Introduce 2 new helpers rte_pktmbuf_seg_is_shared() and
rte_pktmbuf_data_is_shared() to check if the packet data inside
a mbuf is shared (and shall not be modified).
To avoid a "discards const qualifier" error, add a const to the argument
of rte_mbuf_from_indirect().
Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
---
app/test/test_mbuf.c | 34 +++++++++++++++++++---
lib/librte_mbuf/rte_mbuf.h | 71 +++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 100 insertions(+), 5 deletions(-)
diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
index c0823ea..7656a4d 100644
--- a/app/test/test_mbuf.c
+++ b/app/test/test_mbuf.c
@@ -333,6 +333,7 @@ testclone_testupdate_testdetach(void)
struct rte_mbuf *m = NULL;
struct rte_mbuf *clone = NULL;
struct rte_mbuf *clone2 = NULL;
+ struct rte_mbuf *m2 = NULL;
unaligned_uint32_t *data;
/* alloc a mbuf */
@@ -384,6 +385,11 @@ testclone_testupdate_testdetach(void)
if (*data != MAGIC_DATA)
GOTO_FAIL("invalid data in clone->next\n");
+ if (rte_pktmbuf_seg_is_shared(m) == 0)
+ GOTO_FAIL("m should be marked as shared\n");
+ if (rte_pktmbuf_seg_is_shared(clone) == 0)
+ GOTO_FAIL("clone should be marked as shared\n");
+
if (rte_mbuf_refcnt_read(m) != 2)
GOTO_FAIL("invalid refcnt in m\n");
@@ -410,14 +416,32 @@ testclone_testupdate_testdetach(void)
if (rte_mbuf_refcnt_read(m->next) != 3)
GOTO_FAIL("invalid refcnt in m->next\n");
+ /* prepend data to one of the clone */
+ m2 = rte_pktmbuf_alloc(pktmbuf_pool);
+ if (m2 == NULL)
+ GOTO_FAIL("cannot allocate m2");
+ rte_pktmbuf_append(m2, sizeof(uint32_t));
+ rte_pktmbuf_chain(m2, clone);
+ clone = NULL;
+
+ if (rte_pktmbuf_data_is_shared(m2, 0, sizeof(uint32_t)))
+ GOTO_FAIL("m2 headers should not be marked as shared");
+ if (rte_pktmbuf_data_is_shared(m2, sizeof(uint32_t),
+ rte_pktmbuf_pkt_len(m2) - sizeof(uint32_t)) == 0)
+ GOTO_FAIL("m2 data should be marked as shared");
+
/* free mbuf */
rte_pktmbuf_free(m);
- rte_pktmbuf_free(clone);
- rte_pktmbuf_free(clone2);
-
m = NULL;
- clone = NULL;
+ rte_pktmbuf_free(m2);
+ m2 = NULL;
+
+ if (rte_pktmbuf_seg_is_shared(clone2))
+ GOTO_FAIL("clone2 should not be marked as shared\n");
+
+ rte_pktmbuf_free(clone2);
clone2 = NULL;
+
printf("%s ok\n", __func__);
return 0;
@@ -428,6 +452,8 @@ testclone_testupdate_testdetach(void)
rte_pktmbuf_free(clone);
if (clone2)
rte_pktmbuf_free(clone2);
+ if (m2)
+ rte_pktmbuf_free(m2);
return -1;
}
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 14956f6..cd77a56 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -576,7 +576,7 @@ rte_mbuf_data_dma_addr_default(const struct rte_mbuf *mb)
* The address of the direct mbuf corresponding to buffer_addr.
*/
static inline struct rte_mbuf *
-rte_mbuf_from_indirect(struct rte_mbuf *mi)
+rte_mbuf_from_indirect(const struct rte_mbuf *mi)
{
return (struct rte_mbuf *)RTE_PTR_SUB(mi->buf_addr, sizeof(*mi) +
mi->priv_size);
}
@@ -1574,6 +1574,75 @@ static inline int rte_pktmbuf_is_contiguous(const struct
rte_mbuf *m)
}
/**
+ * Test if a mbuf segment is shared
+ *
+ * Return true if the data embedded in this segment is shared by several
+ * mbufs. In this case, the mbuf data should be considered as read-only.
+ *
+ * @param m
+ * The packet mbuf.
+ * @return
+ * - (1), the mbuf segment is shared (read-only)
+ * - (0), the mbuf segment is not shared (writable)
+ */
+static inline int rte_pktmbuf_seg_is_shared(const struct rte_mbuf *m)
+{
+ if (rte_mbuf_refcnt_read(m) > 1)
+ return 1;
+
+ if (RTE_MBUF_INDIRECT(m) &&
+ rte_mbuf_refcnt_read(rte_mbuf_from_indirect(m)) > 1)
+ return 1;
+
+ return 0;
+}
+
+/**
+ * Test if some data in an mbuf chain is shared
+ *
+ * Return true if the specified data area in the mbuf chain is shared by
+ * several mbufs. In this case, this data should be considered as
+ * read-only.
+ *
+ * If the area described by off and len exceeds the bounds of the mbuf
+ * chain (off + len <= rte_pktmbuf_pkt_len()), the exceeding part of the
+ * area is ignored.
+ *
+ * @param m
+ * The packet mbuf.
+ * @return
+ * - (1), the mbuf data is shared (read-only)
+ * - (0), the mbuf data is not shared (writable)
+ */
+static inline int rte_pktmbuf_data_is_shared(const struct rte_mbuf *m,
+ uint32_t off, uint32_t len)
+{
+ const struct rte_mbuf *seg = m;
+
+ if (likely(off + len <= rte_pktmbuf_data_len(seg)))
+ return rte_pktmbuf_seg_is_shared(seg);
+
+ while (seg->next && off >= rte_pktmbuf_data_len(seg)) {
+ off -= rte_pktmbuf_data_len(seg);
+ seg = seg->next;
+ }
+
+ if (off + len <= rte_pktmbuf_data_len(seg))
+ return rte_pktmbuf_seg_is_shared(seg);
+
+ while (seg->next && len > 0) {
+ if (rte_pktmbuf_seg_is_shared(seg))
+ return 1;
+
+ len -= (rte_pktmbuf_data_len(seg) - off);
+ off = 0;
+ seg = seg->next;
+ }
+
+ return 0;
+}
+
+/**
* @internal used by rte_pktmbuf_read().
*/
void *__rte_pktmbuf_read(const struct rte_mbuf *m, uint32_t off,
--
2.8.1
