[SCSI] libfcoe: Move common code from fcoe to libfcoe module

To facilitate LLDDs to reuse the code, skb queue related functions are moved to
libfcoe, so that both fcoe and bnx2fc drivers can use them. The common structures
fcoe_port, fcoe_percpu_s are moved to libfcoe. fcoe_port will now have an
opaque pointer that points to corresponding driver's interface structure.
Also, fcoe_start_io and fcoe_fc_crc are moved to libfcoe.

As part of this change, fixed fcoe_start_io to return ENOMEM if
skb_clone fails.

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 200 insertions, 0 deletions

diff --git a/drivers/scsi/fcoe/fcoe_transport.c b/drivers/scsi/fcoe/fcoe_transport.c
index e5aef563912..745eb9a22d6 100644
--- a/drivers/scsi/fcoe/fcoe_transport.c
+++ b/drivers/scsi/fcoe/fcoe_transport.c
@@ -23,6 +23,7 @@
 #include <linux/list.h>
 #include <linux/netdevice.h>
 #include <linux/errno.h>
+#include <linux/crc32.h>
 #include <scsi/libfcoe.h>
 
 #include "libfcoe.h"
@@ -75,6 +76,205 @@ __MODULE_PARM_TYPE(disable, "string");
 MODULE_PARM_DESC(disable, " Disables fcoe on a ethernet interface.");
 
 /**
+ * fcoe_fc_crc() - Calculates the CRC for a given frame
+ * @fp: The frame to be checksumed
+ *
+ * This uses crc32() routine to calculate the CRC for a frame
+ *
+ * Return: The 32 bit CRC value
+ */
+u32 fcoe_fc_crc(struct fc_frame *fp)
+{
+	struct sk_buff *skb = fp_skb(fp);
+	struct skb_frag_struct *frag;
+	unsigned char *data;
+	unsigned long off, len, clen;
+	u32 crc;
+	unsigned i;
+
+	crc = crc32(~0, skb->data, skb_headlen(skb));
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		frag = &skb_shinfo(skb)->frags[i];
+		off = frag->page_offset;
+		len = frag->size;
+		while (len > 0) {
+			clen = min(len, PAGE_SIZE - (off & ~PAGE_MASK));
+			data = kmap_atomic(frag->page + (off >> PAGE_SHIFT),
+					   KM_SKB_DATA_SOFTIRQ);
+			crc = crc32(crc, data + (off & ~PAGE_MASK), clen);
+			kunmap_atomic(data, KM_SKB_DATA_SOFTIRQ);
+			off += clen;
+			len -= clen;
+		}
+	}
+	return crc;
+}
+EXPORT_SYMBOL_GPL(fcoe_fc_crc);
+
+/**
+ * fcoe_start_io() - Start FCoE I/O
+ * @skb: The packet to be transmitted
+ *
+ * This routine is called from the net device to start transmitting
+ * FCoE packets.
+ *
+ * Returns: 0 for success
+ */
+int fcoe_start_io(struct sk_buff *skb)
+{
+	struct sk_buff *nskb;
+	int rc;
+
+	nskb = skb_clone(skb, GFP_ATOMIC);
+	if (!nskb)
+		return -ENOMEM;
+	rc = dev_queue_xmit(nskb);
+	if (rc != 0)
+		return rc;
+	kfree_skb(skb);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fcoe_start_io);
+
+
+/**
+ * fcoe_clean_pending_queue() - Dequeue a skb and free it
+ * @lport: The local port to dequeue a skb on
+ */
+void fcoe_clean_pending_queue(struct fc_lport *lport)
+{
+	struct fcoe_port  *port = lport_priv(lport);
+	struct sk_buff *skb;
+
+	spin_lock_bh(&port->fcoe_pending_queue.lock);
+	while ((skb = __skb_dequeue(&port->fcoe_pending_queue)) != NULL) {
+		spin_unlock_bh(&port->fcoe_pending_queue.lock);
+		kfree_skb(skb);
+		spin_lock_bh(&port->fcoe_pending_queue.lock);
+	}
+	spin_unlock_bh(&port->fcoe_pending_queue.lock);
+}
+EXPORT_SYMBOL_GPL(fcoe_clean_pending_queue);
+
+/**
+ * fcoe_check_wait_queue() - Attempt to clear the transmit backlog
+ * @lport: The local port whose backlog is to be cleared
+ *
+ * This empties the wait_queue, dequeues the head of the wait_queue queue
+ * and calls fcoe_start_io() for each packet. If all skb have been
+ * transmitted it returns the qlen. If an error occurs it restores
+ * wait_queue (to try again later) and returns -1.
+ *
+ * The wait_queue is used when the skb transmit fails. The failed skb
+ * will go in the wait_queue which will be emptied by the timer function or
+ * by the next skb transmit.
+ */
+void fcoe_check_wait_queue(struct fc_lport *lport, struct sk_buff *skb)
+{
+	struct fcoe_port *port = lport_priv(lport);
+	int rc;
+
+	spin_lock_bh(&port->fcoe_pending_queue.lock);
+
+	if (skb)
+		__skb_queue_tail(&port->fcoe_pending_queue, skb);
+
+	if (port->fcoe_pending_queue_active)
+		goto out;
+	port->fcoe_pending_queue_active = 1;
+
+	while (port->fcoe_pending_queue.qlen) {
+		/* keep qlen > 0 until fcoe_start_io succeeds */
+		port->fcoe_pending_queue.qlen++;
+		skb = __skb_dequeue(&port->fcoe_pending_queue);
+
+		spin_unlock_bh(&port->fcoe_pending_queue.lock);
+		rc = fcoe_start_io(skb);
+		spin_lock_bh(&port->fcoe_pending_queue.lock);
+
+		if (rc) {
+			__skb_queue_head(&port->fcoe_pending_queue, skb);
+			/* undo temporary increment above */
+			port->fcoe_pending_queue.qlen--;
+			break;
+		}
+		/* undo temporary increment above */
+		port->fcoe_pending_queue.qlen--;
+	}
+
+	if (port->fcoe_pending_queue.qlen < port->min_queue_depth)
+		lport->qfull = 0;
+	if (port->fcoe_pending_queue.qlen && !timer_pending(&port->timer))
+		mod_timer(&port->timer, jiffies + 2);
+	port->fcoe_pending_queue_active = 0;
+out:
+	if (port->fcoe_pending_queue.qlen > port->max_queue_depth)
+		lport->qfull = 1;
+	spin_unlock_bh(&port->fcoe_pending_queue.lock);
+}
+EXPORT_SYMBOL_GPL(fcoe_check_wait_queue);
+
+/**
+ * fcoe_queue_timer() - The fcoe queue timer
+ * @lport: The local port
+ *
+ * Calls fcoe_check_wait_queue on timeout
+ */
+void fcoe_queue_timer(ulong lport)
+{
+	fcoe_check_wait_queue((struct fc_lport *)lport, NULL);
+}
+EXPORT_SYMBOL_GPL(fcoe_queue_timer);
+
+/**
+ * fcoe_get_paged_crc_eof() - Allocate a page to be used for the trailer CRC
+ * @skb:  The packet to be transmitted
+ * @tlen: The total length of the trailer
+ * @fps:  The fcoe context
+ *
+ * This routine allocates a page for frame trailers. The page is re-used if
+ * there is enough room left on it for the current trailer. If there isn't
+ * enough buffer left a new page is allocated for the trailer. Reference to
+ * the page from this function as well as the skbs using the page fragments
+ * ensure that the page is freed at the appropriate time.
+ *
+ * Returns: 0 for success
+ */
+int fcoe_get_paged_crc_eof(struct sk_buff *skb, int tlen,
+			   struct fcoe_percpu_s *fps)
+{
+	struct page *page;
+
+	page = fps->crc_eof_page;
+	if (!page) {
+		page = alloc_page(GFP_ATOMIC);
+		if (!page)
+			return -ENOMEM;
+
+		fps->crc_eof_page = page;
+		fps->crc_eof_offset = 0;
+	}
+
+	get_page(page);
+	skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags, page,
+			   fps->crc_eof_offset, tlen);
+	skb->len += tlen;
+	skb->data_len += tlen;
+	skb->truesize += tlen;
+	fps->crc_eof_offset += sizeof(struct fcoe_crc_eof);
+
+	if (fps->crc_eof_offset >= PAGE_SIZE) {
+		fps->crc_eof_page = NULL;
+		fps->crc_eof_offset = 0;
+		put_page(page);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fcoe_get_paged_crc_eof);
+
+/**
  * fcoe_transport_lookup - find an fcoe transport that matches a netdev
  * @netdev: The netdev to look for from all attached transports
  *