From c738bfc506af1feaff2f138534bb5fc99da7e042 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Sun, 31 Jan 2021 12:46:57 -0500 Subject: [PATCH] cxgb(4): Remove assumption of physically contiguous mbufs. Investigation of iSCSI target data corruption reports brought me to discovery that cxgb(4) expects mbufs to be physically contiguous, that is not true after I've started using m_extaddref() in software iSCSI for large zero-copy transmissions. In case of fragmented memory the driver transmitted garbage from pages following the first one due to simple use of pmap_kextract() for the first pointer instead of proper bus_dmamap_load_mbuf_sg(). Seems like it was done as some optimization many years ago, and at very least it is wrong in a world of IOMMUs. This patch just removes that optimization, plus limits packet coalescing for mbufs crossing page boundary, also depending on assumption of one segment per packet. Sponsored by: iXsystems, Inc. (cherry picked from commit 9dc7c250b8bd2d5e669c7633e189a700a02c0571) --- sys/dev/cxgb/cxgb_sge.c | 3 ++- sys/dev/cxgb/sys/mvec.h | 14 -------------- sys/dev/cxgb/sys/uipc_mvec.c | 24 +++--------------------- 3 files changed, 5 insertions(+), 36 deletions(-) diff --git a/sys/dev/cxgb/cxgb_sge.c b/sys/dev/cxgb/cxgb_sge.c index 7f456ccff4c..491d1a751f4 100644 --- a/sys/dev/cxgb/cxgb_sge.c +++ b/sys/dev/cxgb/cxgb_sge.c @@ -322,7 +322,8 @@ coalesce_check(struct mbuf *m, void *arg) int *nbytes = &ci->nbytes; if ((*nbytes == 0) || ((*nbytes + m->m_len <= 10500) && - (*count < 7) && (m->m_next == NULL))) { + (*count < 7) && (m->m_next == NULL) && + ((mtod(m, vm_offset_t) & PAGE_MASK) + m->m_len <= PAGE_SIZE))) { *count += 1; *nbytes += m->m_len; return (1); diff --git a/sys/dev/cxgb/sys/mvec.h b/sys/dev/cxgb/sys/mvec.h index bdd0b55c548..4989bff29ec 100644 --- a/sys/dev/cxgb/sys/mvec.h +++ b/sys/dev/cxgb/sys/mvec.h @@ -33,20 +33,6 @@ #define _MVEC_H_ #include -static __inline void -busdma_map_mbuf_fast(bus_dma_tag_t tag, bus_dmamap_t map, - struct mbuf *m, bus_dma_segment_t *seg) -{ -#if defined(__i386__) || defined(__amd64__) - seg->ds_addr = pmap_kextract(mtod(m, vm_offset_t)); - seg->ds_len = m->m_len; -#else - int nsegstmp; - - bus_dmamap_load_mbuf_sg(tag, map, m, seg, &nsegstmp, 0); -#endif -} - int busdma_map_sg_collapse(bus_dma_tag_t tag, bus_dmamap_t map, struct mbuf **m, bus_dma_segment_t *segs, int *nsegs); void busdma_map_sg_vec(bus_dma_tag_t tag, bus_dmamap_t map, diff --git a/sys/dev/cxgb/sys/uipc_mvec.c b/sys/dev/cxgb/sys/uipc_mvec.c index ca31cf1897c..02f43707946 100644 --- a/sys/dev/cxgb/sys/uipc_mvec.c +++ b/sys/dev/cxgb/sys/uipc_mvec.c @@ -65,26 +65,7 @@ busdma_map_sg_collapse(bus_dma_tag_t tag, bus_dmamap_t map, retry: psegs = segs; seg_count = 0; - if (n->m_next == NULL) { - busdma_map_mbuf_fast(tag, map, n, segs); - *nsegs = 1; - return (0); - } -#if defined(__i386__) || defined(__amd64__) - while (n && seg_count < TX_MAX_SEGS) { - /* - * firmware doesn't like empty segments - */ - if (__predict_true(n->m_len != 0)) { - seg_count++; - busdma_map_mbuf_fast(tag, map, n, psegs); - psegs++; - } - n = n->m_next; - } -#else err = bus_dmamap_load_mbuf_sg(tag, map, *m, segs, &seg_count, 0); -#endif if (seg_count == 0) { if (cxgb_debug) printf("empty segment chain\n"); @@ -117,8 +98,9 @@ void busdma_map_sg_vec(bus_dma_tag_t tag, bus_dmamap_t map, struct mbuf *m, bus_dma_segment_t *segs, int *nsegs) { + int n = 0; - for (*nsegs = 0; m != NULL ; segs++, *nsegs += 1, m = m->m_nextpkt) - busdma_map_mbuf_fast(tag, map, m, segs); + for (*nsegs = 0; m != NULL; segs += n, *nsegs += n, m = m->m_nextpkt) + bus_dmamap_load_mbuf_sg(tag, map, m, segs, &n, 0); }