SiS900 driver multicast problems and patch.

SiS900 driver multicast problems and patch.

[Lars Knudsen]

After upgrading to kernel 2.4.22 we discovered that multicast was no 
longer handled properly by the SiS900. Examining the changes between 
2.4.19 and 2.4.22 it is clear that the handling of multicast was changed 
but a bug was introduced.

A simple set_bit call from 2.4.19 was changed to the following:

u16 mc_filter[16] = {0};

unsigned int bit_nr =
         sis900_mcast_bitnr(mclist->dmi_addr, revision);
          mc_filter[bit_nr >> 4] |= (1 << bit_nr);

This will not work for bit_nr larger than 16 and hence the failure. 
Reverting to use set_bit causes multicast to be handled properly.

\Lars Knudsen

--- sis900.c    Mon Oct 27 17:49:36 2003
+++ sis900.c.orig       Mon Oct 27 17:48:52 2003
@@ -2101,8 +2101,9 @@
                rx_mode = RFAAB;
                for (i = 0, mclist = net_dev->mc_list; mclist && i < 
net_dev->mc_count;
                     i++, mclist = mclist->next) {
-                       set_bit(sis900_mcast_bitnr(mclist->dmi_addr, 
revision),
-                               mc_filter);
+                       unsigned int bit_nr =
+                               sis900_mcast_bitnr(mclist->dmi_addr, 
revision);
+                       mc_filter[bit_nr >> 4] |= (1 << bit_nr);
                }
        }

Re: SiS900 driver multicast problems and patch.

[Måns Rullgård]

Lars Knudsen <gandalf@revicon.com> writes:

> After upgrading to kernel 2.4.22 we discovered that multicast was no
> longer handled properly by the SiS900. Examining the changes between
> 2.4.19 and 2.4.22 it is clear that the handling of multicast was
> changed but a bug was introduced.

Your patch is broken.  Long lines are wrapped, tabs are converted to
spaces and it is reversed.

-- 
Måns Rullgård
mru@kth.se

Re: SiS900 driver multicast problems and patch.

[Lars Knudsen]

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Måns Rullgård wrote:

>Lars Knudsen <gandalf@revicon.com> writes:
>
>  
>
>>After upgrading to kernel 2.4.22 we discovered that multicast was no
>>longer handled properly by the SiS900. Examining the changes between
>>2.4.19 and 2.4.22 it is clear that the handling of multicast was
>>changed but a bug was introduced.
>>    
>>
>
>Your patch is broken.  Long lines are wrapped, tabs are converted to
>spaces and it is reversed.
>  
>
Ah, the wonders of cut and paste and a mail program trying to be helpfull.
Here is an updated version. Sorry for the extra noise.

\Lars Knudsen

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[-- Type: text/plain, Size: 448 bytes --]

--- sis900.c.orig	Mon Oct 27 17:48:52 2003
+++ sis900.c	Mon Oct 27 17:49:36 2003
@@ -2101,9 +2101,8 @@
 		rx_mode = RFAAB;
 		for (i = 0, mclist = net_dev->mc_list; mclist && i < net_dev->mc_count;
 		     i++, mclist = mclist->next) {
-			unsigned int bit_nr =
-				sis900_mcast_bitnr(mclist->dmi_addr, revision);
-			mc_filter[bit_nr >> 4] |= (1 << bit_nr);
+			set_bit(sis900_mcast_bitnr(mclist->dmi_addr, revision),
+				mc_filter);
 		}
 	}