linux-kernel - Re: [PATCH 1/9] coresight: change coresight_device lock type to raw_spinlock

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:
 <GV1PR08MB10521520ABD7B72D92FD60DE9FB292@GV1PR08MB10521.eurprd08.prod.outlook.com>
Date: Thu, 28 Nov 2024 07:39:22 +0000
From: Yeo Reum Yun <YeoReum.Yun@....com>
To: Steven Rostedt <rostedt@...dmis.org>
CC: Suzuki Poulose <Suzuki.Poulose@....com>, "mike.leach@...aro.org"
	<mike.leach@...aro.org>, "james.clark@...aro.org" <james.clark@...aro.org>,
	"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
	"bigeasy@...utronix.de" <bigeasy@...utronix.de>, "clrkwllms@...nel.org"
	<clrkwllms@...nel.org>, "coresight@...ts.linaro.org"
	<coresight@...ts.linaro.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-rt-devel@...ts.linux.dev"
	<linux-rt-devel@...ts.linux.dev>, nd <nd@....com>
Subject: Re: [PATCH 1/9] coresight: change coresight_device lock type to
 raw_spinlock_t

Hi Steven,

> We should start documenting what is not real-time "safe". That is, if this
> code is executed, we have a loop here that holds a raw spin lock. This
> appears to make the time the raw spin lock held to be non deterministic.
> 
> If someone is running PREEMPT_RT and expects deterministic behavior, they
> cannot be using this code. That is fine, but we should probably create a
> document somewhere that notes this.
>
> -- Steve

I think it's quite deterministic becase the number of loop currently
determined by the number of preload_feats.

Also, I don't think the number of  feats will be loaded as much as
it can do undeterministic behavior since 
the number is not many and it is quite predictable.

Thanks.