linux-kernel - Re: Question regarding mutex locking

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: <474CFA64.8050608@lwfinger.net>
Date:	Tue, 27 Nov 2007 23:19:32 -0600
From:	Larry Finger <larry.finger@...inger.net>
To:	Robert Hancock <hancockr@...w.ca>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Question regarding mutex locking

Robert Hancock wrote:
> Larry Finger wrote:
>> If a particular routine needs to lock a mutex, but it may be entered
>> with that mutex already locked,
>> would the following code be SMP safe?
>>
>> hold_lock = mutex_trylock()
>>
>> ..
>>
>> if (hold_lock)
>>     mutex_unlock()
> 
> Not if another task could be acquiring that lock at the same time, which
> is probably the case, otherwise you wouldn't need the mutex. In other
> words, if you're going to do this, you might as well toss the mutex
> entirely as it's about the same effect..
> 

Thanks for the help. Someday, I hope to understand this stuff.

Larry

-
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/