[uml-devel] Re: problems with UML, issues with includes

[Chris Friesen <cfriesen@nortelnetworks.com>]

Jeff Dike wrote:
> cfriesen@nortelnetworks.com said:
> 
>>#1  0xa00d03d6 in activate_fd (irq=3, fd=47, type=1,
>>dev_id=0xa02309f8) at irq_user.c:230 
>>
> 
> Why don't your line numbers match mine?  

I've added debug statements.

The kfree you seem to be talking
> about is this:

> 
>    211   out_unlock:
>    212          irq_unlock(flags);
>    213          kfree(new_fd);
>    214   out:
> 
> And I totally don't see a problem there.  new_fd isn't on any lists when it's
> freed there.

As mentioned in my other message, I'm seeing um_kmalloc() return a 
new_fd address that is *already* on the active_fds list.  Hence it ends 
up looking like a dupe, hence we end up calling kfree() on an address 
that is still on the active_fds list.

I made the following changes within activate_fd() to try and see what's 
going on.  If I set a breakpoint at the "redo=1" line and then step 
through the code, I end up in a continuous loop getting the same value 
for the return code of um_kmalloc().  There's something fishy going on 
here....

get_mem:
	new_fd = um_kmalloc(sizeof(*new_fd));	
	err = -ENOMEM;
	if(new_fd == NULL)
		goto out;
	
	redo = 0;
	flags = irq_lock();
	for(irq_fd = active_fds; irq_fd != NULL; irq_fd = irq_fd->next){
		
		if (irq_fd == new_fd) {
			redo = 1;
		}
	}
	irq_unlock(flags);
	
	if (redo)
		goto get_mem;


Chris


-- 
Chris Friesen                    | MailStop: 043/33/F10
Nortel Networks                  | work: (613) 765-0557
3500 Carling Avenue              | fax:  (613) 765-2986
Nepean, ON K2H 8E9 Canada        | email: cfriesen@nortelnetworks.com



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