diff options
Diffstat (limited to 'drivers/net/wimax/i2400m/tx.c')
| -rw-r--r-- | drivers/net/wimax/i2400m/tx.c | 153 |
1 files changed, 134 insertions, 19 deletions
diff --git a/drivers/net/wimax/i2400m/tx.c b/drivers/net/wimax/i2400m/tx.c index 6db909ecf1c..3f819efc06b 100644 --- a/drivers/net/wimax/i2400m/tx.c +++ b/drivers/net/wimax/i2400m/tx.c @@ -258,8 +258,10 @@ enum { * Doc says maximum transaction is 16KiB. If we had 16KiB en * route and 16KiB being queued, it boils down to needing * 32KiB. + * 32KiB is insufficient for 1400 MTU, hence increasing + * tx buffer size to 64KiB. */ - I2400M_TX_BUF_SIZE = 32768, + I2400M_TX_BUF_SIZE = 65536, /** * Message header and payload descriptors have to be 16 * aligned (16 + 4 * N = 16 * M). If we take that average sent @@ -270,10 +272,21 @@ enum { * at the end there are less, we pad up to the nearest * multiple of 16. */ - I2400M_TX_PLD_MAX = 12, + /* + * According to Intel Wimax i3200, i5x50 and i6x50 specification + * documents, the maximum number of payloads per message can be + * up to 60. Increasing the number of payloads to 60 per message + * helps to accommodate smaller payloads in a single transaction. + */ + I2400M_TX_PLD_MAX = 60, I2400M_TX_PLD_SIZE = sizeof(struct i2400m_msg_hdr) + I2400M_TX_PLD_MAX * sizeof(struct i2400m_pld), I2400M_TX_SKIP = 0x80000000, + /* + * According to Intel Wimax i3200, i5x50 and i6x50 specification + * documents, the maximum size of each message can be up to 16KiB. + */ + I2400M_TX_MSG_SIZE = 16384, }; #define TAIL_FULL ((void *)~(unsigned long)NULL) @@ -328,6 +341,14 @@ size_t __i2400m_tx_tail_room(struct i2400m *i2400m) * @padding: ensure that there is at least this many bytes of free * contiguous space in the fifo. This is needed because later on * we might need to add padding. + * @try_head: specify either to allocate head room or tail room space + * in the TX FIFO. This boolean is required to avoids a system hang + * due to an infinite loop caused by i2400m_tx_fifo_push(). + * The caller must always try to allocate tail room space first by + * calling this routine with try_head = 0. In case if there + * is not enough tail room space but there is enough head room space, + * (i2400m_tx_fifo_push() returns TAIL_FULL) try to allocate head + * room space, by calling this routine again with try_head = 1. * * Returns: * @@ -359,6 +380,48 @@ size_t __i2400m_tx_tail_room(struct i2400m *i2400m) * fail and return TAIL_FULL and let the caller figure out if we wants to * skip the tail room and try to allocate from the head. * + * There is a corner case, wherein i2400m_tx_new() can get into + * an infinite loop calling i2400m_tx_fifo_push(). + * In certain situations, tx_in would have reached on the top of TX FIFO + * and i2400m_tx_tail_room() returns 0, as described below: + * + * N ___________ tail room is zero + * |<- IN ->| + * | | + * | | + * | | + * | data | + * |<- OUT ->| + * | | + * | | + * | head room | + * 0 ----------- + * During such a time, where tail room is zero in the TX FIFO and if there + * is a request to add a payload to TX FIFO, which calls: + * i2400m_tx() + * ->calls i2400m_tx_close() + * ->calls i2400m_tx_skip_tail() + * goto try_new; + * ->calls i2400m_tx_new() + * |----> [try_head:] + * infinite loop | ->calls i2400m_tx_fifo_push() + * | if (tail_room < needed) + * | if (head_room => needed) + * | return TAIL_FULL; + * |<---- goto try_head; + * + * i2400m_tx() calls i2400m_tx_close() to close the message, since there + * is no tail room to accommodate the payload and calls + * i2400m_tx_skip_tail() to skip the tail space. Now i2400m_tx() calls + * i2400m_tx_new() to allocate space for new message header calling + * i2400m_tx_fifo_push() that returns TAIL_FULL, since there is no tail space + * to accommodate the message header, but there is enough head space. + * The i2400m_tx_new() keeps re-retrying by calling i2400m_tx_fifo_push() + * ending up in a loop causing system freeze. + * + * This corner case is avoided by using a try_head boolean, + * as an argument to i2400m_tx_fifo_push(). + * * Note: * * Assumes i2400m->tx_lock is taken, and we use that as a barrier @@ -367,7 +430,8 @@ size_t __i2400m_tx_tail_room(struct i2400m *i2400m) * pop data off the queue */ static -void *i2400m_tx_fifo_push(struct i2400m *i2400m, size_t size, size_t padding) +void *i2400m_tx_fifo_push(struct i2400m *i2400m, size_t size, + size_t padding, bool try_head) { struct device *dev = i2400m_dev(i2400m); size_t room, tail_room, needed_size; @@ -382,9 +446,21 @@ void *i2400m_tx_fifo_push(struct i2400m *i2400m, size_t size, size_t padding) } /* Is there space at the tail? */ 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) { + if (!try_head && tail_room < needed_size) { + /* + * If the tail room space is not enough to push the message + * in the TX FIFO, then there are two possibilities: + * 1. There is enough head room space to accommodate + * this message in the TX FIFO. + * 2. There is not enough space in the head room and + * in tail room of the TX FIFO to accommodate the message. + * In the case (1), return TAIL_FULL so that the caller + * can figure out, if the caller wants to push the message + * into the head room space. + * In the case (2), return NULL, indicating that the TX FIFO + * cannot accommodate the message. + */ + if (room - tail_room >= needed_size) { d_printf(2, dev, "fifo push %zu/%zu: tail full\n", size, padding); return TAIL_FULL; /* There might be head space */ @@ -485,14 +561,25 @@ void i2400m_tx_new(struct i2400m *i2400m) { struct device *dev = i2400m_dev(i2400m); struct i2400m_msg_hdr *tx_msg; + bool try_head = 0; BUG_ON(i2400m->tx_msg != NULL); + /* + * In certain situations, TX queue might have enough space to + * accommodate the new message header I2400M_TX_PLD_SIZE, but + * might not have enough space to accommodate the payloads. + * Adding bus_tx_room_min padding while allocating a new TX message + * increases the possibilities of including at least one payload of the + * size <= bus_tx_room_min. + */ try_head: - tx_msg = i2400m_tx_fifo_push(i2400m, I2400M_TX_PLD_SIZE, 0); + tx_msg = i2400m_tx_fifo_push(i2400m, I2400M_TX_PLD_SIZE, + i2400m->bus_tx_room_min, try_head); if (tx_msg == NULL) goto out; else if (tx_msg == TAIL_FULL) { i2400m_tx_skip_tail(i2400m); d_printf(2, dev, "new TX message: tail full, trying head\n"); + try_head = 1; goto try_head; } memset(tx_msg, 0, I2400M_TX_PLD_SIZE); @@ -566,7 +653,7 @@ void i2400m_tx_close(struct i2400m *i2400m) aligned_size = ALIGN(tx_msg_moved->size, i2400m->bus_tx_block_size); padding = aligned_size - tx_msg_moved->size; if (padding > 0) { - pad_buf = i2400m_tx_fifo_push(i2400m, padding, 0); + pad_buf = i2400m_tx_fifo_push(i2400m, padding, 0, 0); if (unlikely(WARN_ON(pad_buf == NULL || pad_buf == TAIL_FULL))) { /* This should not happen -- append should verify @@ -632,6 +719,7 @@ int i2400m_tx(struct i2400m *i2400m, const void *buf, size_t buf_len, unsigned long flags; size_t padded_len; void *ptr; + bool try_head = 0; unsigned is_singleton = pl_type == I2400M_PT_RESET_WARM || pl_type == I2400M_PT_RESET_COLD; @@ -643,9 +731,11 @@ int i2400m_tx(struct i2400m *i2400m, const void *buf, size_t buf_len, * current one is out of payload slots or we have a singleton, * close it and start a new one */ spin_lock_irqsave(&i2400m->tx_lock, flags); - result = -ESHUTDOWN; - if (i2400m->tx_buf == NULL) + /* If tx_buf is NULL, device is shutdown */ + if (i2400m->tx_buf == NULL) { + result = -ESHUTDOWN; goto error_tx_new; + } try_new: if (unlikely(i2400m->tx_msg == NULL)) i2400m_tx_new(i2400m); @@ -659,7 +749,13 @@ try_new: } if (i2400m->tx_msg == NULL) goto error_tx_new; - if (i2400m->tx_msg->size + padded_len > I2400M_TX_BUF_SIZE / 2) { + /* + * Check if this skb will fit in the TX queue's current active + * TX message. The total message size must not exceed the maximum + * size of each message I2400M_TX_MSG_SIZE. If it exceeds, + * close the current message and push this skb into the new message. + */ + if (i2400m->tx_msg->size + padded_len > I2400M_TX_MSG_SIZE) { d_printf(2, dev, "TX: message too big, going new\n"); i2400m_tx_close(i2400m); i2400m_tx_new(i2400m); @@ -669,11 +765,12 @@ try_new: /* So we have a current message header; now append space for * the message -- if there is not enough, try the head */ ptr = i2400m_tx_fifo_push(i2400m, padded_len, - i2400m->bus_tx_block_size); + i2400m->bus_tx_block_size, try_head); if (ptr == TAIL_FULL) { /* Tail is full, try head */ d_printf(2, dev, "pl append: tail full\n"); i2400m_tx_close(i2400m); i2400m_tx_skip_tail(i2400m); + try_head = 1; goto try_new; } else if (ptr == NULL) { /* All full */ result = -ENOSPC; @@ -860,25 +957,43 @@ EXPORT_SYMBOL_GPL(i2400m_tx_msg_sent); * i2400m_tx_setup - Initialize the TX queue and infrastructure * * Make sure we reset the TX sequence to zero, as when this function - * is called, the firmware has been just restarted. + * is called, the firmware has been just restarted. Same rational + * for tx_in, tx_out, tx_msg_size and tx_msg. We reset them since + * the memory for TX queue is reallocated. */ int i2400m_tx_setup(struct i2400m *i2400m) { - int result; + int result = 0; + void *tx_buf; + unsigned long flags; /* Do this here only once -- can't do on * i2400m_hard_start_xmit() as we'll cause race conditions if * the WS was scheduled on another CPU */ INIT_WORK(&i2400m->wake_tx_ws, i2400m_wake_tx_work); - i2400m->tx_sequence = 0; - i2400m->tx_buf = kmalloc(I2400M_TX_BUF_SIZE, GFP_KERNEL); - if (i2400m->tx_buf == NULL) + tx_buf = kmalloc(I2400M_TX_BUF_SIZE, GFP_ATOMIC); + if (tx_buf == NULL) { result = -ENOMEM; - else - result = 0; + goto error_kmalloc; + } + + /* + * Fail the build if we can't fit at least two maximum size messages + * on the TX FIFO [one being delivered while one is constructed]. + */ + BUILD_BUG_ON(2 * I2400M_TX_MSG_SIZE > I2400M_TX_BUF_SIZE); + spin_lock_irqsave(&i2400m->tx_lock, flags); + i2400m->tx_sequence = 0; + i2400m->tx_in = 0; + i2400m->tx_out = 0; + i2400m->tx_msg_size = 0; + i2400m->tx_msg = NULL; + i2400m->tx_buf = tx_buf; + spin_unlock_irqrestore(&i2400m->tx_lock, flags); /* Huh? the bus layer has to define this... */ BUG_ON(i2400m->bus_tx_block_size == 0); +error_kmalloc: return result; } |