Re: [PATCH net-next v3 1/3] net: ti: icssm-prueth: Adds helper functions to configure and maintain FDB

[Parvathi Pudi <parvathi@couthit.com>]

Hi,

>> +void icssm_prueth_sw_fdb_tbl_init(struct prueth *prueth)
>> +{
>> +	struct fdb_tbl *t = prueth->fdb_tbl;
>> +
>> +	t->index_a = (struct fdb_index_array_t *)((__force const void *)
>> +			prueth->mem[V2_1_FDB_TBL_LOC].va +
>> +			V2_1_FDB_TBL_OFFSET);
> 
> We have
> 
>> +#define V2_1_FDB_TBL_LOC          PRUETH_MEM_SHARED_RAM
> 
> and existing code like:
> 
> void __iomem *sram_base = prueth->mem[PRUETH_MEM_SHARED_RAM].va;
> 
> so it seems like
> 
> t->index_a = sram_base + V2_1_FDB_TBL_OFFSET;
> 
> with no needs for any casts, since sram_base is a void * so can be
> assigned to any pointer type.
> 
> And there are lots of cascading defines like:
> 
> /* 4 queue descriptors for port 0 (host receive). 32 bytes */
> #define HOST_QUEUE_DESC_OFFSET          (HOST_QUEUE_SIZE_ADDR + 16)
> 
> /* table offset for queue size:
> * 3 ports * 4 Queues * 1 byte offset = 12 bytes
> */
> #define HOST_QUEUE_SIZE_ADDR            (HOST_QUEUE_OFFSET_ADDR + 8)
> /* table offset for queue:
> * 4 Queues * 2 byte offset = 8 bytes
> */
> #define HOST_QUEUE_OFFSET_ADDR          (HOST_QUEUE_DESCRIPTOR_OFFSET_ADDR + 8)
> /* table offset for Host queue descriptors:
> * 1 ports * 4 Queues * 2 byte offset = 8 bytes
> */
> #define HOST_QUEUE_DESCRIPTOR_OFFSET_ADDR       (HOST_Q4_RX_CONTEXT_OFFSET + 8)
> 
> allowing code like:
> 
>	sram = sram_base + HOST_QUEUE_SIZE_ADDR;
>	sram = sram_base + HOST_Q1_RX_CONTEXT_OFFSET;
>	sram = sram_base + HOST_QUEUE_OFFSET_ADDR;
>	sram = sram_base + HOST_QUEUE_DESCRIPTOR_OFFSET_ADDR;
>	sram = sram_base + HOST_QUEUE_DESC_OFFSET;
> 

Sure, we will check the feasibility and come back.


>> +	t->mac_tbl_a = (struct fdb_mac_tbl_array_t *)((__force const void *)
>> +			t->index_a + FDB_INDEX_TBL_MAX_ENTRIES *
>> +			sizeof(struct fdb_index_tbl_entry_t));
> 
> So i think this could follow the same pattern, also allowing some of
> these casts to be removed.
> 
> I just don't like casts, they suggest bad design.
> 

Sure, we will check the feasibility and come back.

>> +static u8 icssm_pru_lock_done(struct fdb_tbl *fdb_tbl)
>> +{
>> +	return readb((u8 __iomem *)&fdb_tbl->locks->pru_locks);
> 
> And maybe the __iomem attribute can be added to struct, either per
> member, or at the top level? It is all iomem, so we want sparse to be
> able to check all accesses.
> 

Sure, we will check the feasibility and come back.

>> +static int icssm_prueth_sw_fdb_spin_lock(struct fdb_tbl *fdb_tbl)
>> +{
>> +	u8 done;
>> +	int ret;
>> +
>> +	/* Take the host lock */
>> +	writeb(1, (u8 __iomem *)&fdb_tbl->locks->host_lock);
>> +
>> +	/* Wait for the PRUs to release their locks */
>> +	ret = read_poll_timeout(icssm_pru_lock_done, done, done == 0,
>> +				1, 10, false, fdb_tbl);
>> +	if (ret)
>> +		return -ETIMEDOUT;
>> +
>> +	return 0;
> 
> Documentation says:
> 
> * Returns: 0 on success and -ETIMEDOUT upon a timeout.
> 
> So no need for the if statement.
> 
> 

Sure, we will address this in the next version.

>> +static s16
>> +icssm_prueth_sw_fdb_search(struct fdb_mac_tbl_array_t *mac_tbl,
>> +			   struct fdb_index_tbl_entry_t *bucket_info,
>> +			   const u8 *mac)
>> +{
>> +	u8 mac_tbl_idx = bucket_info->bucket_idx;
>> +	int i;
>> +
>> +	for (i = 0; i < bucket_info->bucket_entries; i++, mac_tbl_idx++) {
>> +		if (ether_addr_equal(mac,
>> +				     mac_tbl->mac_tbl_entry[mac_tbl_idx].mac))
>> +			return mac_tbl_idx;
>> +	}
>> +
>> +	return -ENODATA;
> 
> It is traditional to return errno in an int. But i don't see why a s16
> cannot be used.
> 

For now we will modify the return type to integer at all applicable places.


>> +icssm_prueth_sw_fdb_find_bucket_insert_point(struct fdb_tbl *fdb,
>> +					     struct fdb_index_tbl_entry_t
>> +					     *bkt_info,
>> +					     const u8 *mac, const u8 port)
>> +{
>> +	struct fdb_mac_tbl_array_t *mac_tbl = fdb->mac_tbl_a;
>> +	struct fdb_mac_tbl_entry_t *e;
>> +	u8 mac_tbl_idx;
>> +	int i, ret;
>> +	s8 cmp;
>> +
>> +	mac_tbl_idx = bkt_info->bucket_idx;
>> +
>> +	for (i = 0; i < bkt_info->bucket_entries; i++, mac_tbl_idx++) {
>> +		e = &mac_tbl->mac_tbl_entry[mac_tbl_idx];
>> +		cmp = memcmp(mac, e->mac, ETH_ALEN);
>> +		if (cmp < 0) {
>> +			return mac_tbl_idx;
>> +		} else if (cmp == 0) {
>> +			if (e->port != port) {
>> +				/* MAC is already in FDB, only port is
>> +				 * different. So just update the port.
>> +				 * Note: total_entries and bucket_entries
>> +				 * remain the same.
>> +				 */
>> +				ret = icssm_prueth_sw_fdb_spin_lock(fdb);
>> +				if (ret) {
>> +					pr_err("PRU lock timeout\n");
>> +					return -ETIMEDOUT;
>> +				}
> 
> icssm_prueth_sw_fdb_spin_lock() returns an errno. Don't replace it.
> 
> Also, pr_err() is bad practice and probably checkpatch is telling you
> this. Ideally you want to indicate which device has an error, so you
> should be using dev_err(), or maybe netdev_err().
> 

We’ll return the “ret” value and replace the pr_err() with netdev_err()
so the message shows which device had the error.

>> +	if (left > 0) {
>> +		hash_prev =
>> +			icssm_prueth_sw_fdb_hash
>> +			(FDB_MAC_TBL_ENTRY(left - 1)->mac);
>> +	}
> 
>> +		empty_slot_idx =
>> +			icssm_prueth_sw_fdb_check_empty_slot_right(mt, mti);
> 
> There are a couple of odd indentations like this. I wounder if it
> makes sense to shorten the prefix? Do you really need all of
> icssm_prueth_sw_fdb_ ?
> 
> 	Andrew

The long prefix is to keep the functions names clear, but we will shorten
it and fix the indentations.


Thanks and Regards,
Parvathi.