From: Vinicius Costa Gomes <vinicius.gomes@intel.com> To: Jeff Evanson <jeff.evanson@gmail.com>, Jesse Brandeburg <jesse.brandeburg@intel.com>, Tony Nguyen <anthony.l.nguyen@intel.com>, "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Jesper Dangaard Brouer <hawk@kernel.org>, John Fastabend <john.fastabend@gmail.com>, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Cc: jeff.evanson@qsc.com, jeff.evanson@gmail.com Subject: Re: [PATCH 1/2] Fix race in igc_xdp_xmit_zc Date: Mon, 18 Apr 2022 13:39:48 -0400 [thread overview] Message-ID: <871qxu5lzv.fsf@intel.com> (raw) In-Reply-To: <20220415210421.11217-1-jeff.evanson@qsc.com> Hi Jeff, Jeff Evanson <jeff.evanson@gmail.com> writes: > in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock > to prevent racing with other users of the tx ring Some style things to change: - Some more details on what is the effect of the race condition, and perhaps the conditions to reproduce it (what I could imagine is that you would need two applications (one using AF_XDP and another one using AF_PACKET, for example) sending packets to the same queue. - I think this patch is solving a real problem, so directing this patch to the net-queue (using 'PATCH net-queue' as subject prefix) would make sense. - Please add the 'Fixes:' tag so this commit can be applied to any stable tree that makes sense. Apart from those style changes, the code looks good. Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> > > Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com> > --- > drivers/net/ethernet/intel/igc/igc_main.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c > index 1c00ee310c19..a36a18c84aeb 100644 > --- a/drivers/net/ethernet/intel/igc/igc_main.c > +++ b/drivers/net/ethernet/intel/igc/igc_main.c > @@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) > struct netdev_queue *nq = txring_txq(ring); > union igc_adv_tx_desc *tx_desc = NULL; > int cpu = smp_processor_id(); > - u16 ntu = ring->next_to_use; > + u16 ntu; > struct xdp_desc xdp_desc; > u16 budget; > > @@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) > > __netif_tx_lock(nq, cpu); > > + ntu = ring->next_to_use; > + > budget = igc_desc_unused(ring); > > while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) { > -- > 2.17.1 > -- Vinicius
WARNING: multiple messages have this Message-ID (diff)
From: Vinicius Costa Gomes <vinicius.gomes@intel.com> To: intel-wired-lan@osuosl.org Subject: [Intel-wired-lan] [PATCH 1/2] Fix race in igc_xdp_xmit_zc Date: Mon, 18 Apr 2022 13:39:48 -0400 [thread overview] Message-ID: <871qxu5lzv.fsf@intel.com> (raw) In-Reply-To: <20220415210421.11217-1-jeff.evanson@qsc.com> Hi Jeff, Jeff Evanson <jeff.evanson@gmail.com> writes: > in igc_xdp_xmit_zc, initialize next_to_use while holding the netif_tx_lock > to prevent racing with other users of the tx ring Some style things to change: - Some more details on what is the effect of the race condition, and perhaps the conditions to reproduce it (what I could imagine is that you would need two applications (one using AF_XDP and another one using AF_PACKET, for example) sending packets to the same queue. - I think this patch is solving a real problem, so directing this patch to the net-queue (using 'PATCH net-queue' as subject prefix) would make sense. - Please add the 'Fixes:' tag so this commit can be applied to any stable tree that makes sense. Apart from those style changes, the code looks good. Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> > > Signed-off-by: Jeff Evanson <jeff.evanson@qsc.com> > --- > drivers/net/ethernet/intel/igc/igc_main.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c > index 1c00ee310c19..a36a18c84aeb 100644 > --- a/drivers/net/ethernet/intel/igc/igc_main.c > +++ b/drivers/net/ethernet/intel/igc/igc_main.c > @@ -2598,7 +2598,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) > struct netdev_queue *nq = txring_txq(ring); > union igc_adv_tx_desc *tx_desc = NULL; > int cpu = smp_processor_id(); > - u16 ntu = ring->next_to_use; > + u16 ntu; > struct xdp_desc xdp_desc; > u16 budget; > > @@ -2607,6 +2607,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) > > __netif_tx_lock(nq, cpu); > > + ntu = ring->next_to_use; > + > budget = igc_desc_unused(ring); > > while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) { > -- > 2.17.1 > -- Vinicius
next prev parent reply other threads:[~2022-04-18 17:40 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-15 21:04 [PATCH 1/2] Fix race in igc_xdp_xmit_zc Jeff Evanson 2022-04-15 21:04 ` [Intel-wired-lan] " Jeff Evanson 2022-04-18 17:39 ` Vinicius Costa Gomes [this message] 2022-04-18 17:39 ` Vinicius Costa Gomes 2022-04-20 10:37 ` Alexander Lobakin 2022-04-20 10:37 ` Alexander Lobakin
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