diff options
Diffstat (limited to 'drivers/net/wimax/i2400m/tx.c')
| -rw-r--r-- | drivers/net/wimax/i2400m/tx.c | 250 |
1 files changed, 223 insertions, 27 deletions
diff --git a/drivers/net/wimax/i2400m/tx.c b/drivers/net/wimax/i2400m/tx.c index 613a88ffd65..f20886ade1c 100644 --- a/drivers/net/wimax/i2400m/tx.c +++ b/drivers/net/wimax/i2400m/tx.c @@ -149,7 +149,7 @@ * (with a moved message header to make sure it is size-aligned to * 16), TAIL room that was unusable (and thus is marked with a message * header that says 'skip this') and at the head of the buffer, an - * imcomplete message with a couple of payloads. + * incomplete message with a couple of payloads. * * N ___________________________________________________ * | | @@ -244,6 +244,8 @@ * (FIFO empty). */ #include <linux/netdevice.h> +#include <linux/slab.h> +#include <linux/export.h> #include "i2400m.h" @@ -257,8 +259,10 @@ 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 @@ -269,15 +273,68 @@ 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) /* + * 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 @@ -285,6 +342,14 @@ enum { * @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: * @@ -316,6 +381,48 @@ enum { * 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 @@ -324,7 +431,8 @@ enum { * 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; @@ -338,10 +446,22 @@ 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; - if (tail_room < needed_size) { - if (i2400m->tx_out % I2400M_TX_BUF_SIZE - < i2400m->tx_in % I2400M_TX_BUF_SIZE) { + tail_room = __i2400m_tx_tail_room(i2400m); + 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 */ @@ -367,17 +487,29 @@ 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", @@ -430,14 +562,25 @@ void i2400m_tx_new(struct i2400m *i2400m) { struct device *dev = i2400m_dev(i2400m); struct i2400m_msg_hdr *tx_msg; + bool try_head = false; 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 = true; goto try_head; } memset(tx_msg, 0, I2400M_TX_PLD_SIZE); @@ -474,10 +617,18 @@ 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 +642,7 @@ 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); @@ -503,7 +654,7 @@ 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 @@ -569,17 +720,23 @@ 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 = false; unsigned is_singleton = pl_type == I2400M_PT_RESET_WARM || pl_type == I2400M_PT_RESET_COLD; 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, * close it and start a new one */ spin_lock_irqsave(&i2400m->tx_lock, flags); + /* 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); @@ -591,7 +748,15 @@ try_new: i2400m_tx_close(i2400m); i2400m_tx_new(i2400m); } - if (i2400m->tx_msg->size + padded_len > I2400M_TX_BUF_SIZE / 2) { + if (i2400m->tx_msg == NULL) + goto error_tx_new; + /* + * 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); @@ -601,11 +766,12 @@ 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 = true; goto try_new; } else if (ptr == NULL) { /* All full */ result = -ENOSPC; @@ -621,7 +787,7 @@ 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", @@ -633,7 +799,10 @@ try_new: } error_tx_new: spin_unlock_irqrestore(&i2400m->tx_lock, flags); - i2400m->bus_tx_kick(i2400m); /* always kick, might free up space */ + /* kick in most cases, except when the TX subsys is down, as + * it might free space */ + if (likely(result != -ESHUTDOWN)) + i2400m->bus_tx_kick(i2400m); d_fnend(3, dev, "(i2400m %p skb %p [%zu bytes] pt %u) = %d\n", i2400m, buf, buf_len, pl_type, result); return result; @@ -651,7 +820,7 @@ EXPORT_SYMBOL_GPL(i2400m_tx); * the FIF that is ready for transmission. * * It sets the state in @i2400m to indicate the bus-specific driver is - * transfering that message (i2400m->tx_msg_size). + * transferring that message (i2400m->tx_msg_size). * * Once the transfer is completed, call i2400m_tx_msg_sent(). * @@ -676,6 +845,9 @@ struct i2400m_msg_hdr *i2400m_tx_msg_get(struct i2400m *i2400m, d_fnstart(3, dev, "(i2400m %p bus_size %p)\n", i2400m, bus_size); spin_lock_irqsave(&i2400m->tx_lock, flags); + tx_msg_moved = NULL; + if (i2400m->tx_buf == NULL) + goto out_unlock; skip: tx_msg_moved = NULL; if (i2400m->tx_in == i2400m->tx_out) { /* Empty FIFO? */ @@ -765,6 +937,8 @@ void i2400m_tx_msg_sent(struct i2400m *i2400m) d_fnstart(3, dev, "(i2400m %p)\n", i2400m); spin_lock_irqsave(&i2400m->tx_lock, flags); + if (i2400m->tx_buf == NULL) + goto out_unlock; i2400m->tx_out += i2400m->tx_msg_size; d_printf(2, dev, "TX: sent %zu b\n", (size_t) i2400m->tx_msg_size); i2400m->tx_msg_size = 0; @@ -773,7 +947,7 @@ 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); +out_unlock: spin_unlock_irqrestore(&i2400m->tx_lock, flags); d_fnend(3, dev, "(i2400m %p) = void\n", i2400m); } @@ -784,25 +958,43 @@ 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; } @@ -813,5 +1005,9 @@ int i2400m_tx_setup(struct i2400m *i2400m) */ void i2400m_tx_release(struct i2400m *i2400m) { + unsigned long flags; + spin_lock_irqsave(&i2400m->tx_lock, flags); kfree(i2400m->tx_buf); + i2400m->tx_buf = NULL; + spin_unlock_irqrestore(&i2400m->tx_lock, flags); } |