linux-kernel - Re: [PATCH 1/5] Use mutex instead of semaphore in the Host AP driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LFD.0.999.0707300842350.10861@enigma.security.iitk.ac.in>
Date:	Mon, 30 Jul 2007 08:48:57 +0530 (IST)
From:	Satyam Sharma <satyam@...radead.org>
To:	Michael Buesch <mb@...sch.de>
cc:	Matthias Kaehlcke <matthias.kaehlcke@...il.com>,
	linville@...driver.com, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [PATCH 1/5] Use mutex instead of semaphore in the Host AP
 driver



On Mon, 30 Jul 2007, Michael Buesch wrote:

> On Sunday 29 July 2007 23:34, Matthias Kaehlcke wrote:
> > The Host AP driver uses a semaphore as mutex. Use the mutex API
> > instead of the (binary) semaphore.
> > 
> > Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@...il.com>

[ Something seems to have gone wrong with your diff / patch / script.
  There was no diff header here, which should have been. ]

> > -	res = down_interruptible(&local->rid_bap_sem);
> > +	res = mutex_lock_interruptible(&local->rid_bap_mtx);
> >  	if (res)
> >  		return res;
> >  
> > @@ -902,7 +902,7 @@ static int hfa384x_set_rid(struct net_device *dev, u16 rid, void *buf, int len)
> >  	/* RID len in words and +1 for rec.rid */
> >  	rec.len = cpu_to_le16(len / 2 + len % 2 + 1);
> >  
> > -	res = down_interruptible(&local->rid_bap_sem);
> > +	res = mutex_lock_interruptible(&local->rid_bap_mtx);
> >  	if (res)
> >  		return res;
> >  
> 
> Is res returned to userspace? If yes, that's not right.

Yup, that's not right.

> On a interrupted mutex allocation you should return
> -ERESTARTSYS to userspace.

Nope, userspace must not see ERESTARTSYS (I /think/ this is the third
time I'm participating in this exact same discussion :-)

If the return would be caught by a previous in-kernel caller in the
call chain, ERESTARTSYS is okay and it could try to restart the
operation. However, if the return goes unfiltered directly to
userspace, EINTR is the correct choice.


Satyam
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/