The rte_pktmbuf_detach() function should decrease refcnt on a direct
buffer.
Signed-off-by: Hiroyuki Mikita <h.mikita89 at gmail.com>
---
v4:
* fixed formatting.
* fixed doxygen comments of rte_pktmbuf_detach() to be clearer.
v3:
* fixed rte_pktmbuf_detach() to decrease refcnt.
* free the direct mbuf when refcnt becomes 0.
* added this issue to Resolved Issues in release notes.
v2:
* introduced a new function rte_pktmbuf_detach2() which decrease refcnt.
* marked rte_pktmbuf_detach() as deprecated.
* added comments about refcnt to rte_pktmbuf_attach() and rte_pktmbuf_detach().
* checked refcnt when detaching in unit tests.
* added this issue to release notes.
app/test/test_mbuf.c | 4 ++++
doc/guides/rel_notes/release_16_07.rst | 6 ++++++
lib/librte_mbuf/rte_mbuf.h | 23 ++++++++++++-----------
3 files changed, 22 insertions(+), 11 deletions(-)
diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c
index 98ff93a..8460db7 100644
--- a/app/test/test_mbuf.c
+++ b/app/test/test_mbuf.c
@@ -511,10 +511,14 @@ test_attach_from_different_pool(void)
rte_pktmbuf_detach(clone);
if (c_data != rte_pktmbuf_mtod(clone, char *))
GOTO_FAIL("clone was not detached properly\n");
+ if (rte_mbuf_refcnt_read(m) != 2)
+ GOTO_FAIL("invalid refcnt in m\n");
rte_pktmbuf_detach(clone2);
if (c_data2 != rte_pktmbuf_mtod(clone2, char *))
GOTO_FAIL("clone2 was not detached properly\n");
+ if (rte_mbuf_refcnt_read(m) != 1)
+ GOTO_FAIL("invalid refcnt in m\n");
/* free the clones and the initial mbuf */
rte_pktmbuf_free(clone2);
diff --git a/doc/guides/rel_notes/release_16_07.rst
b/doc/guides/rel_notes/release_16_07.rst
index 58c8ef9..a8c50c8 100644
--- a/doc/guides/rel_notes/release_16_07.rst
+++ b/doc/guides/rel_notes/release_16_07.rst
@@ -69,6 +69,12 @@ Drivers
Libraries
~~~~~~~~~
+* **mbuf: Fixed refcnt update when detaching.**
+
+ Fix the ``rte_pktmbuf_detach()`` function to decrement the direct
+ mbuf's reference counter. The previous behavior was not to affect
+ the reference counter. It lead a memory leak of the direct mbuf.
+
Examples
~~~~~~~~
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 7b92b88..48911a6 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1412,6 +1412,8 @@ static inline int rte_pktmbuf_alloc_bulk(struct
rte_mempool *pool,
*
* After attachment we refer the mbuf we attached as 'indirect',
* while mbuf we attached to as 'direct'.
+ * The direct mbuf's reference counter is incremented.
+ *
* Right now, not supported:
* - attachment for already indirect mbuf (e.g. - mi has to be direct).
* - mbuf we trying to attach (mi) is used by someone else
@@ -1465,13 +1467,17 @@ static inline void rte_pktmbuf_attach(struct rte_mbuf
*mi, struct rte_mbuf *m)
*
* - restore original mbuf address and length values.
* - reset pktmbuf data and data_len to their default values.
- * All other fields of the given packet mbuf will be left intact.
+ * - decrement the direct mbuf's reference counter. When the
+ * reference counter becomes 0, the direct mbuf is freed.
+ *
+ * All other fields of the given packet mbuf will be left intact.
*
* @param m
* The indirect attached packet mbuf.
*/
static inline void rte_pktmbuf_detach(struct rte_mbuf *m)
{
+ struct rte_mbuf *md = rte_mbuf_from_indirect(m);
struct rte_mempool *mp = m->pool;
uint32_t mbuf_size, buf_len, priv_size;
@@ -1486,6 +1492,9 @@ static inline void rte_pktmbuf_detach(struct rte_mbuf *m)
m->data_off = RTE_MIN(RTE_PKTMBUF_HEADROOM, (uint16_t)m->buf_len);
m->data_len = 0;
m->ol_flags = 0;
+
+ if (rte_mbuf_refcnt_update(md, -1) == 0)
+ __rte_mbuf_raw_free(md);
}
static inline struct rte_mbuf* __attribute__((always_inline))
@@ -1494,17 +1503,9 @@ __rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
__rte_mbuf_sanity_check(m, 0);
if (likely(rte_mbuf_refcnt_update(m, -1) == 0)) {
-
- /* if this is an indirect mbuf, then
- * - detach mbuf
- * - free attached mbuf segment
- */
- if (RTE_MBUF_INDIRECT(m)) {
- struct rte_mbuf *md = rte_mbuf_from_indirect(m);
+ /* if this is an indirect mbuf, it is detached. */
+ if (RTE_MBUF_INDIRECT(m))
rte_pktmbuf_detach(m);
- if (rte_mbuf_refcnt_update(md, -1) == 0)
- __rte_mbuf_raw_free(md);
- }
return m;
}
return NULL;
--
1.9.1
