Linux RDMA and InfiniBand development
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-rdma@vger.kernel.org, netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
	Andrew Lunn <andrew+netdev@lunn.ch>,
	Eric Dumazet <edumazet@google.com>,
	Ilias Apalodimas <ilias.apalodimas@linaro.org>,
	Jakub Kicinski <kuba@kernel.org>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	Leon Romanovsky <leon@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Saeed Mahameed <saeedm@nvidia.com>,
	Simon Horman <horms@kernel.org>, Tariq Toukan <tariqt@nvidia.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Yunsheng Lin <linyunsheng@huawei.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH net-next 0/2] page_pool: Convert stats to u64_stats_t.
Date: Fri, 21 Feb 2025 12:52:19 +0100	[thread overview]
Message-ID: <20250221115221.291006-1-bigeasy@linutronix.de> (raw)

This is a follow-up on
	https://lore.kernel.org/all/20250213093925.x_ggH1aj@linutronix.de/

to convert the page_pool statistics to u64_stats_t to avoid u64 related
problems on 32bit architectures.
While looking over it, the comment for recycle_stat_inc() says that it
is safe to use in preemptible context. The 32bit update is split into
two 32bit writes and if we get preempted in the middle and another one
makes an update then the value gets inconsistent and the previous update
can overwrite the following. (Rare but still).
I don't know if it is ensured that only *one* update can happen because
the stats are per-CPU and per NAPI device. But there will be now a
warning on 32bit if this is really attempted in preemptible context.

Sebastian Andrzej Siewior (2):
  page_pool: Convert page_pool_recycle_stats to u64_stats_t.
  page_pool: Convert page_pool_alloc_stats to u64_stats_t.

 Documentation/networking/page_pool.rst        |  4 +-
 .../ethernet/mellanox/mlx5/core/en_stats.c    | 24 ++---
 include/linux/u64_stats_sync.h                |  5 +
 include/net/page_pool/types.h                 | 27 +++---
 net/core/page_pool.c                          | 95 +++++++++++++------
 net/core/page_pool_user.c                     | 22 ++---
 6 files changed, 113 insertions(+), 64 deletions(-)

-- 
2.47.2


             reply	other threads:[~2025-02-21 11:52 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-21 11:52 Sebastian Andrzej Siewior [this message]
2025-02-21 11:52 ` [PATCH net-next 1/2] page_pool: Convert page_pool_recycle_stats to u64_stats_t Sebastian Andrzej Siewior
2025-02-21 17:21   ` Joe Damato
2025-02-26 12:06     ` Sebastian Andrzej Siewior
2025-02-22  8:13   ` Yunsheng Lin
2025-02-25 11:27     ` Paolo Abeni
2025-02-26  9:28     ` Sebastian Andrzej Siewior
2025-02-21 11:52 ` [PATCH net-next 2/2] page_pool: Convert page_pool_alloc_stats " Sebastian Andrzej Siewior
2025-02-21 17:30   ` Joe Damato
2025-02-22  8:13   ` Yunsheng Lin
2025-02-21 17:10 ` [PATCH net-next 0/2] page_pool: Convert stats " Joe Damato
2025-02-26 10:27   ` Sebastian Andrzej Siewior

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