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path: root/drivers/net/wimax/i2400m/tx.c
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Diffstat (limited to 'drivers/net/wimax/i2400m/tx.c')
-rw-r--r--drivers/net/wimax/i2400m/tx.c155
1 files changed, 135 insertions, 20 deletions
diff --git a/drivers/net/wimax/i2400m/tx.c b/drivers/net/wimax/i2400m/tx.c
index b0cb90624cf..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;
@@ -689,7 +786,7 @@ try_new:
pl_type, buf_len);
tx_msg->num_pls = le16_to_cpu(num_pls+1);
tx_msg->size += padded_len;
- d_printf(2, dev, "TX: appended %zu b (up to %u b) pl #%u \n",
+ d_printf(2, dev, "TX: appended %zu b (up to %u b) pl #%u\n",
padded_len, tx_msg->size, num_pls+1);
d_printf(2, dev,
"TX: appended hdr @%zu %zu b pl #%u @%zu %zu/%zu b\n",
@@ -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;
}