在 2021/8/19 下午6:16, Maciej Fijalkowski 写道:

On Wed, Aug 18, 2021 at 04:30:15PM +0800, zhoufeng wrote:

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在 2021/8/17 下午7:10, Maciej Fijalkowski 写道:

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On Tue, Aug 17, 2021 at 03:54:07PM +0800, Feng zhou wrote:

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From: Feng Zhou <redacted>

The ixgbe driver currently generates a NULL pointer dereference with
some machine (online cpus < 63). This is due to the fact that the
maximum value of num_xdp_queues is nr_cpu_ids. Code is in
"ixgbe_set_rss_queues"".

That's a good catch, but we should fix set channels callback so that it
will not allow a setting of queues to be higher than the
num_online_cpus().

Please also include the tree in the patch subject that you're directing
the patch to.

Ok, Besides it, I will add more code in "ixgbe_set_channels":
/* verify the number of channels does not exceed num_online_cpus */
if (count > num_online_cpus())
	return -EINVAL;
If user want set queues num to be higher than the num_online_cpus(),
return error(-EINVAL).

What do you think?

Yes, in general you can refer to
drivers/net/ethernet/intel/ice/ice_ethtool.c and in particular:

/**
  * ice_get_max_rxq - return the maximum number of Rx queues for in a PF
  * @pf: PF structure
  */
static int ice_get_max_rxq(struct ice_pf *pf)
{
	return min3(pf->num_lan_msix, (u16)num_online_cpus(),
		    (u16)pf->hw.func_caps.common_cap.num_rxq);
}

Ok, refer to drivers/net/ethernet/intel/ice/ice_ethtool.c:
"ice_get_max_rxq"

I think, "ixgbe_max_channels":

return max_combined;

Instead of

return min_t(int, max_combined, num_online_cpus());

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I'd be also thankful if you Cc me on Intel XDP related patches.
Thanks!

Ok, of course.

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Here's how the problem repeats itself:
Some machine (online cpus < 63), And user set num_queues to 63 through
ethtool. Code is in the "ixgbe_set_channels",
adapter->ring_feature[RING_F_FDIR].limit = count;
It becames 63.
When user use xdp, "ixgbe_set_rss_queues" will set queues num.
adapter->num_rx_queues = rss_i;
adapter->num_tx_queues = rss_i;
adapter->num_xdp_queues = ixgbe_xdp_queues(adapter);
And rss_i's value is from
f = &adapter->ring_feature[RING_F_FDIR];
rss_i = f->indices = f->limit;
So "num_rx_queues" > "num_xdp_queues", when run to "ixgbe_xdp_setup",
for (i = 0; i < adapter->num_rx_queues; i++)
	if (adapter->xdp_ring[i]->xsk_umem)
lead to panic.
Call trace:
[exception RIP: ixgbe_xdp+368]
RIP: ffffffffc02a76a0  RSP: ffff9fe16202f8d0  RFLAGS: 00010297
RAX: 0000000000000000  RBX: 0000000000000020  RCX: 0000000000000000
RDX: 0000000000000000  RSI: 000000000000001c  RDI: ffffffffa94ead90
RBP: ffff92f8f24c0c18   R8: 0000000000000000   R9: 0000000000000000
R10: ffff9fe16202f830  R11: 0000000000000000  R12: ffff92f8f24c0000
R13: ffff9fe16202fc01  R14: 000000000000000a  R15: ffffffffc02a7530
ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
   7 [ffff9fe16202f8f0] dev_xdp_install at ffffffffa89fbbcc
   8 [ffff9fe16202f920] dev_change_xdp_fd at ffffffffa8a08808
   9 [ffff9fe16202f960] do_setlink at ffffffffa8a20235
10 [ffff9fe16202fa88] rtnl_setlink at ffffffffa8a20384
11 [ffff9fe16202fc78] rtnetlink_rcv_msg at ffffffffa8a1a8dd
12 [ffff9fe16202fcf0] netlink_rcv_skb at ffffffffa8a717eb
13 [ffff9fe16202fd40] netlink_unicast at ffffffffa8a70f88
14 [ffff9fe16202fd80] netlink_sendmsg at ffffffffa8a71319
15 [ffff9fe16202fdf0] sock_sendmsg at ffffffffa89df290
16 [ffff9fe16202fe08] __sys_sendto at ffffffffa89e19c8
17 [ffff9fe16202ff30] __x64_sys_sendto at ffffffffa89e1a64
18 [ffff9fe16202ff38] do_syscall_64 at ffffffffa84042b9
19 [ffff9fe16202ff50] entry_SYSCALL_64_after_hwframe at ffffffffa8c0008c

Fixes: 4a9b32f30f80 ("ixgbe: fix potential RX buffer starvation for
AF_XDP")
Signed-off-by: Feng Zhou <redacted>
---
   drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 8 ++++++--
   1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 14aea40da50f..5db496cc5070 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -10112,6 +10112,7 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
   	struct ixgbe_adapter *adapter = netdev_priv(dev);
   	struct bpf_prog *old_prog;
   	bool need_reset;
+	int num_queues;
   	if (adapter->flags & IXGBE_FLAG_SRIOV_ENABLED)
   		return -EINVAL;

@@ -10161,11 +10162,14 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
   	/* Kick start the NAPI context if there is an AF_XDP socket open
   	 * on that queue id. This so that receiving will start.
   	 */
-	if (need_reset && prog)
-		for (i = 0; i < adapter->num_rx_queues; i++)
+	if (need_reset && prog) {
+		num_queues = min_t(int, adapter->num_rx_queues,
+			adapter->num_xdp_queues);
+		for (i = 0; i < num_queues; i++)
   			if (adapter->xdp_ring[i]->xsk_pool)
   				(void)ixgbe_xsk_wakeup(adapter->netdev, i,
   						       XDP_WAKEUP_RX);
+	}
   	return 0;
   }

-- 
2.11.0