Driver patch to look at...

[Randall Stewart]

Hmm

wait, I could probably do the compare to whats in the ring buffer ;-D

R
On Feb 5, 2013, at 2:04 PM, Randall Stewart wrote:

> Hmm
> 
> That would trade off a stack pointer + a compare
> vs always doing the move.
> 
> Thats fine until I have to add the _mc() version, then the put
> back would be an atomic, and most of the time the return from
> this is probably not changed…
> 
> I really would prefer not to since the compare and maybe store vs
> the always store.. though the same now, would be far more expensive
> in the _mc version.. if we do a _mc version of course ;-)
> 
> But I am willing to do whatever .. since this really needs to be fixed.
> 
> R
> On Feb 5, 2013, at 1:52 PM, John Baldwin wrote:
> 
>> On Tuesday, February 05, 2013 12:44:01 pm Randall Stewart wrote:
>>> Actually, no it is used.
>>> 
>>> If you look in if_var.h int he drbr_putback() function, it does
>>> a buf_ring_swap when the old mbuf pointer does not equal the
>>> new mbuf pointer. This *does* happen, I crashed at least once
>>> yesterday when the igb driver did something to free the original
>>> mbuf and return a new mbuf with the data (prepend or some such).
>>> 
>>> I also have found several issues that I have fixed this morning.. its been
>>> crash city on my test beds..
>>> 
>>> Here is the latest patch with all fixes and suggested changes from emaste 
>> (thanks Ed)
>> 
>> Actually, one more suggestion then (since you have to keep putback).  It
>> would be nice to not have to require 'snext' in all the callers.  How
>> about replace buf_ring_swap() with a buf_ring_putback_sc() that accepts the
>> mbuf and just stores it at the head unconditionally and have drbr_putback()
>> use that?
>> 
>> -- 
>> John Baldwin
>> _______________________________________________
>> freebsd-net at freebsd.org mailing list
>> http://lists.freebsd.org/mailman/listinfo/freebsd-net
>> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>> 
> 
> ------------------------------
> Randall Stewart
> 803-317-4952 (cell)
> 
> _______________________________________________
> freebsd-net at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
> 

------------------------------
Randall Stewart
803-317-4952 (cell)