[dpdk-dev] [PATCH v3] mbuf: decrease refcnt when detaching
Hiroyuki Mikita
h.mikita89 at gmail.com
Tue May 17 18:35:02 CEST 2016
The rte_pktmbuf_detach() function should decrease refcnt on a direct
buffer.
Signed-off-by: Hiroyuki Mikita <h.mikita89 at gmail.com>
---
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 | 17 ++++++++++-------
3 files changed, 20 insertions(+), 7 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 f6d543c..8283373 100644
--- a/doc/guides/rel_notes/release_16_07.rst
+++ b/doc/guides/rel_notes/release_16_07.rst
@@ -65,6 +65,12 @@ 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 529debb..299b60e 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1408,6 +1408,8 @@ 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
@@ -1462,12 +1464,15 @@ 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.
*
* @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;
@@ -1482,6 +1487,10 @@ 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))
@@ -1491,15 +1500,9 @@ __rte_pktmbuf_prefree_seg(struct rte_mbuf *m)
if (likely(rte_mbuf_refcnt_update(m, -1) == 0)) {
- /* if this is an indirect mbuf, then
- * - detach mbuf
- * - free attached mbuf segment
- */
+ /* if this is an indirect mbuf, it is detached. */
if (RTE_MBUF_INDIRECT(m)) {
- struct rte_mbuf *md = rte_mbuf_from_indirect(m);
rte_pktmbuf_detach(m);
- if (rte_mbuf_refcnt_update(md, -1) == 0)
- __rte_mbuf_raw_free(md);
}
return m;
}
--
1.9.1
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