From: Daniel Borkmann <daniel@iogearbox.net>
To: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Cc: ast@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org,
bjorn.topel@intel.com, magnus.karlsson@intel.com,
maximmi@mellanox.com
Subject: Re: [PATCH bpf 0/3] XSK related fixes
Date: Wed, 5 Feb 2020 22:21:47 +0100 [thread overview]
Message-ID: <20200205212147.GA5358@pc-9.home> (raw)
In-Reply-To: <20200205045834.56795-1-maciej.fijalkowski@intel.com>
On Wed, Feb 05, 2020 at 05:58:31AM +0100, Maciej Fijalkowski wrote:
> Cameron reported [0] that on fresh bpf-next he could not run multiple
> xdpsock instances in Tx-only mode on single network interface with i40e
> driver.
>
> Turns out that Maxim's series [1] which was adding RCU protection around
> ndo_xsk_wakeup added check against the __I40E_CONFIG_BUSY being set on
> pf->state within i40e_xsk_wakeup() - if it's set, return -ENETDOWN.
> Since this bit is set per PF when UMEM is being enabled/disabled, the
> situation Cameron stumbled upon was that when he launched second xdpsock
> instance, second UMEM was being registered, hence set __I40E_CONFIG_BUSY
> which is now observed by first xdpsock and therefore xdpsock's kick_tx()
> gets -ENETDOWN as errno.
>
> -ENETDOWN currently is not allowed in kick_tx(), so we were exiting the
> first application. Such exit means also XDP program being unloaded and
> its dedicated resources, which caused an -ENXIO being return in the
> second xdpsock instance.
>
> Let's fix the issue from both sides - protect ourselves from future
> xdpsock crashes by allowing for -ENETDOWN errno being set in kick_tx()
> (patch 3) and from driver side, return -EAGAIN for the case where PF is
> busy (patch 1).
>
> Remove also doubled variable from xdpsock_user.c (patch 2).
>
> Note that ixgbe seems not to be affected since UMEM registration sets
> the busy/disable bit per ring, not per PF.
>
> Thanks!
> Maciej
>
> [0]: https://www.spinics.net/lists/xdp-newbies/msg01558.html
> [1]: https://lore.kernel.org/netdev/20191217162023.16011-1-maximmi@mellanox.com/
Applied, thanks!
next prev parent reply other threads:[~2020-02-05 21:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-05 4:58 [PATCH bpf 0/3] XSK related fixes Maciej Fijalkowski
2020-02-05 4:58 ` [PATCH bpf 1/3] i40e: Relax i40e_xsk_wakeup's return value when PF is busy Maciej Fijalkowski
2020-02-05 4:58 ` [PATCH bpf 2/3] samples: bpf: drop doubled variable declaration in xdpsock Maciej Fijalkowski
2020-02-05 4:58 ` [PATCH bpf 3/3] samples: bpf: allow for -ENETDOWN " Maciej Fijalkowski
2020-02-05 21:21 ` Daniel Borkmann [this message]
2020-02-06 13:58 ` [PATCH bpf 0/3] XSK related fixes Maxim Mikityanskiy
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