Date: Wed, 16 Aug 2017 13:43:27 -0700 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Sean Bruno <sbruno@FreeBSD.org>, Matt Macy <matt@mattmacy.io> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r322338 - head/sys/net Message-ID: <20170816204327.GK1113@FreeBSD.org> In-Reply-To: <201708100343.v7A3hNwR068837@repo.freebsd.org> References: <201708100343.v7A3hNwR068837@repo.freebsd.org>
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Hi, On Thu, Aug 10, 2017 at 03:43:23AM +0000, Sean Bruno wrote: S> Author: sbruno S> Date: Thu Aug 10 03:43:23 2017 S> New Revision: 322338 S> URL: https://svnweb.freebsd.org/changeset/base/322338 S> S> Log: S> Don't leak mbufs if clusers exceeds the number of segments. This would S> leak mbufs over time causing crashes. S> S> PR: 221202 S> Submitted by: Matt Macy <matt@mattmacy.io> S> Reported by: gergely.czuczy@harmless.hu S> Sponsored by: Limelight Networks S> S> Modified: S> head/sys/net/iflib.c S> S> Modified: head/sys/net/iflib.c S> ============================================================================== S> --- head/sys/net/iflib.c Thu Aug 10 03:11:05 2017 (r322337) S> +++ head/sys/net/iflib.c Thu Aug 10 03:43:23 2017 (r322338) S> @@ -267,6 +267,8 @@ iflib_get_sctx(if_ctx_t ctx) S> #define RX_SW_DESC_INUSE (1 << 3) S> #define TX_SW_DESC_MAPPED (1 << 4) S> S> +#define M_TOOBIG M_UNUSED_8 If you DO use something, then please don't pretent it is unused. This creates mess, when someone else will look into sys/mbuf.h and find M_UNUSED_8 there clearly marked as available and will start using it. However, my reading of the change is that only packets in a TX ring are marked with this flag. And later they are checked in the same place, and they don't travel out of iflib. So, it is a local flag, and in this case you don't need to grab a global mbuf flag, and take any of the M_PROTO flags. S> typedef struct iflib_sw_rx_desc_array { S> bus_dmamap_t *ifsd_map; /* bus_dma maps for packet */ S> struct mbuf **ifsd_m; /* pkthdr mbufs */ S> @@ -2930,8 +2932,11 @@ iflib_busdma_load_mbuf_sg(iflib_txq_t txq, bus_dma_tag S> m = m->m_next; S> count++; S> } while (m != NULL); S> - if (count > *nsegs) S> + if (count > *nsegs) { S> + ifsd_m[pidx] = *m0; S> + ifsd_m[pidx]->m_flags |= M_TOOBIG; S> return (0); S> + } S> m = *m0; S> count = 0; S> do { S> @@ -3241,8 +3246,15 @@ iflib_tx_desc_free(iflib_txq_t txq, int n) S> if ((m = ifsd_m[cidx]) != NULL) { S> /* XXX we don't support any drivers that batch packets yet */ S> MPASS(m->m_nextpkt == NULL); S> - S> - m_free(m); S> + /* if the number of clusters exceeds the number of segments S> + * there won't be space on the ring to save a pointer to each S> + * cluster so we simply free the list here S> + */ S> + if (m->m_flags & M_TOOBIG) { S> + m_freem(m); S> + } else { S> + m_free(m); S> + } S> ifsd_m[cidx] = NULL; S> #if MEMORY_LOGGING S> txq->ift_dequeued++; Can you please explain the goal of the change? AFAIK, the problem could be fixed with one liner: - m_free(m); + m_freem(m); n the iflib_tx_desc_free(). -- Totus tuus, Glebius.
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