diff options
Diffstat (limited to 'drivers/net/wimax/i2400m/tx.c')
| -rw-r--r-- | drivers/net/wimax/i2400m/tx.c | 75 |
1 files changed, 69 insertions, 6 deletions
diff --git a/drivers/net/wimax/i2400m/tx.c b/drivers/net/wimax/i2400m/tx.c index 613a88ffd65..fa16ccf8e26 100644 --- a/drivers/net/wimax/i2400m/tx.c +++ b/drivers/net/wimax/i2400m/tx.c @@ -278,6 +278,48 @@ enum { #define TAIL_FULL ((void *)~(unsigned long)NULL) /* + * Calculate how much tail room is available + * + * Note the trick here. This path is ONLY caleed for Case A (see + * i2400m_tx_fifo_push() below), where we have: + * + * Case A + * N ___________ + * | tail room | + * | | + * |<- IN ->| + * | | + * | data | + * | | + * |<- OUT ->| + * | | + * | head room | + * 0 ----------- + * + * When calculating the tail_room, tx_in might get to be zero if + * i2400m->tx_in is right at the end of the buffer (really full + * buffer) if there is no head room. In this case, tail_room would be + * I2400M_TX_BUF_SIZE, although it is actually zero. Hence the final + * mod (%) operation. However, when doing this kind of optimization, + * i2400m->tx_in being zero would fail, so we treat is an a special + * case. + */ +static inline +size_t __i2400m_tx_tail_room(struct i2400m *i2400m) +{ + size_t tail_room; + size_t tx_in; + + if (unlikely(i2400m->tx_in) == 0) + return I2400M_TX_BUF_SIZE; + tx_in = i2400m->tx_in % I2400M_TX_BUF_SIZE; + tail_room = I2400M_TX_BUF_SIZE - tx_in; + tail_room %= I2400M_TX_BUF_SIZE; + return tail_room; +} + + +/* * Allocate @size bytes in the TX fifo, return a pointer to it * * @i2400m: device descriptor @@ -338,7 +380,7 @@ void *i2400m_tx_fifo_push(struct i2400m *i2400m, size_t size, size_t padding) return NULL; } /* Is there space at the tail? */ - tail_room = I2400M_TX_BUF_SIZE - i2400m->tx_in % I2400M_TX_BUF_SIZE; + tail_room = __i2400m_tx_tail_room(i2400m); if (tail_room < needed_size) { if (i2400m->tx_out % I2400M_TX_BUF_SIZE < i2400m->tx_in % I2400M_TX_BUF_SIZE) { @@ -367,17 +409,29 @@ void *i2400m_tx_fifo_push(struct i2400m *i2400m, size_t size, size_t padding) * (I2400M_PL_PAD for the payloads, I2400M_TX_PLD_SIZE for the * header). * + * Tail room can get to be zero if a message was opened when there was + * space only for a header. _tx_close() will mark it as to-skip (as it + * will have no payloads) and there will be no more space to flush, so + * nothing has to be done here. This is probably cheaper than ensuring + * in _tx_new() that there is some space for payloads...as we could + * always possibly hit the same problem if the payload wouldn't fit. + * * Note: * * Assumes i2400m->tx_lock is taken, and we use that as a barrier + * + * This path is only taken for Case A FIFO situations [see + * i2400m_tx_fifo_push()] */ static void i2400m_tx_skip_tail(struct i2400m *i2400m) { struct device *dev = i2400m_dev(i2400m); size_t tx_in = i2400m->tx_in % I2400M_TX_BUF_SIZE; - size_t tail_room = I2400M_TX_BUF_SIZE - tx_in; + size_t tail_room = __i2400m_tx_tail_room(i2400m); struct i2400m_msg_hdr *msg = i2400m->tx_buf + tx_in; + if (unlikely(tail_room == 0)) + return; BUG_ON(tail_room < sizeof(*msg)); msg->size = tail_room | I2400M_TX_SKIP; d_printf(2, dev, "skip tail: skipping %zu bytes @%zu\n", @@ -474,10 +528,18 @@ void i2400m_tx_close(struct i2400m *i2400m) struct i2400m_msg_hdr *tx_msg_moved; size_t aligned_size, padding, hdr_size; void *pad_buf; + unsigned num_pls; if (tx_msg->size & I2400M_TX_SKIP) /* a skipper? nothing to do */ goto out; - + num_pls = le16_to_cpu(tx_msg->num_pls); + /* We can get this situation when a new message was started + * and there was no space to add payloads before hitting the + tail (and taking padding into consideration). */ + if (num_pls == 0) { + tx_msg->size |= I2400M_TX_SKIP; + goto out; + } /* Relocate the message header * * Find the current header size, align it to 16 and if we need @@ -491,7 +553,7 @@ void i2400m_tx_close(struct i2400m *i2400m) */ hdr_size = sizeof(*tx_msg) + le16_to_cpu(tx_msg->num_pls) * sizeof(tx_msg->pld[0]); - hdr_size = ALIGN(hdr_size, I2400M_PL_PAD); + hdr_size = ALIGN(hdr_size, I2400M_PL_ALIGN); tx_msg->offset = I2400M_TX_PLD_SIZE - hdr_size; tx_msg_moved = (void *) tx_msg + tx_msg->offset; memmove(tx_msg_moved, tx_msg, hdr_size); @@ -574,7 +636,7 @@ int i2400m_tx(struct i2400m *i2400m, const void *buf, size_t buf_len, d_fnstart(3, dev, "(i2400m %p skb %p [%zu bytes] pt %u)\n", i2400m, buf, buf_len, pl_type); - padded_len = ALIGN(buf_len, I2400M_PL_PAD); + padded_len = ALIGN(buf_len, I2400M_PL_ALIGN); d_printf(5, dev, "padded_len %zd buf_len %zd\n", padded_len, buf_len); /* If there is no current TX message, create one; if the * current one is out of payload slots or we have a singleton, @@ -591,6 +653,8 @@ try_new: i2400m_tx_close(i2400m); i2400m_tx_new(i2400m); } + if (i2400m->tx_msg == NULL) + goto error_tx_new; if (i2400m->tx_msg->size + padded_len > I2400M_TX_BUF_SIZE / 2) { d_printf(2, dev, "TX: message too big, going new\n"); i2400m_tx_close(i2400m); @@ -773,7 +837,6 @@ void i2400m_tx_msg_sent(struct i2400m *i2400m) n = i2400m->tx_out / I2400M_TX_BUF_SIZE; i2400m->tx_out %= I2400M_TX_BUF_SIZE; i2400m->tx_in -= n * I2400M_TX_BUF_SIZE; - netif_start_queue(i2400m->wimax_dev.net_dev); spin_unlock_irqrestore(&i2400m->tx_lock, flags); d_fnend(3, dev, "(i2400m %p) = void\n", i2400m); } |