linux-kernel - Re: [EXTERNAL] Re: [PATCH net v2 1/4] octeon_ep: fix race conditions in ndo_get

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Message-ID: <CANn89iJ-vz8dfrHv2QChiQWUk14bQJfykTTYLMmOuHejgii4nA@mail.gmail.com>
Date: Wed, 18 Dec 2024 16:39:41 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Shinas Rasheed <srasheed@...vell.com>
Cc: Larysa Zaremba <larysa.zaremba@...el.com>, 
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Haseeb Gani <hgani@...vell.com>, 
	Sathesh B Edara <sedara@...vell.com>, Vimlesh Kumar <vimleshk@...vell.com>, 
	"thaller@...hat.com" <thaller@...hat.com>, "wizhao@...hat.com" <wizhao@...hat.com>, 
	"kheib@...hat.com" <kheib@...hat.com>, "konguyen@...hat.com" <konguyen@...hat.com>, 
	"horms@...nel.org" <horms@...nel.org>, "einstein.xue@...axg.com" <einstein.xue@...axg.com>, 
	Veerasenareddy Burru <vburru@...vell.com>, Andrew Lunn <andrew+netdev@...n.ch>, 
	"David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Abhijit Ayarekar <aayarekar@...vell.com>, Satananda Burla <sburla@...vell.com>
Subject: Re: [EXTERNAL] Re: [PATCH net v2 1/4] octeon_ep: fix race conditions
 in ndo_get_stats64

On Wed, Dec 18, 2024 at 4:25 PM Shinas Rasheed <srasheed@...vell.com> wrote:

> Hi Eric,
>
> This patch is not a workaround. In some setups, we were seeing races with regards
> to resource freeing between ndo_stop() and ndo_get_stats(). Hence to sync with the view of
> resources, a synchronize_net() is called in ndo_stop(). Please let me know if you see anything wrong here.

We do not add a synchronize_net() without a very strong explanation
(details, not a weak sentence in the changelog).

Where is the opposite barrier in your patch ?

I am saying you do not need this, unless you can show evidence.

If your ndo_get_stats() needs to call netif_running(), this would be
the fix IMO.