|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [UNIKRAFT PATCH 2/4] lib/uknetdev: netbuf: Metadata at the end of an allocation
Place the netbuf metadata (`struct netbuf`) at the end of an allocation.
This enables forwarding possible alignments of an underlying allocation
to the buffer area of a netbuf. The metadata will no longer cause an offset
of the buffer start address (`m->buf`).
Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
lib/uknetdev/include/uk/netbuf.h | 29 +++++-----
lib/uknetdev/netbuf.c | 97 ++++++++++++--------------------
2 files changed, 50 insertions(+), 76 deletions(-)
diff --git a/lib/uknetdev/include/uk/netbuf.h b/lib/uknetdev/include/uk/netbuf.h
index f21d082b..ea803ae8 100644
--- a/lib/uknetdev/include/uk/netbuf.h
+++ b/lib/uknetdev/include/uk/netbuf.h
@@ -57,18 +57,6 @@ typedef void (*uk_netbuf_dtor_t)(struct uk_netbuf *);
* The structure can be chained to describe a packet with multiple scattered
* buffers.
*
- * NETBUF
- * +----------------------+
- * | struct uk_netbuf |
- * | |
- * +----------------------+
- *
- * PRIVATE META DATA
- * *priv -> +----------------------+
- * | private meta |
- * | data area |
- * +----------------------+
- *
* PACKET BUFFER
* *buf -> +----------------------+ \
* | HEAD ROOM | |
@@ -82,6 +70,17 @@ typedef void (*uk_netbuf_dtor_t)(struct uk_netbuf *);
* | TAIL ROOM | |
* *buf + buflen -> +----------------------+ /
*
+ * NETBUF
+ * +----------------------+
+ * | struct uk_netbuf |
+ * | |
+ * +----------------------+
+ *
+ * PRIVATE META DATA
+ * *priv -> +----------------------+
+ * | private meta |
+ * | data area |
+ * +----------------------+
*
* The private data area is intended for glue code that wants to embed stack-
* specific data to the netbuf (e.g., `struct pbuf` for lwIP). This avoids
@@ -237,7 +236,8 @@ struct uk_netbuf *uk_netbuf_alloc_indir(struct uk_alloc *a,
/**
* Allocate and initialize netbuf with data buffer area.
- * m->len is initialized with 0.
+ * m->len is initialized with 0. Metadata (struct uknetbuf, priv)
+ * is placed at the end of the according allocation.
* @param a
* Allocator to be used for allocating `struct uk_netbuf` and the
* corresponding buffer area (single allocation).
@@ -268,7 +268,8 @@ struct uk_netbuf *uk_netbuf_alloc_buf(struct uk_alloc *a,
size_t buflen,
/**
* Initialize netbuf with data buffer on a user given allocated memory area
- * m->len is initialized with 0.
+ * m->len is initialized with 0. Metadata (struct uknetbuf, priv)
+ * is placed at the end of the given allocation.
* @param mem
* Reference to user provided memory region
* @param buflen
diff --git a/lib/uknetdev/netbuf.c b/lib/uknetdev/netbuf.c
index 5156e808..c5cf662e 100644
--- a/lib/uknetdev/netbuf.c
+++ b/lib/uknetdev/netbuf.c
@@ -37,7 +37,10 @@
/* Used to align netbuf's priv and data areas to `long long` data type */
#define NETBUF_ADDR_ALIGNMENT (sizeof(long long))
-#define NETBUF_ADDR_ALIGN_UP(x) ALIGN_UP((x), NETBUF_ADDR_ALIGNMENT)
+#define NETBUF_ADDR_ALIGN_UP(x) ALIGN_UP((__uptr) (x), \
+ NETBUF_ADDR_ALIGNMENT)
+#define NETBUF_ADDR_ALIGN_DOWN(x) ALIGN_DOWN((__uptr) (x), \
+ NETBUF_ADDR_ALIGNMENT)
void uk_netbuf_init_indir(struct uk_netbuf *m,
void *buf, size_t buflen, uint16_t headroom,
@@ -99,52 +102,34 @@ struct uk_netbuf *uk_netbuf_alloc_buf(struct uk_alloc *a,
size_t buflen,
uint16_t headroom,
size_t privlen, uk_netbuf_dtor_t dtor)
{
+ void *mem;
+ size_t alloc_len;
struct uk_netbuf *m;
- size_t buf_offset = 0;
- size_t priv_offset = 0;
- size_t headroom_extra = 0;
UK_ASSERT(buflen > 0);
UK_ASSERT(headroom <= buflen);
- m = uk_malloc(a, NETBUF_ADDR_ALIGN_UP(sizeof(*m))
- + NETBUF_ADDR_ALIGN_UP(privlen)
- + buflen);
- if (!m)
+ alloc_len = NETBUF_ADDR_ALIGN_UP(buflen)
+ + NETBUF_ADDR_ALIGN_UP(sizeof(*m) + privlen);
+ mem = uk_malloc(a, alloc_len);
+ if (!mem)
return NULL;
- /* Place buf right behind `m` or `m->priv` region if privlen > 0.
- * In order to keep `m->data - headroom` aligned the padding bytes
- * are added to the headroom.
- * We can only do this if the given headroom stays within
- * uint16_t bounds after the operation.
- */
- if (likely((size_t)(UINT16_MAX - headroom) > NETBUF_ADDR_ALIGNMENT)) {
- if (privlen == 0) {
- priv_offset = 0;
- buf_offset = sizeof(*m);
- headroom_extra = NETBUF_ADDR_ALIGN_UP(sizeof(*m))
- - sizeof(*m);
- } else {
- priv_offset = NETBUF_ADDR_ALIGN_UP(sizeof(*m));
- buf_offset = priv_offset + privlen;
- headroom_extra = NETBUF_ADDR_ALIGN_UP(privlen)
- - privlen;
- }
+ m = uk_netbuf_prepare_buf(mem,
+ alloc_len,
+ headroom,
+ privlen,
+ dtor);
+ if (!m) {
+ uk_free(a, mem);
+ return NULL;
}
- uk_netbuf_init_indir(m,
- (void *) m + buf_offset,
- buflen + headroom_extra,
- headroom + headroom_extra,
- privlen > 0 ? ((void *) m + priv_offset) : NULL,
- dtor);
-
/* Save reference to allocator and allocation
* that is used for free'ing this uk_netbuf.
*/
m->_a = a;
- m->_b = m;
+ m->_b = mem;
return m;
}
@@ -154,41 +139,29 @@ struct uk_netbuf *uk_netbuf_prepare_buf(void *mem, size_t
size,
size_t privlen, uk_netbuf_dtor_t dtor)
{
struct uk_netbuf *m;
- size_t buf_offset = 0;
- size_t priv_offset = 0;
+ size_t meta_len = 0;
UK_ASSERT(mem);
- if ((NETBUF_ADDR_ALIGN_UP(sizeof(*m))
- + NETBUF_ADDR_ALIGN_UP(privlen)
- + headroom) > size)
- return NULL;
- /* Place buf right behind `m` or `m->priv` region if privlen > 0.
- * In order to keep `m->data - headroom` aligned the padding bytes
- * are added to the headroom.
- * We can only do this if the given headroom stays within
- * uint16_t bounds after the operation.
+ /* Place headroom and buf at the beginning of the allocation,
+ * This is done in order to forward potential alignments of the
+ * underlying allocation directly to the netbuf data area.
+ * `m` (followed by `m->priv` if privlen > 0) will be placed at
+ * the end of the given memory.
*/
- if (likely((size_t)(UINT16_MAX - headroom) > NETBUF_ADDR_ALIGNMENT)) {
- if (privlen == 0) {
- priv_offset = 0;
- buf_offset = sizeof(*m);
- headroom += NETBUF_ADDR_ALIGN_UP(sizeof(*m))
- - sizeof(*m);
- } else {
- priv_offset = NETBUF_ADDR_ALIGN_UP(sizeof(*m));
- buf_offset = priv_offset + privlen;
- headroom += NETBUF_ADDR_ALIGN_UP(privlen)
- - privlen;
- }
- }
+ meta_len = NETBUF_ADDR_ALIGN_UP(sizeof(*m) + privlen);
+ if (meta_len > NETBUF_ADDR_ALIGN_DOWN((__uptr) mem + size))
+ return NULL;
+
+ m = (struct uk_netbuf *) (NETBUF_ADDR_ALIGN_DOWN((__uptr) mem + size)
+ - meta_len);
- m = (struct uk_netbuf *) mem;
uk_netbuf_init_indir(m,
- mem + buf_offset,
- size - buf_offset,
+ mem,
+ (size_t) ((__uptr) m - (__uptr) mem),
headroom,
- privlen > 0 ? (mem + priv_offset) : NULL,
+ privlen > 0 ? (void *) ((__uptr) m+ sizeof(*m))
+ : NULL,
dtor);
return m;
}
--
2.20.1
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |