
> +
> +static bool
> +genl_op_iter_init(const struct genl_family *family, struct genl_op_iter *iter)
> +{
> +	iter->family = family;
> +	iter->i = 0;
> +
> +	iter->flags = 0;
> +
> +	return genl_get_cmd_cnt(iter->family);
> +}
> +
> +static bool genl_op_iter_next(struct genl_op_iter *iter)
> +{
> +	struct genl_ops op;
> +
> +	if (iter->i >= genl_get_cmd_cnt(iter->family))
> +		return false;
> +
> +	genl_get_cmd_by_index(iter->i, iter->family, &op);
> +	iter->i++;
> +
> +	genl_cmd_full_to_split(&iter->doit, iter->family, &op, GENL_CMD_CAP_DO);
> +	genl_cmd_full_to_split(&iter->dumpit, iter->family,
> +			       &op, GENL_CMD_CAP_DUMP);
> +
> +	iter->cmd = iter->doit.cmd | iter->dumpit.cmd;
> +	iter->flags = iter->doit.flags | iter->dumpit.flags;
> +
> +	return true;
> +}
> +
> +static void
> +genl_op_iter_copy(struct genl_op_iter *dst, struct genl_op_iter *src)
> +{
> +	*dst = *src;
> +}
> +
> +static unsigned int genl_op_iter_idx(struct genl_op_iter *iter)
> +{
> +	return iter->i;
> +}
> +
>  static int genl_allocate_reserve_groups(int n_groups, int *first_id)
>  {
>  	unsigned long *new_groups;
> @@ -395,23 +447,19 @@ static void genl_unregister_mc_groups(const struct genl_family *family)
>  
>  static int genl_validate_ops(const struct genl_family *family)
>  {
> -	int i, j;
> +	struct genl_op_iter i, j;
>  
>  	if (WARN_ON(family->n_ops && !family->ops) ||
>  	    WARN_ON(family->n_small_ops && !family->small_ops))
>  		return -EINVAL;
>  
> -	for (i = 0; i < genl_get_cmd_cnt(family); i++) {
> -		struct genl_ops op;
> -
> -		genl_get_cmd_by_index(i, family, &op);
> -		if (op.dumpit == NULL && op.doit == NULL)
> +	for (genl_op_iter_init(family, &i); genl_op_iter_next(&i); ) {
> +		if (!(i.flags & (GENL_CMD_CAP_DO | GENL_CMD_CAP_DUMP)))
>  			return -EINVAL;
> -		for (j = i + 1; j < genl_get_cmd_cnt(family); j++) {
> -			struct genl_ops op2;
>  
> -			genl_get_cmd_by_index(j, family, &op2);
> -			if (op.cmd == op2.cmd)
> +		genl_op_iter_copy(&j, &i);
> +		while (genl_op_iter_next(&j)) {
> +			if (i.cmd == j.cmd)
>  				return -EINVAL;
>  		}
>  	}
> @@ -891,6 +939,7 @@ static struct genl_family genl_ctrl;
>  static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
>  			  u32 flags, struct sk_buff *skb, u8 cmd)
>  {
> +	struct genl_op_iter i;
>  	void *hdr;
>  
>  	hdr = genlmsg_put(skb, portid, seq, &genl_ctrl, flags, cmd);
> @@ -904,33 +953,26 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
>  	    nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
>  		goto nla_put_failure;
>  
> -	if (genl_get_cmd_cnt(family)) {
> +	if (genl_op_iter_init(family, &i)) {
>  		struct nlattr *nla_ops;
> -		int i;
>  
>  		nla_ops = nla_nest_start_noflag(skb, CTRL_ATTR_OPS);
>  		if (nla_ops == NULL)
>  			goto nla_put_failure;
>  
> -		for (i = 0; i < genl_get_cmd_cnt(family); i++) {
> +		while (genl_op_iter_next(&i)) {
>  			struct nlattr *nest;
> -			struct genl_ops op;
>  			u32 op_flags;
>  
> -			genl_get_cmd_by_index(i, family, &op);
> -			op_flags = op.flags;
> -			if (op.dumpit)
> -				op_flags |= GENL_CMD_CAP_DUMP;
> -			if (op.doit)
> -				op_flags |= GENL_CMD_CAP_DO;
> -			if (op.policy)
> +			op_flags = i.flags;
> +			if (i.doit.policy || i.dumpit.policy)
>  				op_flags |= GENL_CMD_CAP_HASPOL;
>  
> -			nest = nla_nest_start_noflag(skb, i + 1);
> +			nest = nla_nest_start_noflag(skb, genl_op_iter_idx(&i));
>  			if (nest == NULL)
>  				goto nla_put_failure;
>  
> -			if (nla_put_u32(skb, CTRL_ATTR_OP_ID, op.cmd) ||
> +			if (nla_put_u32(skb, CTRL_ATTR_OP_ID, i.cmd) ||
>  			    nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
>  				goto nla_put_failure;
>  
> @@ -1203,8 +1245,8 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
>  	struct ctrl_dump_policy_ctx *ctx = (void *)cb->ctx;
>  	struct nlattr **tb = info->attrs;
>  	const struct genl_family *rt;
> -	struct genl_ops op;
> -	int err, i;
> +	struct genl_op_iter i;
> +	int err;
>  
>  	BUILD_BUG_ON(sizeof(*ctx) > sizeof(cb->ctx));
>  
> @@ -1259,26 +1301,18 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
>  		return 0;
>  	}
>  
> -	for (i = 0; i < genl_get_cmd_cnt(rt); i++) {
> -		struct genl_split_ops doit, dumpit;
> -
> -		genl_get_cmd_by_index(i, rt, &op);
> -
> -		genl_cmd_full_to_split(&doit, ctx->rt, &op, GENL_CMD_CAP_DO);
> -		genl_cmd_full_to_split(&dumpit, ctx->rt,
> -				       &op, GENL_CMD_CAP_DUMP);
> -
> -		if (doit.policy) {
> +	for (genl_op_iter_init(rt, &i); genl_op_iter_next(&i); ) {
> +		if (i.doit.policy) {
>  			err = netlink_policy_dump_add_policy(&ctx->state,
> -							     doit.policy,
> -							     doit.maxattr);
> +							     i.doit.policy,
> +							     i.doit.maxattr);
>  			if (err)
>  				goto err_free_state;
>  		}
> -		if (dumpit.policy) {
> +		if (i.dumpit.policy) {
>  			err = netlink_policy_dump_add_policy(&ctx->state,
> -							     dumpit.policy,
> -							     dumpit.maxattr);
> +							     i.dumpit.policy,
> +							     i.dumpit.maxattr);
>  			if (err)
>  				goto err_free_state;
>  		}

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