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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Rob Sherwood <rsher@fb.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Michael Chan <michael.chan@broadcom.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 67/71] bnxt: dont enable NAPI until rings are ready
Date:   Fri, 11 Sep 2020 14:46:51 +0200
Message-Id: <20200911122508.289139691@linuxfoundation.org>
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From: Jakub Kicinski <kuba@kernel.org>

commit 96ecdcc992eb7f468b2cf829b0f5408a1fad4668 upstream.

Netpoll can try to poll napi as soon as napi_enable() is called.
It crashes trying to access a doorbell which is still NULL:

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 CPU: 59 PID: 6039 Comm: ethtool Kdump: loaded Tainted: G S                5.9.0-rc1-00469-g5fd99b5d9950-dirty #26
 RIP: 0010:bnxt_poll+0x121/0x1c0
 Code: c4 20 44 89 e0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 41 8b 86 a0 01 00 00 41 23 85 18 01 00 00 49 8b 96 a8 01 00 00 0d 00 00 00 24 <89> 02
41 f6 45 77 02 74 cb 49 8b ae d8 01 00 00 31 c0 c7 44 24 1a
  netpoll_poll_dev+0xbd/0x1a0
  __netpoll_send_skb+0x1b2/0x210
  netpoll_send_udp+0x2c9/0x406
  write_ext_msg+0x1d7/0x1f0
  console_unlock+0x23c/0x520
  vprintk_emit+0xe0/0x1d0
  printk+0x58/0x6f
  x86_vector_activate.cold+0xf/0x46
  __irq_domain_activate_irq+0x50/0x80
  __irq_domain_activate_irq+0x32/0x80
  __irq_domain_activate_irq+0x32/0x80
  irq_domain_activate_irq+0x25/0x40
  __setup_irq+0x2d2/0x700
  request_threaded_irq+0xfb/0x160
  __bnxt_open_nic+0x3b1/0x750
  bnxt_open_nic+0x19/0x30
  ethtool_set_channels+0x1ac/0x220
  dev_ethtool+0x11ba/0x2240
  dev_ioctl+0x1cf/0x390
  sock_do_ioctl+0x95/0x130

Reported-by: Rob Sherwood <rsher@fb.com>
Fixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -5589,14 +5589,14 @@ static int __bnxt_open_nic(struct bnxt *
 		}
 	}
 
-	bnxt_enable_napi(bp);
-
 	rc = bnxt_init_nic(bp, irq_re_init);
 	if (rc) {
 		netdev_err(bp->dev, "bnxt_init_nic err: %x\n", rc);
-		goto open_err;
+		goto open_err_irq;
 	}
 
+	bnxt_enable_napi(bp);
+
 	if (link_re_init) {
 		mutex_lock(&bp->link_lock);
 		rc = bnxt_update_phy_setting(bp);
@@ -5618,9 +5618,6 @@ static int __bnxt_open_nic(struct bnxt *
 
 	return 0;
 
-open_err:
-	bnxt_disable_napi(bp);
-
 open_err_irq:
 	bnxt_del_napi(bp);