NACK: [SRU][F:linux-bluefield][PATCH] netfilter: flowtable: Use rw sem as flow block lock

[Daniel Jurgens]

> -----Original Message-----
> From: Daniel Jurgens <danielj at nvidia.com>
> Sent: Tuesday, May 18, 2021 4:43 PM
> Subject: [SRU][F:linux-bluefield][PATCH] netfilter: flowtable: Use rw sem as
> flow block lock
> 
> From: Paul Blakey <paulb at mellanox.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1927251
> 
> Currently flow offload threads are synchronized by the flow block mutex.
> Use rw lock instead to increase flow insertion (read) concurrency.
> 
> Signed-off-by: Paul Blakey <paulb at mellanox.com>
> Reviewed-by: Oz Shlomo <ozsh at mellanox.com>
> Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org> (backported from
> commit 422c032afcf57d5e8109a54912e22ffc53d99068)

Resent with additional info about why it was backported

> Signed-off-by: Daniel Jurgens <danielj at nvidia.com>
> 
> ---
>  include/net/netfilter/nf_flow_table.h |  2 +-
>  net/netfilter/nf_flow_table_core.c    | 11 +++++------
>  net/netfilter/nf_flow_table_offload.c |  4 ++--
>  3 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/include/net/netfilter/nf_flow_table.h
> b/include/net/netfilter/nf_flow_table.h
> index 3a46b3c..e27b73f 100644
> --- a/include/net/netfilter/nf_flow_table.h
> +++ b/include/net/netfilter/nf_flow_table.h
> @@ -73,7 +73,7 @@ struct nf_flowtable {
>  	struct delayed_work		gc_work;
>  	unsigned int			flags;
>  	struct flow_block		flow_block;
> -	struct mutex			flow_block_lock; /* Guards
> flow_block */
> +	struct rw_semaphore		flow_block_lock; /* Guards
> flow_block */
>  	u32				flow_timeout;
>  	possible_net_t			net;
>  };
> diff --git a/net/netfilter/nf_flow_table_core.c
> b/net/netfilter/nf_flow_table_core.c
> index 5144e31..0c409aa 100644
> --- a/net/netfilter/nf_flow_table_core.c
> +++ b/net/netfilter/nf_flow_table_core.c
> @@ -398,7 +398,7 @@ int nf_flow_table_offload_add_cb(struct
> nf_flowtable *flow_table,
>  	struct flow_block_cb *block_cb;
>  	int err = 0;
> 
> -	mutex_lock(&flow_table->flow_block_lock);
> +	down_write(&flow_table->flow_block_lock);
>  	block_cb = flow_block_cb_lookup(block, cb, cb_priv);
>  	if (block_cb) {
>  		err = -EEXIST;
> @@ -414,7 +414,7 @@ int nf_flow_table_offload_add_cb(struct
> nf_flowtable *flow_table,
>  	list_add_tail(&block_cb->list, &block->cb_list);
> 
>  unlock:
> -	mutex_unlock(&flow_table->flow_block_lock);
> +	up_write(&flow_table->flow_block_lock);
>  	return err;
>  }
>  EXPORT_SYMBOL_GPL(nf_flow_table_offload_add_cb);
> @@ -425,13 +425,13 @@ void nf_flow_table_offload_del_cb(struct
> nf_flowtable *flow_table,
>  	struct flow_block *block = &flow_table->flow_block;
>  	struct flow_block_cb *block_cb;
> 
> -	mutex_lock(&flow_table->flow_block_lock);
> +	down_write(&flow_table->flow_block_lock);
>  	block_cb = flow_block_cb_lookup(block, cb, cb_priv);
>  	if (block_cb)
>  		list_del(&block_cb->list);
>  	else
>  		WARN_ON(true);
> -	mutex_unlock(&flow_table->flow_block_lock);
> +	up_write(&flow_table->flow_block_lock);
>  }
>  EXPORT_SYMBOL_GPL(nf_flow_table_offload_del_cb);
> 
> @@ -561,7 +561,7 @@ int nf_flow_table_init(struct nf_flowtable *flowtable)
> 
>  	INIT_DEFERRABLE_WORK(&flowtable->gc_work,
> nf_flow_offload_work_gc);
>  	flow_block_init(&flowtable->flow_block);
> -	mutex_init(&flowtable->flow_block_lock);
> +	init_rwsem(&flowtable->flow_block_lock);
> 
>  	err = rhashtable_init(&flowtable->rhashtable,
>  			      &nf_flow_offload_rhash_params); @@ -627,7
> +627,6 @@ void nf_flow_table_free(struct nf_flowtable *flow_table)
>  		nf_flow_table_iterate(flow_table, nf_flow_offload_gc_step,
>  				      flow_table);
>  	rhashtable_destroy(&flow_table->rhashtable);
> -	mutex_destroy(&flow_table->flow_block_lock);
>  }
>  EXPORT_SYMBOL_GPL(nf_flow_table_free);
> 
> diff --git a/net/netfilter/nf_flow_table_offload.c
> b/net/netfilter/nf_flow_table_offload.c
> index 26a950d..46bffaa 100644
> --- a/net/netfilter/nf_flow_table_offload.c
> +++ b/net/netfilter/nf_flow_table_offload.c
> @@ -698,7 +698,7 @@ static int nf_flow_offload_tuple(struct nf_flowtable
> *flowtable,
>  	if (cmd == FLOW_CLS_REPLACE)
>  		cls_flow.rule = flow_rule->rule;
> 
> -	mutex_lock(&flowtable->flow_block_lock);
> +	down_read(&flowtable->flow_block_lock);
>  	list_for_each_entry(block_cb, block_cb_list, list) {
>  		err = block_cb->cb(TC_SETUP_CLSFLOWER, &cls_flow,
>  				   block_cb->cb_priv);
> @@ -707,7 +707,7 @@ static int nf_flow_offload_tuple(struct nf_flowtable
> *flowtable,
> 
>  		i++;
>  	}
> -	mutex_unlock(&flowtable->flow_block_lock);
> +	up_read(&flowtable->flow_block_lock);
> 
>  	if (cmd == FLOW_CLS_STATS)
>  		memcpy(stats, &cls_flow.stats, sizeof(*stats));
> --
> 1.8.3.1