Commit 6a632625c7da7594d059b88dae0e9c591af147ba
Committed by
David S. Miller
David S. Miller
1 parent
4f64bcb2fc
Exists in
master
and in
7 other branches
ethoc: remove division from loops
Calculating the BD entry using a modulus operation isn't optimal, especially
inside the loop. This patch removes the modulus operations in favour of:
i) simply checking for wrapping in the case of cur_rx
ii) forcing num_tx to be a power of two and using it to mask out the
entry from cur_tx
The also prevents possible issues related overflow of the cur_rx and cur_tx
counters.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Showing 1 changed file with 13 additions and 4 deletions Side-by-side Diff
drivers/net/ethoc.c
| ... | ... | @@ -412,7 +412,7 @@ |
| 412 | 412 | unsigned int entry; |
| 413 | 413 | struct ethoc_bd bd; |
| 414 | 414 | |
| 415 | - entry = priv->num_tx + (priv->cur_rx % priv->num_rx); | |
| 415 | + entry = priv->num_tx + priv->cur_rx; | |
| 416 | 416 | ethoc_read_bd(priv, entry, &bd); |
| 417 | 417 | if (bd.stat & RX_BD_EMPTY) { |
| 418 | 418 | ethoc_ack_irq(priv, INT_MASK_RX); |
| ... | ... | @@ -456,7 +456,8 @@ |
| 456 | 456 | bd.stat &= ~RX_BD_STATS; |
| 457 | 457 | bd.stat |= RX_BD_EMPTY; |
| 458 | 458 | ethoc_write_bd(priv, entry, &bd); |
| 459 | - priv->cur_rx++; | |
| 459 | + if (++priv->cur_rx == priv->num_rx) | |
| 460 | + priv->cur_rx = 0; | |
| 460 | 461 | } |
| 461 | 462 | |
| 462 | 463 | return count; |
| ... | ... | @@ -503,7 +504,7 @@ |
| 503 | 504 | for (count = 0; count < limit; ++count) { |
| 504 | 505 | unsigned int entry; |
| 505 | 506 | |
| 506 | - entry = priv->dty_tx % priv->num_tx; | |
| 507 | + entry = priv->dty_tx & (priv->num_tx-1); | |
| 507 | 508 | |
| 508 | 509 | ethoc_read_bd(priv, entry, &bd); |
| 509 | 510 | |
| 510 | 511 | |
| ... | ... | @@ -1000,8 +1001,16 @@ |
| 1000 | 1001 | /* calculate the number of TX/RX buffers, maximum 128 supported */ |
| 1001 | 1002 | num_bd = min_t(unsigned int, |
| 1002 | 1003 | 128, (netdev->mem_end - netdev->mem_start + 1) / ETHOC_BUFSIZ); |
| 1003 | - priv->num_tx = max(2, num_bd / 4); | |
| 1004 | + if (num_bd < 4) { | |
| 1005 | + ret = -ENODEV; | |
| 1006 | + goto error; | |
| 1007 | + } | |
| 1008 | + /* num_tx must be a power of two */ | |
| 1009 | + priv->num_tx = rounddown_pow_of_two(num_bd >> 1); | |
| 1004 | 1010 | priv->num_rx = num_bd - priv->num_tx; |
| 1011 | + | |
| 1012 | + dev_dbg(&pdev->dev, "ethoc: num_tx: %d num_rx: %d\n", | |
| 1013 | + priv->num_tx, priv->num_rx); | |
| 1005 | 1014 | |
| 1006 | 1015 | priv->vma = devm_kzalloc(&pdev->dev, num_bd*sizeof(void*), GFP_KERNEL); |
| 1007 | 1016 | if (!priv->vma) { |