netdev - Re: [PATCH net-next] bnxt_en: replace PTP spinlock with seqlock

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: <20241014163538.1ac0d88d@kernel.org>
Date: Mon, 14 Oct 2024 16:35:38 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Vadim Fedorenko <vadfed@...a.com>
Cc: Michael Chan <michael.chan@...adcom.com>, Vadim Fedorenko
 <vadim.fedorenko@...ux.dev>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] bnxt_en: replace PTP spinlock with seqlock

On Mon, 14 Oct 2024 16:29:47 -0700 Vadim Fedorenko wrote:
> -	spin_lock_bh(&ptp->ptp_lock);
> +	write_seqlock_irqsave(&ptp->ptp_lock, flags);
>  	timecounter_adjtime(&ptp->tc, delta);
> -	spin_unlock_bh(&ptp->ptp_lock);
> +	write_sequnlock_irqrestore(&ptp->ptp_lock, flags);

I think when you adjtime / adjfine (IOW on all the write path) you still
need the spin lock. But in addition also the seq lock. And then the
read path can take just the seq lock.

This will also remove any uncertainty about the bit ops.