Subject: Re: kern/36673 (dubious code is sysmon_envsys)
To: None <xtraeme@NetBSD.org, gnats-admin@netbsd.org,>
From: YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
List: netbsd-bugs
Date: 07/25/2007 11:45:05
The following reply was made to PR kern/36673; it has been noted by GNATS.

From: yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi)
To: gnats-bugs@NetBSD.org
Cc: xtraeme@NetBSD.org, gnats-admin@netbsd.org,
	netbsd-bugs@netbsd.org
Subject: Re: kern/36673 (dubious code is sysmon_envsys)
Date: Wed, 25 Jul 2007 20:44:52 +0900 (JST)

 > The following reply was made to PR kern/36673; it has been noted by GNATS.
 > 
 > From: Juan RP <juan@xtrarom.org>
 > To: yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi)
 > Cc: gnats-bugs@NetBSD.org
 > Subject: Re: kern/36673 (dubious code is sysmon_envsys)
 > Date: Wed, 25 Jul 2007 12:58:12 +0200
 > 
 >  On Wed, 25 Jul 2007 09:15:38 +0900 (JST)
 >  yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi) wrote:
 >  
 >  > > On Mon, 23 Jul 2007 23:20:03 +0000 (UTC)
 >  > > yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi) wrote:
 >  > > 
 >  > > >  the usages of these mutexes are not obvious or documented.
 >  > > >  
 >  > > >  for example,
 >  > > >  - i can't understand why sysmon_envsys_createplist acquires
 >  > > >   sme_mtx in the loop.
 >  > > 
 >  > > I wanted to protect the sme_gtredata function callback, this one
 >  > > is executed in the driver to refresh data in the sensors.
 >  > 
 >  > protect from what?
 >  
 >  Protect from retrieve sensor data from multiple threads.
 
 is it visible from other threads at this point?
 
 >  > > One thing that is not clear to me is if I can allocate/deallocate
 >  > > memory with a mutex held, can you please answer?
 >  > 
 >  > as i already answered, it depends.
 >  > don't do it if you are not sure.
 >  
 >  I'm not doing it on my code, but I would like to have more details than
 >  "it depends". Depends of what? depends if is it a spin mutex or an
 >  adaptive mutex?
 
 it's unsafe if it can interfere pagedaemon, for example.
 
 YAMAMOTO Takashi