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Date:      Thu, 9 Jan 2014 04:26:39 +0400
From:      Gleb Smirnoff <glebius@FreeBSD.org>
To:        Eric Davis <edavis@FreeBSD.org>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org
Subject:   Re: svn commit: r260415 - head/sys/dev/bxe
Message-ID:  <20140109002639.GL71033@FreeBSD.org>
In-Reply-To: <201401072226.s07MQKqh026817@svn.freebsd.org>
References:  <201401072226.s07MQKqh026817@svn.freebsd.org>
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  Eric,

On Tue, Jan 07, 2014 at 10:26:20PM +0000, Eric Davis wrote:
E> Author: edavis
E> Date: Tue Jan  7 22:26:20 2014
E> New Revision: 260415
E> URL: http://svnweb.freebsd.org/changeset/base/260415
E> 
E> Log:
E>   defragment mbuf chains longer than hw segment limit before dropping
E>   
E>   Approved by:	davidch
E> 
E> Modified:
E>   head/sys/dev/bxe/bxe.c
E>   head/sys/dev/bxe/ecore_hsi.h
E> 
E> Modified: head/sys/dev/bxe/bxe.c
E> ==============================================================================
E> --- head/sys/dev/bxe/bxe.c	Tue Jan  7 21:25:18 2014	(r260414)
E> +++ head/sys/dev/bxe/bxe.c	Tue Jan  7 22:26:20 2014	(r260415)
E> @@ -34,7 +34,7 @@
E>  #include <sys/cdefs.h>
E>  __FBSDID("$FreeBSD$");
E>  
E> -#define BXE_DRIVER_VERSION "1.78.76"
E> +#define BXE_DRIVER_VERSION "1.78.77"
E>  
E>  #include "bxe.h"
E>  #include "ecore_sp.h"
E> @@ -5501,10 +5501,31 @@ bxe_tx_encap(struct bxe_fastpath *fp, st
E>              fp->eth_q_stats.tx_window_violation_std++;
E>          }
E>  
E> -        /* XXX I don't like this, change to double copy packet */
E> +        /* lets try to defragment this mbuf */
E> +        fp->eth_q_stats.mbuf_defrag_attempts++;
E>  
E> -        /* no sense trying to defrag again, just drop the frame */
E> -        rc = ENODEV;
E> +        m0 = m_defrag(*m_head, M_DONTWAIT);

It is already more than a decade as M_DONTWAIT shouldn't be used. Generic
malloc(9) flag of M_NOWAIT should be used.

I wonder, why did you use it in new code? Is that just through habit,
or do we still got somewhere outdated piece of documentation?

E> +        if (m0 == NULL) {
E> +            fp->eth_q_stats.mbuf_defrag_failures++;
E> +            /* Ugh, just drop the frame... :( */
E> +            rc = ENOBUFS;
E> +        } else {
E> +            /* defrag successful, try mapping again */
E> +            *m_head = m0;
E> +            error = bus_dmamap_load_mbuf_sg(fp->tx_mbuf_tag,
E> +                                            tx_buf->m_map, m0,
E> +                                            segs, &nsegs, BUS_DMA_NOWAIT);
E> +            if (error) {
E> +                fp->eth_q_stats.tx_dma_mapping_failure++;
E> +                /* No sense in trying to defrag/copy chain, drop it. :( */
E> +                rc = error;
E> +            }
E> +
E> +            /* if the chain is still too long then drop it */
E> +            if (__predict_false(nsegs > 12)) {
E> +                rc = ENODEV;
E> +            }
E> +        }
E>      }

-- 
Totus tuus, Glebius.

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