hyperv/hn: Use buf_ring for txdesc list
So one spinlock is avoided, which would be potentially dangerous for virtual machine, if the spinlock holder was scheduled out by the host, as noted by royger. Old spinlock based txdesc list is still kept around, so we could have a safe fallback. No performance regression nor improvement is observed. Reviewed by: adrian Approved by: adrian (mentor) MFC after: 1 week Sponsored by: Microsoft OSTC Differential Revision: https://reviews.freebsd.org/D5290
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@ -58,6 +58,8 @@
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#include <dev/hyperv/include/hyperv.h>
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#define HN_USE_TXDESC_BUFRING
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MALLOC_DECLARE(M_NETVSC);
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#define NVSP_INVALID_PROTOCOL_VERSION (0xFFFFFFFF)
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@ -990,8 +992,12 @@ typedef struct {
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hv_bool_uint8_t link_state;
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} netvsc_device_info;
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#ifndef HN_USE_TXDESC_BUFRING
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struct hn_txdesc;
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SLIST_HEAD(hn_txdesc_list, hn_txdesc);
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#else
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struct buf_ring;
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#endif
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struct hn_rx_ring {
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struct lro_ctrl hn_lro;
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@ -1012,8 +1018,12 @@ struct hn_rx_ring {
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#define HN_TRUST_HCSUM_UDP 0x0004
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struct hn_tx_ring {
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#ifndef HN_USE_TXDESC_BUFRING
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struct mtx hn_txlist_spin;
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struct hn_txdesc_list hn_txlist;
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#else
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struct buf_ring *hn_txdesc_br;
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#endif
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int hn_txdesc_cnt;
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int hn_txdesc_avail;
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int hn_txeof;
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@ -70,6 +70,7 @@ __FBSDID("$FreeBSD$");
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#include <sys/lock.h>
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#include <sys/sx.h>
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#include <sys/sysctl.h>
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#include <sys/buf_ring.h>
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#include <net/if.h>
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#include <net/if_arp.h>
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@ -151,7 +152,9 @@ __FBSDID("$FreeBSD$");
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#define HN_DIRECT_TX_SIZE_DEF 128
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struct hn_txdesc {
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#ifndef HN_USE_TXDESC_BUFRING
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SLIST_ENTRY(hn_txdesc) link;
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#endif
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struct mbuf *m;
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struct hn_tx_ring *txr;
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int refs;
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@ -258,6 +261,14 @@ SYSCTL_INT(_hw_hn, OID_AUTO, share_tx_taskq, CTLFLAG_RDTUN,
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static struct taskqueue *hn_tx_taskq;
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#ifndef HN_USE_TXDESC_BUFRING
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static int hn_use_txdesc_bufring = 0;
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#else
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static int hn_use_txdesc_bufring = 1;
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#endif
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SYSCTL_INT(_hw_hn, OID_AUTO, use_txdesc_bufring, CTLFLAG_RD,
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&hn_use_txdesc_bufring, 0, "Use buf_ring for TX descriptors");
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/*
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* Forward declarations
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*/
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@ -570,6 +581,7 @@ hn_txdesc_put(struct hn_tx_ring *txr, struct hn_txdesc *txd)
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txd->flags |= HN_TXD_FLAG_ONLIST;
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#ifndef HN_USE_TXDESC_BUFRING
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mtx_lock_spin(&txr->hn_txlist_spin);
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KASSERT(txr->hn_txdesc_avail >= 0 &&
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txr->hn_txdesc_avail < txr->hn_txdesc_cnt,
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@ -577,6 +589,10 @@ hn_txdesc_put(struct hn_tx_ring *txr, struct hn_txdesc *txd)
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txr->hn_txdesc_avail++;
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SLIST_INSERT_HEAD(&txr->hn_txlist, txd, link);
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mtx_unlock_spin(&txr->hn_txlist_spin);
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#else
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atomic_add_int(&txr->hn_txdesc_avail, 1);
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buf_ring_enqueue(txr->hn_txdesc_br, txd);
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#endif
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return 1;
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}
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@ -586,6 +602,7 @@ hn_txdesc_get(struct hn_tx_ring *txr)
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{
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struct hn_txdesc *txd;
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#ifndef HN_USE_TXDESC_BUFRING
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mtx_lock_spin(&txr->hn_txlist_spin);
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txd = SLIST_FIRST(&txr->hn_txlist);
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if (txd != NULL) {
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@ -595,8 +612,14 @@ hn_txdesc_get(struct hn_tx_ring *txr)
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SLIST_REMOVE_HEAD(&txr->hn_txlist, link);
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}
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mtx_unlock_spin(&txr->hn_txlist_spin);
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#else
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txd = buf_ring_dequeue_sc(txr->hn_txdesc_br);
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#endif
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if (txd != NULL) {
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#ifdef HN_USE_TXDESC_BUFRING
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atomic_subtract_int(&txr->hn_txdesc_avail, 1);
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#endif
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KASSERT(txd->m == NULL && txd->refs == 0 &&
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(txd->flags & HN_TXD_FLAG_ONLIST), ("invalid txd"));
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txd->flags &= ~HN_TXD_FLAG_ONLIST;
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@ -2048,13 +2071,20 @@ hn_create_tx_ring(struct hn_softc *sc, int id)
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txr->hn_sc = sc;
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#ifndef HN_USE_TXDESC_BUFRING
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mtx_init(&txr->hn_txlist_spin, "hn txlist", NULL, MTX_SPIN);
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#endif
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mtx_init(&txr->hn_tx_lock, "hn tx", NULL, MTX_DEF);
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txr->hn_txdesc_cnt = HN_TX_DESC_CNT;
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txr->hn_txdesc = malloc(sizeof(struct hn_txdesc) * txr->hn_txdesc_cnt,
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M_NETVSC, M_WAITOK | M_ZERO);
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#ifndef HN_USE_TXDESC_BUFRING
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SLIST_INIT(&txr->hn_txlist);
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#else
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txr->hn_txdesc_br = buf_ring_alloc(txr->hn_txdesc_cnt, M_NETVSC,
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M_WAITOK, &txr->hn_tx_lock);
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#endif
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txr->hn_tx_taskq = sc->hn_tx_taskq;
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TASK_INIT(&txr->hn_start_task, 0, hn_start_taskfunc, txr);
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@ -2158,7 +2188,11 @@ hn_create_tx_ring(struct hn_softc *sc, int id)
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/* All set, put it to list */
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txd->flags |= HN_TXD_FLAG_ONLIST;
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#ifndef HN_USE_TXDESC_BUFRING
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SLIST_INSERT_HEAD(&txr->hn_txlist, txd, link);
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#else
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buf_ring_enqueue(txr->hn_txdesc_br, txd);
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#endif
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}
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txr->hn_txdesc_avail = txr->hn_txdesc_cnt;
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@ -2190,6 +2224,20 @@ hn_create_tx_ring(struct hn_softc *sc, int id)
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return 0;
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}
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static void
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hn_txdesc_dmamap_destroy(struct hn_txdesc *txd)
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{
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struct hn_tx_ring *txr = txd->txr;
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KASSERT(txd->m == NULL, ("still has mbuf installed"));
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KASSERT((txd->flags & HN_TXD_FLAG_DMAMAP) == 0, ("still dma mapped"));
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bus_dmamap_unload(txr->hn_tx_rndis_dtag, txd->rndis_msg_dmap);
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bus_dmamem_free(txr->hn_tx_rndis_dtag, txd->rndis_msg,
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txd->rndis_msg_dmap);
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bus_dmamap_destroy(txr->hn_tx_data_dtag, txd->data_dmap);
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}
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static void
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hn_destroy_tx_ring(struct hn_tx_ring *txr)
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{
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@ -2198,19 +2246,15 @@ hn_destroy_tx_ring(struct hn_tx_ring *txr)
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if (txr->hn_txdesc == NULL)
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return;
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#ifndef HN_USE_TXDESC_BUFRING
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while ((txd = SLIST_FIRST(&txr->hn_txlist)) != NULL) {
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KASSERT(txd->m == NULL, ("still has mbuf installed"));
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KASSERT((txd->flags & HN_TXD_FLAG_DMAMAP) == 0,
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("still dma mapped"));
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SLIST_REMOVE_HEAD(&txr->hn_txlist, link);
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bus_dmamap_unload(txr->hn_tx_rndis_dtag,
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txd->rndis_msg_dmap);
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bus_dmamem_free(txr->hn_tx_rndis_dtag,
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txd->rndis_msg, txd->rndis_msg_dmap);
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bus_dmamap_destroy(txr->hn_tx_data_dtag, txd->data_dmap);
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hn_txdesc_dmamap_destroy(txd);
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}
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#else
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while ((txd = buf_ring_dequeue_sc(txr->hn_txdesc_br)) != NULL)
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hn_txdesc_dmamap_destroy(txd);
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#endif
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if (txr->hn_tx_data_dtag != NULL)
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bus_dma_tag_destroy(txr->hn_tx_data_dtag);
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@ -2219,7 +2263,9 @@ hn_destroy_tx_ring(struct hn_tx_ring *txr)
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free(txr->hn_txdesc, M_NETVSC);
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txr->hn_txdesc = NULL;
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#ifndef HN_USE_TXDESC_BUFRING
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mtx_destroy(&txr->hn_txlist_spin);
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#endif
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mtx_destroy(&txr->hn_tx_lock);
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}
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