From: Michal Swiatkowski <michal.swiatkowski@linux•intel.com>
To: Jakub Kicinski <kuba@kernel•org>
Cc: davem@davemloft•net, netdev@vger•kernel.org, edumazet@google•com,
pabeni@redhat•com, andrew+netdev@lunn•ch, horms@kernel•org,
jdamato@fastly•com, almasrymina@google•com
Subject: Re: [PATCH net-next] net: warn during dump if NAPI list is not sorted
Date: Fri, 10 Jan 2025 07:16:50 +0100 [thread overview]
Message-ID: <Z4C7Un9FoSGZ5q98@mev-dev.igk.intel.com> (raw)
In-Reply-To: <20250110004505.3210140-1-kuba@kernel.org>
On Thu, Jan 09, 2025 at 04:45:04PM -0800, Jakub Kicinski wrote:
> Dump continuation depends on the NAPI list being sorted.
> Broken netlink dump continuation may be rare and hard to debug
> so add a warning if we notice the potential problem while walking
> the list.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel•org>
> ---
> This is really a follow up to commit d6c7b03497ee ("net: make sure
> we retain NAPI ordering on netdev->napi_list") but I had to wait
> for some fixes to make it to net-next.
>
> CC: jdamato@fastly•com
> CC: almasrymina@google•com
> ---
> net/core/netdev-genl.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> index a3bdaf075b6b..c59619a2ec23 100644
> --- a/net/core/netdev-genl.c
> +++ b/net/core/netdev-genl.c
> @@ -263,14 +263,21 @@ netdev_nl_napi_dump_one(struct net_device *netdev, struct sk_buff *rsp,
> struct netdev_nl_dump_ctx *ctx)
> {
> struct napi_struct *napi;
> + unsigned int prev_id;
> int err = 0;
>
> if (!(netdev->flags & IFF_UP))
> return err;
>
> + prev_id = UINT_MAX;
> list_for_each_entry(napi, &netdev->napi_list, dev_list) {
> if (napi->napi_id < MIN_NAPI_ID)
> continue;
> +
> + /* Dump continuation below depends on the list being sorted */
> + WARN_ON_ONCE(napi->napi_id >= prev_id);
> + prev_id = napi->napi_id;
> +
> if (ctx->napi_id && napi->napi_id >= ctx->napi_id)
> continue;
>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux•intel.com>
> --
> 2.47.1
next prev parent reply other threads:[~2025-01-10 6:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-10 0:45 [PATCH net-next] net: warn during dump if NAPI list is not sorted Jakub Kicinski
2025-01-10 6:16 ` Michal Swiatkowski [this message]
2025-01-10 18:06 ` Joe Damato
2025-01-11 2:50 ` patchwork-bot+netdevbpf
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