kern/154302: commit references a PR

[dfilter service]

The following reply was made to PR kern/154302; it has been noted by GNATS.

From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/154302: commit references a PR
Date: Tue, 31 Jan 2012 18:13:59 +0000 (UTC)

 Author: gibbs
 Date: Tue Jan 31 18:13:49 2012
 New Revision: 230831
 URL: http://svn.freebsd.org/changeset/base/230831
 
 Log:
   MFC r225708 into stable/8:
   
   Modify the netfront driver so it can successfully attach to
   PV devices with the ioemu attribute set.
   
   sys/dev/xen/netfront/netfront.c:
   	o If a mac address for the interface cannot be found
   	  in the front-side XenStore tree, look for an entry
   	  in the back-side tree.  With ioemu devices, the
   	  emulator does not populate the front side tree and
   	  neither does Xend.
   	o Return an error rather than panic when an attach
   	  attempt fails.
   
   Reported by:	Janne Snabb (fix inspired by patch provided)
   PR:		kern/154302
 
 Modified:
   stable/8/sys/dev/xen/netfront/netfront.c
 Directory Properties:
   stable/8/sys/   (props changed)
   stable/8/sys/amd64/include/xen/   (props changed)
   stable/8/sys/cddl/contrib/opensolaris/   (props changed)
   stable/8/sys/contrib/dev/acpica/   (props changed)
   stable/8/sys/contrib/pf/   (props changed)
 
 Modified: stable/8/sys/dev/xen/netfront/netfront.c
 ==============================================================================
 --- stable/8/sys/dev/xen/netfront/netfront.c	Tue Jan 31 17:51:30 2012	(r230830)
 +++ stable/8/sys/dev/xen/netfront/netfront.c	Tue Jan 31 18:13:49 2012	(r230831)
 @@ -402,11 +402,33 @@ xen_net_read_mac(device_t dev, uint8_t m
  {
  	int error, i;
  	char *s, *e, *macstr;
 +	const char *path;
  
 -	error = xs_read(XST_NIL, xenbus_get_node(dev), "mac", NULL,
 -	    (void **) &macstr);
 -	if (error)
 +	path = xenbus_get_node(dev);
 +	error = xs_read(XST_NIL, path, "mac", NULL, (void **) &macstr);
 +	if (error == ENOENT) {
 +		/*
 +		 * Deal with missing mac XenStore nodes on devices with
 +		 * HVM emulation (the 'ioemu' configuration attribute)
 +		 * enabled.
 +		 *
 +		 * The HVM emulator may execute in a stub device model
 +		 * domain which lacks the permission, only given to Dom0,
 +		 * to update the guest's XenStore tree.  For this reason,
 +		 * the HVM emulator doesn't even attempt to write the
 +		 * front-side mac node, even when operating in Dom0.
 +		 * However, there should always be a mac listed in the
 +		 * backend tree.  Fallback to this version if our query
 +		 * of the front side XenStore location doesn't find
 +		 * anything.
 +		 */
 +		path = xenbus_get_otherend_path(dev);
 +		error = xs_read(XST_NIL, path, "mac", NULL, (void **) &macstr);
 +	}
 +	if (error != 0) {
 +		xenbus_dev_fatal(dev, error, "parsing %s/mac", path);
  		return (error);
 +	}
  
  	s = macstr;
  	for (i = 0; i < ETHER_ADDR_LEN; i++) {
 @@ -447,7 +469,7 @@ netfront_attach(device_t dev)
  	err = create_netdev(dev);
  	if (err) {
  		xenbus_dev_fatal(dev, err, "creating netdev");
 -		return err;
 +		return (err);
  	}
  
  #if __FreeBSD_version >= 700000
 @@ -457,7 +479,7 @@ netfront_attach(device_t dev)
  	    &xn_enable_lro, 0, "Large Receive Offload");
  #endif
  
 -	return 0;
 +	return (0);
  }
  
  
 @@ -2020,11 +2042,8 @@ create_netdev(device_t dev)
  	}
  	
  	err = xen_net_read_mac(dev, np->mac);
 -	if (err) {
 -		xenbus_dev_fatal(dev, err, "parsing %s/mac",
 -		    xenbus_get_node(dev));
 +	if (err)
  		goto out;
 -	}
  	
  	/* Set up ifnet structure */
  	ifp = np->xn_ifp = if_alloc(IFT_ETHER);
 @@ -2066,8 +2085,7 @@ create_netdev(device_t dev)
  exit:
  	gnttab_free_grant_references(np->gref_tx_head);
  out:
 -	panic("do something smart");
 -
 +	return (err);
  }
  
  /**
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