Add a facility for devices, specifically network interfaces, that require

large to huge amounts of small or medium sized receive buffers. The problem
with these situations is that they eat up the available DMA address space
very quickly when using mbufs or even mbuf clusters. Additionally this
facility provides a direct mapping between 32-bit integers and these buffers.
This is needed for devices originally designed for 32-bit systems. Ususally
the virtual address of the buffer is used as a handle to find the buffer as
soon as it is returned by the card. This does not work for 64-bit machines
and hence this mapping is needed.

1 files changed, 399 insertions, 0 deletions

diff --git a/sys/kern/subr_mbpool.c b/sys/kern/subr_mbpool.c
new file mode 100644
index 0000000..02c25e8
--- /dev/null
+++ b/sys/kern/subr_mbpool.c
@@ -0,0 +1,399 @@
+/*
+ * Copyright (c) 2003
+ *	Fraunhofer Institute for Open Communication Systems (FhG Fokus).
+ * 	All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * Author: Hartmut Brandt <harti@freebsd.org>
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/kernel.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+
+#include <machine/bus.h>
+
+#include <sys/mbpool.h>
+
+MODULE_VERSION(libmbpool, 1);
+
+/*
+ * Memory is allocated as DMA-able pages. Each page is divided into a number
+ * of equal chunks where the last 4 bytes of each chunk are occupied by
+ * the page number and the chunk number. The caller must take these four
+ * bytes into account when specifying the chunk size. Each page is mapped by
+ * its own DMA map using the user specified DMA tag.
+ *
+ * Each chunk has a used and a card bit in the high bits of its page number.
+ *  0    0	chunk is free and may be allocated
+ *  1    1	chunk has been given to the interface
+ *  0    1	chunk is traveling through the system
+ *  1    0	illegal
+ */
+struct mbtrail {
+	uint16_t	chunk;
+	uint16_t	page;
+};
+#define	MBP_CARD	0x8000
+#define	MBP_USED	0x4000
+#define	MBP_PMSK	0x3fff		/* page number mask */
+#define	MBP_CMSK	0x01ff		/* chunk number mask */
+
+struct mbfree {
+	SLIST_ENTRY(mbfree) link;	/* link on free list */
+};
+
+struct mbpage {
+	bus_dmamap_t	map;		/* map for this page */
+	bus_addr_t	phy;		/* physical address */
+	void		*va;		/* the memory */
+};
+
+struct mbpool {
+	const char	*name;		/* a name for this pool */
+	bus_dma_tag_t	dmat;		/* tag for mapping */
+	u_int		max_pages;	/* maximum number of pages */
+	size_t		page_size;	/* size of each allocation */
+	size_t		chunk_size;	/* size of each external mbuf */
+
+	struct mtx	free_lock;	/* lock of free list */
+	SLIST_HEAD(, mbfree) free_list;	/* free list */
+	u_int		npages;		/* current number of pages */
+	u_int		nchunks;	/* chunks per page */
+	struct mbpage	pages[];	/* pages */
+};
+
+static MALLOC_DEFINE(M_MBPOOL, "mbpools", "mbuf pools");
+
+/*
+ * Make a trail pointer from a chunk pointer
+ */
+#define	C2T(P, C)	((struct mbtrail *)((char *)(C) + (P)->chunk_size - \
+			    sizeof(struct mbtrail)))
+
+/*
+ * Make a free chunk pointer from a chunk number
+ */
+#define	N2C(P, PG, C)	((struct mbfree *)((char *)(PG)->va + \
+			    (C) * (P)->chunk_size))
+
+/*
+ * Make/parse handles
+ */
+#define	HMAKE(P, C)	((((P) & MBP_PMSK) << 16) | ((C) << 7))
+#define	HPAGE(H)	(((H) >> 16) & MBP_PMSK)
+#define	HCHUNK(H)	(((H) >>  7) & MBP_CMSK)
+
+/*
+ * initialize a pool
+ */
+int
+mbp_create(struct mbpool **pp, const char *name, bus_dma_tag_t dmat,
+    u_int max_pages, size_t page_size, size_t chunk_size)
+{
+	u_int nchunks;
+
+	if (max_pages > MBPOOL_MAX_MAXPAGES || chunk_size == 0)
+		return (EINVAL);
+	nchunks = page_size / chunk_size;
+	if (nchunks == 0 || nchunks > MBPOOL_MAX_CHUNKS)
+		return (EINVAL);
+
+	(*pp) = malloc(sizeof(struct mbpool) +
+	    max_pages * sizeof(struct mbpage),
+	    M_MBPOOL, M_WAITOK | M_ZERO);
+
+	(*pp)->name = name;
+	(*pp)->dmat = dmat;
+	(*pp)->max_pages = max_pages;
+	(*pp)->page_size = page_size;
+	(*pp)->chunk_size = chunk_size;
+	(*pp)->nchunks = nchunks;
+
+	SLIST_INIT(&(*pp)->free_list);
+	mtx_init(&(*pp)->free_lock, name, NULL, 0);
+
+	return (0);
+}
+
+/*
+ * destroy a pool
+ */
+void
+mbp_destroy(struct mbpool *p)
+{
+	u_int i;
+	struct mbpage *pg;
+#ifdef DIAGNOSTIC
+	struct mbtrail *tr;
+	u_int b;
+#endif
+
+	for (i = 0; i < p->npages; i++) {
+		pg = &p->pages[i];
+#ifdef DIAGNOSTIC
+		for (b = 0; b < p->nchunks; b++) {
+			tr = C2T(p, N2C(p, pg, b));
+			if (tr->page & MBP_CARD)
+				printf("%s: (%s) buf still on card"
+				    " %u/%u\n", __func__, p->name, i, b);
+			if (tr->page & MBP_USED)
+				printf("%s: (%s) sbuf still in use"
+				    " %u/%u\n", __func__, p->name, i, b);
+		}
+#endif
+		bus_dmamap_unload(p->dmat, pg->map);
+		bus_dmamem_free(p->dmat, pg->va, pg->map);
+	}
+	mtx_destroy(&p->free_lock);
+
+	free(p, M_MBPOOL);
+}
+
+/*
+ * Helper function when loading a one segment DMA buffer.
+ */
+static void
+mbp_callback(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
+{
+	if (error == 0)
+		*(bus_addr_t *)arg = segs[0].ds_addr;
+}
+
+/*
+ * Allocate a new page
+ */
+static void
+mbp_alloc_page(struct mbpool *p)
+{
+	int error;
+	struct mbpage *pg;
+	u_int i;
+	struct mbfree *f;
+	struct mbtrail *t;
+
+	if (p->npages == p->max_pages) {
+#ifdef DIAGNOSTIC
+		printf("%s: (%s) page limit reached %u\n", __func__,
+		    p->name, p->max_pages);
+#endif
+		return;
+	}
+	pg = &p->pages[p->npages];
+
+	error = bus_dmamem_alloc(p->dmat, &pg->va, BUS_DMA_NOWAIT, &pg->map);
+	if (error != 0) {
+		free(pg, M_MBPOOL);
+		return;
+	}
+
+	error = bus_dmamap_load(p->dmat, pg->map, pg->va, p->page_size,
+	    mbp_callback, &pg->phy, 0);
+	if (error != 0) {
+		bus_dmamem_free(p->dmat, pg->va, pg->map);
+		free(pg, M_MBPOOL);
+		return;
+	}
+
+	for (i = 0; i < p->nchunks; i++) {
+		f = N2C(p, pg, i);
+		t = C2T(p, f);
+		t->page = p->npages;
+		t->chunk = i;
+		SLIST_INSERT_HEAD(&p->free_list, f, link);
+	}
+
+	p->npages++;
+}
+
+/*
+ * allocate a chunk
+ */
+void *
+mbp_alloc(struct mbpool *p, bus_addr_t *pap, uint32_t *hp)
+{
+	struct mbfree *cf;
+	struct mbtrail *t;
+
+	mtx_lock(&p->free_lock);
+	if ((cf = SLIST_FIRST(&p->free_list)) == NULL) {
+		mbp_alloc_page(p);
+		cf = SLIST_FIRST(&p->free_list);
+	}
+	if (cf == NULL) {
+		mtx_unlock(&p->free_lock);
+		return (NULL);
+	}
+	SLIST_REMOVE_HEAD(&p->free_list, link);
+	mtx_unlock(&p->free_lock);
+
+	t = C2T(p, cf);
+
+	*pap = p->pages[t->page].phy + t->chunk * p->chunk_size;
+	*hp = HMAKE(t->page, t->chunk);
+
+	t->page |= MBP_CARD | MBP_USED;
+
+	return (cf);
+}
+
+/*
+ * Free a chunk
+ */
+void
+mbp_free(struct mbpool *p, void *ptr)
+{
+	struct mbtrail *t;
+
+	mtx_lock(&p->free_lock);
+	t = C2T(p, ptr);
+	t->page &= ~(MBP_USED | MBP_CARD);
+	SLIST_INSERT_HEAD(&p->free_list, (struct mbfree *)ptr, link);
+	mtx_unlock(&p->free_lock);
+}
+
+/*
+ * Mbuf system external mbuf free routine
+ */
+void
+mbp_ext_free(void *buf, void *arg)
+{
+	mbp_free(arg, buf);
+}
+
+/*
+ * Free all buffers that are marked as beeing on the card
+ */
+void
+mbp_card_free(struct mbpool *p)
+{
+	u_int i, b;
+	struct mbpage *pg;
+	struct mbtrail *tr;
+	struct mbfree *cf;
+
+	mtx_lock(&p->free_lock);
+	for (i = 0; i < p->npages; i++) {
+		pg = &p->pages[i];
+		for (b = 0; b < p->nchunks; b++) {
+			cf = N2C(p, pg, b);
+			tr = C2T(p, cf);
+			if (tr->page & MBP_CARD) {
+				tr->page &= MBP_PMSK;
+				SLIST_INSERT_HEAD(&p->free_list, cf, link);
+			}
+		}
+	}
+	mtx_unlock(&p->free_lock);
+}
+
+/*
+ * Count buffers
+ */
+void
+mbp_count(struct mbpool *p, u_int *used, u_int *card, u_int *free)
+{
+	u_int i, b;
+	struct mbpage *pg;
+	struct mbtrail *tr;
+	struct mbfree *cf;
+
+	*used = *card = *free = 0;
+	for (i = 0; i < p->npages; i++) {
+		pg = &p->pages[i];
+		for (b = 0; b < p->nchunks; b++) {
+			tr = C2T(p, N2C(p, pg, b));
+			if (tr->page & MBP_CARD)
+				(*card)++;
+			if (tr->page & MBP_USED)
+				(*used)++;
+		}
+	}
+	mtx_lock(&p->free_lock);
+	SLIST_FOREACH(cf, &p->free_list, link)
+		*free++;
+	mtx_unlock(&p->free_lock);
+}
+
+/*
+ * Get the buffer from a handle and clear the card flag.
+ */
+void *
+mbp_get(struct mbpool *p, uint32_t h)
+{
+	struct mbfree *cf;
+	struct mbtrail *tr;
+
+	cf = N2C(p, &p->pages[HPAGE(h)], HCHUNK(h));
+	tr = C2T(p, cf);
+
+#ifdef DIAGNOSTIC
+	if (!(tr->page & MBP_CARD))
+		printf("%s: (%s) chunk %u page %u not on card\n", __func__,
+		    p->name, HCHUNK(h), HPAGE(h));
+#endif
+
+	tr->page &= ~MBP_CARD;
+	return (cf);
+}
+
+/*
+ * Get the buffer from a handle and keep the card flag.
+ */
+void *
+mbp_get_keep(struct mbpool *p, uint32_t h)
+{
+	struct mbfree *cf;
+	struct mbtrail *tr;
+
+	cf = N2C(p, &p->pages[HPAGE(h)], HCHUNK(h));
+	tr = C2T(p, cf);
+
+#ifdef DIAGNOSTIC
+	if (!(tr->page & MBP_CARD))
+		printf("%s: (%s) chunk %u page %u not on card\n", __func__,
+		    p->name, HCHUNK(h), HPAGE(h));
+#endif
+
+	return (cf);
+}
+
+/*
+ * sync the chunk
+ */
+void
+mbp_sync(struct mbpool *p, uint32_t h, bus_addr_t off, bus_size_t len, u_int op)
+{
+
+#if 0
+	bus_dmamap_sync_size(p->dmat, p->pages[HPAGE(h)].map,
+	    HCHUNK(h) * p->chunk_size + off, len, op);
+#endif
+}