From: Jakub Kicinski <kuba@kernel•org>
To: Saeed Mahameed <saeed@kernel•org>
Cc: Stanislav Fomichev <stfomichev@gmail•com>,
"David S. Miller" <davem@davemloft•net>,
Paolo Abeni <pabeni@redhat•com>,
Eric Dumazet <edumazet@google•com>,
Saeed Mahameed <saeedm@nvidia•com>,
netdev@vger•kernel.org, Tariq Toukan <tariqt@nvidia•com>,
Gal Pressman <gal@nvidia•com>,
Leon Romanovsky <leonro@nvidia•com>,
Dragos Tatulea <dtatulea@nvidia•com>
Subject: Re: [net-next 10/11] net/mlx5e: Implement queue mgmt ops and single channel swap
Date: Mon, 27 Jan 2025 11:27:44 -0800 [thread overview]
Message-ID: <20250127112744.0db2b45a@kernel.org> (raw)
In-Reply-To: <Z5PrXkL7taguM57W@x130>
On Fri, 24 Jan 2025 11:34:54 -0800 Saeed Mahameed wrote:
> On 24 Jan 07:26, Jakub Kicinski wrote:
> >> Are you expecting drivers to hold netdev_lock internally?
> >> I was thinking something more scalable, queue_mgmt API to take
> >> netdev_lock, and any other place in the stack that can access
> >> "netdev queue config" e.g ethtool/netlink/netdev_ops should grab
> >> netdev_lock as well, this is better for the future when we want to
> >> reduce rtnl usage in the stack to protect single netdev ops where
> >> netdev_lock will be sufficient, otherwise you will have to wait for ALL
> >> drivers to properly use netdev_lock internally to even start thinking of
> >> getting rid of rtnl from some parts of the core stack.
> >
> >Agreed, expecting drivers to get the locking right internally is easier
> >short term but messy long term. I'm thinking opt-in for drivers to have
> >netdev_lock taken by the core. Probably around all ops which today hold
> >rtnl_lock, to keep the expectations simple.
>
> Why opt-in? I don't see any overhead of taking netdev_lock by default in
> rtnl_lock flows.
We could, depends on how close we take the dev lock to the ndo vs to
rtnl_lock. Some drivers may call back into the stack so if we're not
careful enough we'll get flooded by static analysis reports saying
that we had deadlocked some old Sun driver :(
Then there are SW upper drivers like bonding which we'll need at
the very least lockdep nesting allocations for.
Would be great to solve all these issues, but IMHO not a hard
requirement, we can at least start with opt in. Unless always
taking the lock gives us some worthwhile invariant I haven't considered?
next prev parent reply other threads:[~2025-01-27 19:27 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-16 21:55 [pull request][net-next 00/11] mlx5 updates 2025-01-16 Saeed Mahameed
2025-01-16 21:55 ` [net-next 01/11] net: Kconfig NET_DEVMEM selects GENERIC_ALLOCATOR Saeed Mahameed
2025-01-16 21:55 ` [net-next 02/11] net/mlx5e: SHAMPO: Reorganize mlx5_rq_shampo_alloc Saeed Mahameed
2025-01-16 21:55 ` [net-next 03/11] net/mlx5e: SHAMPO: Remove redundant params Saeed Mahameed
2025-01-16 21:55 ` [net-next 04/11] net/mlx5e: SHAMPO: Improve hw gro capability checking Saeed Mahameed
2025-01-16 21:55 ` [net-next 05/11] net/mlx5e: SHAMPO: Separate pool for headers Saeed Mahameed
2025-01-16 21:55 ` [net-next 06/11] net/mlx5e: SHAMPO: Headers page pool stats Saeed Mahameed
2025-01-16 21:55 ` [net-next 07/11] net/mlx5e: Convert over to netmem Saeed Mahameed
2025-02-05 20:14 ` Mina Almasry
2025-04-09 12:40 ` Dragos Tatulea
2025-01-16 21:55 ` [net-next 08/11] net/mlx5e: Handle iov backed netmems Saeed Mahameed
2025-01-16 21:55 ` [net-next 09/11] net/mlx5e: Add support for UNREADABLE netmem page pools Saeed Mahameed
2025-01-16 21:55 ` [net-next 10/11] net/mlx5e: Implement queue mgmt ops and single channel swap Saeed Mahameed
2025-01-16 23:21 ` Jakub Kicinski
2025-01-16 23:46 ` Saeed Mahameed
2025-01-16 23:54 ` Jakub Kicinski
2025-01-24 0:39 ` Stanislav Fomichev
2025-01-24 0:55 ` Jakub Kicinski
2025-01-24 3:11 ` Saeed Mahameed
2025-01-24 15:26 ` Jakub Kicinski
2025-01-24 19:34 ` Saeed Mahameed
2025-01-27 19:27 ` Jakub Kicinski [this message]
2025-01-16 21:55 ` [net-next 11/11] net/mlx5e: Support ethtool tcp-data-split settings Saeed Mahameed
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