From: Olivier Matz Date: Wed, 6 Jan 2021 13:33:33 +0000 (+0100) Subject: mbuf: fix reset on mbuf free X-Git-Url: http://git.droids-corp.org/?p=dpdk.git;a=commitdiff_plain;h=2741ec394382a797ecda7b8937f8420890152f90 mbuf: fix reset on mbuf free m->nb_seg must be reset on mbuf free whatever the value of m->next, because it can happen that m->nb_seg is != 1. For instance in this case: m1 = rte_pktmbuf_alloc(mp); rte_pktmbuf_append(m1, 500); m2 = rte_pktmbuf_alloc(mp); rte_pktmbuf_append(m2, 500); rte_pktmbuf_chain(m1, m2); m0 = rte_pktmbuf_alloc(mp); rte_pktmbuf_append(m0, 500); rte_pktmbuf_chain(m0, m1); As rte_pktmbuf_chain() does not reset nb_seg in the initial m1 segment (this is not required), after this code the mbuf chain have 3 segments: - m0: next=m1, nb_seg=3 - m1: next=m2, nb_seg=2 - m2: next=NULL, nb_seg=1 Then split this chain between m1 and m2, it would result in 2 packets: - first packet - m0: next=m1, nb_seg=2 - m1: next=NULL, nb_seg=2 - second packet - m2: next=NULL, nb_seg=1 Freeing the first packet will not restore nb_seg=1 in the second segment. This is an issue because it is expected that mbufs stored in pool have their nb_seg field set to 1. Fixes: 8f094a9ac5d7 ("mbuf: set mbuf fields while in pool") Cc: stable@dpdk.org Signed-off-by: Olivier Matz Acked-by: Morten Brørup Acked-by: Ajit Khaparde Acked-by: Konstantin Ananyev --- diff --git a/app/test/test_mbuf.c b/app/test/test_mbuf.c index a40f7d4883..1bc12c02dd 100644 --- a/app/test/test_mbuf.c +++ b/app/test/test_mbuf.c @@ -2677,6 +2677,63 @@ fail: return -1; } +/* check that m->nb_segs and m->next are reset on mbuf free */ +static int +test_nb_segs_and_next_reset(struct rte_mempool *pktmbuf_pool) +{ + struct rte_mbuf *m0 = NULL, *m1 = NULL, *m2 = NULL; + + /* alloc mbufs */ + m0 = rte_pktmbuf_alloc(pktmbuf_pool); + m1 = rte_pktmbuf_alloc(pktmbuf_pool); + m2 = rte_pktmbuf_alloc(pktmbuf_pool); + if (m0 == NULL || m1 == NULL || m2 == NULL) + GOTO_FAIL("Failed to allocate mbuf"); + + /* append data in all of them */ + if (rte_pktmbuf_append(m0, 500) == NULL || + rte_pktmbuf_append(m1, 500) == NULL || + rte_pktmbuf_append(m2, 500) == NULL) + GOTO_FAIL("Failed to append data in mbuf"); + + /* chain them in one mbuf m0 */ + rte_pktmbuf_chain(m1, m2); + rte_pktmbuf_chain(m0, m1); + if (m0->nb_segs != 3 || m0->next != m1 || m1->next != m2 || + m2->next != NULL) { + m1 = m2 = NULL; + GOTO_FAIL("Failed to chain mbufs"); + } + + /* split m0 chain in two, between m1 and m2 */ + m0->nb_segs = 2; + m1->next = NULL; + m2->nb_segs = 1; + + /* free the 2 mbuf chains m0 and m2 */ + rte_pktmbuf_free(m0); + rte_pktmbuf_free(m2); + + /* ensure that m->next and m->nb_segs are reset in freed mbufs */ + if (m0->nb_segs != 1 || m0->next != NULL || + m1->nb_segs != 1 || m1->next != NULL || + m2->nb_segs != 1 || m2->next != NULL) { + m0 = m1 = m2 = NULL; + GOTO_FAIL("nb_segs or next was not reset properly"); + } + + return 0; + +fail: + if (m0 != NULL) + rte_pktmbuf_free(m0); + if (m1 != NULL) + rte_pktmbuf_free(m1); + if (m2 != NULL) + rte_pktmbuf_free(m2); + return -1; +} + static int test_mbuf(void) { @@ -2867,6 +2924,11 @@ test_mbuf(void) goto err; } + /* test reset of m->nb_segs and m->next on mbuf free */ + if (test_nb_segs_and_next_reset(pktmbuf_pool) < 0) { + printf("test_nb_segs_and_next_reset() failed\n"); + goto err; + } ret = 0; err: diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c index 7d09ee2939..5f77840557 100644 --- a/lib/librte_mbuf/rte_mbuf.c +++ b/lib/librte_mbuf/rte_mbuf.c @@ -129,10 +129,10 @@ rte_pktmbuf_free_pinned_extmem(void *addr, void *opaque) rte_mbuf_ext_refcnt_set(m->shinfo, 1); m->ol_flags = EXT_ATTACHED_MBUF; - if (m->next != NULL) { + if (m->next != NULL) m->next = NULL; + if (m->nb_segs != 1) m->nb_segs = 1; - } rte_mbuf_raw_free(m); } diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h index c4c9ebfaa0..8c1097ed76 100644 --- a/lib/librte_mbuf/rte_mbuf.h +++ b/lib/librte_mbuf/rte_mbuf.h @@ -1340,10 +1340,10 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) return NULL; } - if (m->next != NULL) { + if (m->next != NULL) m->next = NULL; + if (m->nb_segs != 1) m->nb_segs = 1; - } return m; @@ -1357,10 +1357,10 @@ rte_pktmbuf_prefree_seg(struct rte_mbuf *m) return NULL; } - if (m->next != NULL) { + if (m->next != NULL) m->next = NULL; + if (m->nb_segs != 1) m->nb_segs = 1; - } rte_mbuf_refcnt_set(m, 1); return m; diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h index 567551deab..78a1fcc8ff 100644 --- a/lib/librte_mbuf/rte_mbuf_core.h +++ b/lib/librte_mbuf/rte_mbuf_core.h @@ -495,7 +495,12 @@ struct rte_mbuf { * or non-atomic) is controlled by the RTE_MBUF_REFCNT_ATOMIC flag. */ uint16_t refcnt; - uint16_t nb_segs; /**< Number of segments. */ + + /** + * Number of segments. Only valid for the first segment of an mbuf + * chain. + */ + uint16_t nb_segs; /** Input port (16 bits to support more than 256 virtual ports). * The event eth Tx adapter uses this field to specify the output port. @@ -591,7 +596,11 @@ struct rte_mbuf { /* second cache line - fields only used in slow path or on TX */ RTE_MARKER cacheline1 __rte_cache_min_aligned; - struct rte_mbuf *next; /**< Next segment of scattered packet. */ + /** + * Next segment of scattered packet. Must be NULL in the last segment or + * in case of non-segmented packet. + */ + struct rte_mbuf *next; /* fields to support TX offloads */ RTE_STD_C11