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Revision db61ecc3352d72513c1b07805bd6f760e30c001b authored by Tommy S. Christensen on 19 May 2005, 19:46:59 UTC, committed by David S. Miller on 19 May 2005, 19:46:59 UTC 
[NETLINK]: Fix race with recvmsg().
 
This bug causes:

assertion (!atomic_read(&sk->sk_rmem_alloc)) failed at net/netlink/af_netlink.c (122)

What's happening is that:

1) The skb is sent to socket 1.
2) Someone does a recvmsg on socket 1 and drops the ref on the skb.
   Note that the rmalloc is not returned at this point since the
   skb is still referenced.
3) The same skb is now sent to socket 2.

This version of the fix resurrects the skb_orphan call that was moved
out, last time we had 'shared-skb troubles'. It is practically a no-op
in the common case, but still prevents the possible race with recvmsg.

Signed-off-by: Tommy S. Christensen <tommy.christensen@tpack.net>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 1eda339
Raw File
mcabook.tmpl 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>

<book id="MCAGuide">
 <bookinfo>
  <title>MCA Driver Programming Interface</title>
  
  <authorgroup>
   <author>
    <firstname>Alan</firstname>
    <surname>Cox</surname>
    <affiliation>
     <address>
      <email>alan@redhat.com</email>
     </address>
    </affiliation>
   </author>
   <author>
    <firstname>David</firstname>
    <surname>Weinehall</surname>
   </author>
   <author>
    <firstname>Chris</firstname>
    <surname>Beauregard</surname>
   </author>
  </authorgroup>

  <copyright>
   <year>2000</year>
   <holder>Alan Cox</holder>
   <holder>David Weinehall</holder>
   <holder>Chris Beauregard</holder>
  </copyright>

  <legalnotice>
   <para>
     This documentation is free software; you can redistribute
     it and/or modify it under the terms of the GNU General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later
     version.
   </para>
      
   <para>
     This program is distributed in the hope that it will be
     useful, but WITHOUT ANY WARRANTY; without even the implied
     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     See the GNU General Public License for more details.
   </para>
      
   <para>
     You should have received a copy of the GNU General Public
     License along with this program; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
     MA 02111-1307 USA
   </para>
      
   <para>
     For more details see the file COPYING in the source
     distribution of Linux.
   </para>
  </legalnotice>
 </bookinfo>

<toc></toc>

  <chapter id="intro">
      <title>Introduction</title>
  <para>
	The MCA bus functions provide a generalised interface to find MCA
	bus cards, to claim them for a driver, and to read and manipulate POS 
	registers without being aware of the motherboard internals or 
	certain deep magic specific to onboard devices.
  </para>
  <para>
	The basic interface to the MCA bus devices is the slot. Each slot
	is numbered and virtual slot numbers are assigned to the internal
	devices. Using a pci_dev as other busses do does not really make
	sense in the MCA context as the MCA bus resources require card
	specific interpretation.
  </para>
  <para>
	Finally the MCA bus functions provide a parallel set of DMA
	functions mimicing the ISA bus DMA functions as closely as possible,
	although also supporting the additional DMA functionality on the
	MCA bus controllers.
  </para>
  </chapter>
  <chapter id="bugs">
     <title>Known Bugs And Assumptions</title>
  <para>
	None.	
  </para>
  </chapter>

  <chapter id="pubfunctions">
     <title>Public Functions Provided</title>
!Earch/i386/kernel/mca.c
  </chapter>

  <chapter id="dmafunctions">
     <title>DMA Functions Provided</title>
!Iinclude/asm-i386/mca_dma.h
  </chapter>

</book>
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