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From: Leon Romanovsky <leon@kernel.org>
To: Maxim Mikityanskiy <maximmi@nvidia.com>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>,
	Veaceslav Falico <vfalico@gmail.com>,
	Andy Gospodarek <andy@greyhouse.net>,
	Mahesh Bandewar <maheshb@google.com>,
	Nikolay Aleksandrov <nikolay@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Tariq Toukan <tariqt@nvidia.com>,
	netdev@vger.kernel.org
Subject: Re: [RFC PATCH net] bonding: Work around lockdep_is_held false positives
Date: Mon, 22 Mar 2021 16:09:41 +0200	[thread overview]
Message-ID: <YFilJZOraCqD0mVj@unreal> (raw)
In-Reply-To: <20210322123846.3024549-1-maximmi@nvidia.com>

On Mon, Mar 22, 2021 at 02:38:46PM +0200, Maxim Mikityanskiy wrote:
> After lockdep gets triggered for the first time, it gets disabled, and
> lockdep_enabled() will return false. It will affect lockdep_is_held(),
> which will start returning true all the time. Normally, it just disables
> checks that expect a lock to be held. However, the bonding code checks
> that a lock is NOT held, which triggers a false positive in WARN_ON.
> 
> This commit addresses the issue by replacing lockdep_is_held with
> spin_is_locked, which should have the same effect, but without suffering
> from disabling lockdep.
> 
> Fixes: ee6377147409 ("bonding: Simplify the xmit function for modes that use xmit_hash")
> Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
> Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
> ---
> While this patch works around the issue, I would like to discuss better
> options. Another straightforward approach is to extend lockdep API with
> lockdep_is_not_held(), which will be basically !lockdep_is_held() when
> lockdep is enabled, but will return true when !lockdep_enabled().

lockdep_assert_not_held() was added in this cycle to tip: locking/core
https://yhbt.net/lore/all/161475935945.20312.2870945278690244669.tip-bot2@tip-bot2/
https://yhbt.net/lore/all/878s779s9f.fsf@codeaurora.org/

Thanks

  reply	other threads:[~2021-03-22 14:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-22 12:38 [RFC PATCH net] bonding: Work around lockdep_is_held false positives Maxim Mikityanskiy
2021-03-22 14:09 ` Leon Romanovsky [this message]
2021-03-23 17:34   ` Maxim Mikityanskiy
2021-03-23 17:56     ` Jay Vosburgh
2021-03-23 19:02       ` Maxim Mikityanskiy

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