linux-kernel - Re: [PATCH] dmaengine: plx_dma: Fix potential deadlock on &plxdev->ring

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]

Date:   Thu, 27 Jul 2023 09:31:12 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Chengfeng Ye <dg573847474@...il.com>
Cc:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        vkoul@...nel.org, Yunbo Yu <yuyunbo519@...il.com>,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: plx_dma: Fix potential deadlock on
 &plxdev->ring_lock



On 7/27/23 00:48, Chengfeng Ye wrote:
> Hi Logan and Christophe,
> 
> Thanks much for the reply and reminder, and yes, spin_lock_bh() should
> be better.
> 
> When I wrote the patch I thought the spin_lock_bh() cannot be nested,
> and afraid that if some outside callers called .dma_tx_status() callback
> with softirq already disable, then spin_unlock_bh() would unintentionally
> re-enable softirq(). spin_lock_irqsave() is always safer in general thus I
> used it.
> 
> But I just check the document [1] about these API and found that _bh()
> can be nested. Then use spin_lock_bh() should be better due to
> performance concern.
> 
> 
>> So perhaps we should just revert 1d05a0bdb420?
> Then for this one I think revert 1d05a0bdb420 should be enough. May I
> ask to revert that patch, should I do anything further? (like sending
> a new patch).

Yes, I think you can just send a revert patch explaining the reasoning
further in a commit message.

Thanks,

Logan