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Date: Fri, 29 Jun 2007 20:52:20 GMT
From: James Gritton <jamie@gritton.org>
To: freebsd-gnats-submit@FreeBSD.org
Subject: mbuf(9) has misleading comments on M_DONTWAIT and M_TRYWAIT
X-Send-Pr-Version: www-3.0

>Number:         114139
>Category:       docs
>Synopsis:       mbuf(9) has misleading comments on M_DONTWAIT and M_TRYWAIT
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jun 29 21:00:11 GMT 2007
>Closed-Date:    
>Last-Modified:  Tue Jan 22 16:10:02 UTC 2008
>Originator:     James Gritton
>Release:        Current (7)
>Organization:
>Environment:
FreeBSD celeborn.e.gritton.org 7.0-CURRENT FreeBSD 7.0-CURRENT #2: Fri Mar 16 23:11:05 MDT 2007     gritton@celeborn.e.gritton.org:/usr/src/sys/i386/compile/CELEBORN  i386

>Description:
The MGET section of mbuf(9) asserts that M_DONTWAIT shouldn't be confused with M_NOWAIT ("they are not the same").  In sys/mbuf.h, they are in fact the same, as M_DONTWAIT is merely defined as M_NOWAIT.

Also, M_TRYWAIT is said to wait for kern.ipc.mbuf_wait ticks, a tunable which apparently no longer exists (and really M_TRYWAIT is just M_WAITOK).
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:

From: Tom Rhodes <trhodes@FreeBSD.org>
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: docs/114139: mbuf(9) has misleading comments on M_DONTWAIT and
 M_TRYWAIT
Date: Tue, 22 Jan 2008 11:06:00 -0500

 Hi,
 
 I'm not completely sure on the first point, I think the missing
 context not copied from mbuf(9) does point out why they are
 different.  Compare mbuf.9 to sys/mbuf.h and double check.
 
 For the second point, I sent this patch to another developer for
 review:
 
 Index: mbuf.9
 ===================================================================
 RCS file: /home/ncvs/src/share/man/man9/mbuf.9,v
 retrieving revision 1.65
 diff -u -u -r1.65 mbuf.9
 --- mbuf.9	26 Feb 2007 15:17:19 -0000	1.65
 +++ mbuf.9	22 Jan 2008 11:52:59 -0000
 @@ -24,7 +24,7 @@
  .\"
  .\" $FreeBSD: src/share/man/man9/mbuf.9,v 1.65 2007/02/26 15:17:19 bms Exp $
  .\"
 -.Dd February 26, 2007
 +.Dd January 22, 2008
  .Dt MBUF 9
  .Os
  .\"
 @@ -363,12 +363,8 @@
  .Fa how
  is set to
  .Dv M_TRYWAIT ,
 -a failed allocation will result in the caller being put
 -to sleep for a designated
 -kern.ipc.mbuf_wait
 -.Xr ( sysctl 8
 -tunable)
 -number of ticks.
 +a failed allocation will result in the caller blocking until
 +resources are available and thus never return NULL.
  A number of other functions and macros related to
  .Vt mbufs
  have the same argument because they may
 
 Thanks,
 -- 
 Tom Rhodes
>Unformatted:
