Re: [PATCH 3/4] myri10ge - Driver core

Brice Goglin
2006-05-19T23:16:20Z

Arnd Bergmann wrote:
>> +static int myri10ge_open(struct net_device *dev)
>>
>
> This function is too long to read easily.
>

Ok we have split it a little bit.

>> + /* allocate the host shadow rings */
>> +
>> + bytes = 8 + (MYRI10GE_MCP_ETHER_MAX_SEND_DESC_TSO + 4)
>> + * sizeof(*mgp->tx.req_list);
>> + mgp->tx.req_bytes = kmalloc(bytes, GFP_KERNEL);
>> + if (mgp->tx.req_bytes == NULL)
>> + goto abort_with_nothing;
>> + memset(mgp->tx.req_bytes, 0, bytes);
>> +
>> + /* ensure req_list entries are aligned to 8 bytes */
>> + mgp->tx.req_list = (struct mcp_kreq_ether_send *)
>> + ALIGN((unsigned long)mgp->tx.req_bytes, 8);
>> +
>> + bytes = rx_ring_entries * sizeof(*mgp->rx_small.shadow);
>> + mgp->rx_small.shadow = kmalloc(bytes, GFP_KERNEL);
>> + if (mgp->rx_small.shadow == NULL)
>> + goto abort_with_tx_req_bytes;
>> + memset(mgp->rx_small.shadow, 0, bytes);
>> +
>> + bytes = rx_ring_entries * sizeof(*mgp->rx_big.shadow);
>> + mgp->rx_big.shadow = kmalloc(bytes, GFP_KERNEL);
>> + if (mgp->rx_big.shadow == NULL)
>> + goto abort_with_rx_small_shadow;
>> + memset(mgp->rx_big.shadow, 0, bytes);
>> +
>> + /* allocate the host info rings */
>> +
>> + bytes = tx_ring_entries * sizeof(*mgp->tx.info);
>> + mgp->tx.info = kmalloc(bytes, GFP_KERNEL);
>> + if (mgp->tx.info == NULL)
>> + goto abort_with_rx_big_shadow;
>> + memset(mgp->tx.info, 0, bytes);
>> +
>> + bytes = rx_ring_entries * sizeof(*mgp->rx_small.info);
>> + mgp->rx_small.info = kmalloc(bytes, GFP_KERNEL);
>> + if (mgp->rx_small.info == NULL)
>> + goto abort_with_tx_info;
>> + memset(mgp->rx_small.info, 0, bytes);
>> +
>> + bytes = rx_ring_entries * sizeof(*mgp->rx_big.info);
>> + mgp->rx_big.info = kmalloc(bytes, GFP_KERNEL);
>> + if (mgp->rx_big.info == NULL)
>> + goto abort_with_rx_small_info;
>> + memset(mgp->rx_big.info, 0, bytes);
>> +
>>
>
> Can you do all these allocations at once? Maybe you can even
> move them into the size passed to alloc_etherdev.
>

They are different things conceptually, so we prefer to allocate
them separately.

> If you need separate allocations, using kzalloc simplifies
> your code.
>

Right, will do.

>> + /* Break the SKB or Fragment up into pieces which
>> + * do not cross mgp->tx.boundary */
>> + low = MYRI10GE_LOWPART_TO_U32(bus);
>> + high_swapped = htonl(MYRI10GE_HIGHPART_TO_U32(bus));
>> + while (len) {
>> + u8 flags_next;
>> + int cum_len_next;
>> +
>> + if (unlikely(count == max_segments))
>> + goto abort_linearize;
>> +
>> + boundary = (low + tx->boundary) & ~(tx->boundary - 1);
>> + seglen = boundary - low;
>> + if (seglen > len)
>> + seglen = len;
>> + flags_next = flags & ~MYRI10GE_MCP_ETHER_FLAGS_FIRST;
>> + cum_len_next = cum_len + seglen;
>> +#ifdef NETIF_F_TSO
>> + if (mss) { /* TSO */
>> + (req - rdma_count)->rdma_count = rdma_count + 1;
>> +
>> + if (likely(cum_len >= 0)) { /* payload */
>> + int next_is_first, chop;
>> +
>> + chop = (cum_len_next > mss);
>> + cum_len_next = cum_len_next % mss;
>> + next_is_first = (cum_len_next == 0);
>> + flags |= chop *
>> + MYRI10GE_MCP_ETHER_FLAGS_TSO_CHOP;
>> + flags_next |= next_is_first *
>> + MYRI10GE_MCP_ETHER_FLAGS_FIRST;
>> + rdma_count |= -(chop | next_is_first);
>> + rdma_count += chop & !next_is_first;
>> + } else if (likely(cum_len_next >= 0)) { /* header ends */
>> + int small;
>> +
>> + rdma_count = -1;
>> + cum_len_next = 0;
>> + seglen = -cum_len;
>> + small =
>> + (mss <=
>> + MYRI10GE_MCP_ETHER_SEND_SMALL_SIZE);
>> + flags_next =
>> + MYRI10GE_MCP_ETHER_FLAGS_TSO_PLD |
>> + MYRI10GE_MCP_ETHER_FLAGS_FIRST |
>> + (small *
>> + MYRI10GE_MCP_ETHER_FLAGS_SMALL);
>> + }
>> + }
>>
>
> 100 characters per line are too much, as are six levels of intentation,
> or the number of lines in this function.
> You should try to split into into smaller ones.
>

We have tried :) But there is no nice way to split this code. So I guess
we will have to keep it like this.

Thanks,
Brice