Re: kern/183227: commit references a PR

The following reply was made to PR kern/183227; it has been noted by GNATS.

From: [email protected] (dfilter service)
To: [email protected]
Cc:  
Subject: Re: kern/183227: commit references a PR
Date: Mon, 20 Jan 2014 18:37:47 +0000 (UTC)

 Author: marcel
 Date: Mon Jan 20 18:37:35 2014
 New Revision: 260914
 URL: http://svnweb.freebsd.org/changeset/base/260914
 
 Log:
   In pmap_set_pte(), make sure to enforce ordering by inserting a memory
   fence. Under system load, the CPU has been found to change the order
   by which the stores are made visible. When the tag is made visible
   before the other TLB values, other CPUs may use the invalid TLB values
   and do bad things.
   
   While here (i.e. not a fix) don't return errors from pmap_remove_vhpt()
   to callers of pmap_remove_pte(). Those callers don't check the return
   value and as such don't do what is needed to keep a consistent state.
   More importantly, pmap_remove_vhpt() can't really have an error without
   it indicating something unintended. Using KASSERT is therefore better.
   
   PR:		182999, 183227
 
 Modified:
   head/sys/ia64/ia64/pmap.c
 
 Modified: head/sys/ia64/ia64/pmap.c
 ==============================================================================
 --- head/sys/ia64/ia64/pmap.c	Mon Jan 20 18:15:06 2014	(r260913)
 +++ head/sys/ia64/ia64/pmap.c	Mon Jan 20 18:37:35 2014	(r260914)
 @@ -1303,6 +1303,8 @@ pmap_set_pte(struct ia64_lpte *pte, vm_o
  
  	pte->itir = PAGE_SHIFT << 2;
  
 +	ia64_mf();
 +
  	pte->tag = ia64_ttag(va);
  }
  
 @@ -1321,8 +1323,8 @@ pmap_remove_pte(pmap_t pmap, struct ia64
  	 * First remove from the VHPT.
  	 */
  	error = pmap_remove_vhpt(va);
 -	if (error)
 -		return (error);
 +	KASSERT(error == 0, ("%s: pmap_remove_vhpt returned %d",
 +	    __func__, error));
  
  	pmap_invalidate_page(va);
  
 _______________________________________________
 [email protected] mailing list
 http://lists.freebsd.org/mailman/listinfo/svn-src-all
 To unsubscribe, send any mail to "[email protected]"
 
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-ia64
To unsubscribe, send any mail to "[email protected]"