Author: arybchik Date: Fri May 15 06:50:59 2015 New Revision: 282942 URL: https://svnweb.freebsd.org/changeset/base/282942
Log: sfxge: split sfxge_tx_qdpl_put() into *_locked() and *_unlocked() It simplifies understanding of the sfxge_tx_packet_add() logic and avoids passing of 'locked' to called function. Reviewed by: gnn Sponsored by: Solarflare Communications, Inc. MFC after: 2 days Differential Revision: https://reviews.freebsd.org/D2547 Modified: head/sys/dev/sfxge/sfxge_tx.c head/sys/dev/sfxge/sfxge_tx.h Modified: head/sys/dev/sfxge/sfxge_tx.c ============================================================================== --- head/sys/dev/sfxge/sfxge_tx.c Fri May 15 06:49:43 2015 (r282941) +++ head/sys/dev/sfxge/sfxge_tx.c Fri May 15 06:50:59 2015 (r282942) @@ -521,18 +521,10 @@ sfxge_tx_qdpl_service(struct sfxge_txq * } /* - * Put a packet on the deferred packet list. - * - * If we are called with the txq lock held, we put the packet on the "get - * list", otherwise we atomically push it on the "put list". The swizzle - * function takes care of ordering. - * - * The length of the put list is bounded by SFXGE_TX_MAX_DEFERRED. We - * overload the csum_data field in the mbuf to keep track of this length - * because there is no cheap alternative to avoid races. + * Put a packet on the deferred packet get-list. */ static int -sfxge_tx_qdpl_put(struct sfxge_txq *txq, struct mbuf *mbuf, int locked) +sfxge_tx_qdpl_put_locked(struct sfxge_txq *txq, struct mbuf *mbuf) { struct sfxge_tx_dpl *stdp; @@ -540,52 +532,66 @@ sfxge_tx_qdpl_put(struct sfxge_txq *txq, KASSERT(mbuf->m_nextpkt == NULL, ("mbuf->m_nextpkt != NULL")); - if (locked) { - SFXGE_TXQ_LOCK_ASSERT_OWNED(txq); - - sfxge_tx_qdpl_swizzle(txq); + SFXGE_TXQ_LOCK_ASSERT_OWNED(txq); - if (stdp->std_get_count >= stdp->std_get_max) { - txq->get_overflow++; + if (stdp->std_get_count >= stdp->std_get_max) { + txq->get_overflow++; + return (ENOBUFS); + } + if (sfxge_is_mbuf_non_tcp(mbuf)) { + if (stdp->std_get_non_tcp_count >= + stdp->std_get_non_tcp_max) { + txq->get_non_tcp_overflow++; return (ENOBUFS); } - if (sfxge_is_mbuf_non_tcp(mbuf)) { - if (stdp->std_get_non_tcp_count >= - stdp->std_get_non_tcp_max) { - txq->get_non_tcp_overflow++; - return (ENOBUFS); - } - stdp->std_get_non_tcp_count++; - } - - *(stdp->std_getp) = mbuf; - stdp->std_getp = &mbuf->m_nextpkt; - stdp->std_get_count++; - } else { - volatile uintptr_t *putp; - uintptr_t old; - uintptr_t new; - unsigned old_len; - - putp = &stdp->std_put; - new = (uintptr_t)mbuf; - - do { - old = *putp; - if (old != 0) { - struct mbuf *mp = (struct mbuf *)old; - old_len = mp->m_pkthdr.csum_data; - } else - old_len = 0; - if (old_len >= stdp->std_put_max) { - atomic_add_long(&txq->put_overflow, 1); - return (ENOBUFS); - } - mbuf->m_pkthdr.csum_data = old_len + 1; - mbuf->m_nextpkt = (void *)old; - } while (atomic_cmpset_ptr(putp, old, new) == 0); + stdp->std_get_non_tcp_count++; } + *(stdp->std_getp) = mbuf; + stdp->std_getp = &mbuf->m_nextpkt; + stdp->std_get_count++; + + return (0); +} + +/* + * Put a packet on the deferred packet put-list. + * + * We overload the csum_data field in the mbuf to keep track of this length + * because there is no cheap alternative to avoid races. + */ +static int +sfxge_tx_qdpl_put_unlocked(struct sfxge_txq *txq, struct mbuf *mbuf) +{ + struct sfxge_tx_dpl *stdp; + volatile uintptr_t *putp; + uintptr_t old; + uintptr_t new; + unsigned old_len; + + KASSERT(mbuf->m_nextpkt == NULL, ("mbuf->m_nextpkt != NULL")); + + SFXGE_TXQ_LOCK_ASSERT_NOTOWNED(txq); + + stdp = &txq->dpl; + putp = &stdp->std_put; + new = (uintptr_t)mbuf; + + do { + old = *putp; + if (old != 0) { + struct mbuf *mp = (struct mbuf *)old; + old_len = mp->m_pkthdr.csum_data; + } else + old_len = 0; + if (old_len >= stdp->std_put_max) { + atomic_add_long(&txq->put_overflow, 1); + return (ENOBUFS); + } + mbuf->m_pkthdr.csum_data = old_len + 1; + mbuf->m_nextpkt = (void *)old; + } while (atomic_cmpset_ptr(putp, old, new) == 0); + return (0); } @@ -612,22 +618,29 @@ sfxge_tx_packet_add(struct sfxge_txq *tx */ locked = SFXGE_TXQ_TRYLOCK(txq); - if (sfxge_tx_qdpl_put(txq, m, locked) != 0) { - if (locked) + if (locked) { + /* First swizzle put-list to get-list to keep order */ + sfxge_tx_qdpl_swizzle(txq); + + rc = sfxge_tx_qdpl_put_locked(txq, m); + if (rc != 0) { SFXGE_TXQ_UNLOCK(txq); - rc = ENOBUFS; - goto fail; - } + goto fail; + } + } else { + rc = sfxge_tx_qdpl_put_unlocked(txq, m); + if (rc != 0) + goto fail; - /* - * Try to grab the lock again. - * - * If we are able to get the lock, we need to process the deferred - * packet list. If we are not able to get the lock, another thread - * is processing the list. - */ - if (!locked) + /* + * Try to grab the lock again. + * + * If we are able to get the lock, we need to process + * the deferred packet list. If we are not able to get + * the lock, another thread is processing the list. + */ locked = SFXGE_TXQ_TRYLOCK(txq); + } if (locked) { /* Try to service the list. */ Modified: head/sys/dev/sfxge/sfxge_tx.h ============================================================================== --- head/sys/dev/sfxge/sfxge_tx.h Fri May 15 06:49:43 2015 (r282941) +++ head/sys/dev/sfxge/sfxge_tx.h Fri May 15 06:50:59 2015 (r282942) @@ -148,6 +148,8 @@ enum sfxge_txq_type { mtx_unlock(&(_txq)->lock) #define SFXGE_TXQ_LOCK_ASSERT_OWNED(_txq) \ mtx_assert(&(_txq)->lock, MA_OWNED) +#define SFXGE_TXQ_LOCK_ASSERT_NOTOWNED(_txq) \ + mtx_assert(&(_txq)->lock, MA_NOTOWNED) struct sfxge_txq { _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
