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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, Calvin Owens <calvinowens@fb.com>,
        Michael Chan <michael.chan@broadcom.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 108/146] bnxt_en: Fix sources of spurious netpoll warnings
Date: Mon,  1 Jan 2018 15:38:19 +0100
Message-Id: <20180101140139.632147656@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Calvin Owens <calvinowens@fb.com>


[ Upstream commit 2edbdb3159d6f6bd3a9b6e7f789f2b879699a519 ]

After applying 2270bc5da3497945 ("bnxt_en: Fix netpoll handling") and
903649e718f80da2 ("bnxt_en: Improve -ENOMEM logic in NAPI poll loop."),
we still see the following WARN fire:

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 1875170 at net/core/netpoll.c:165 netpoll_poll_dev+0x15a/0x160
  bnxt_poll+0x0/0xd0 exceeded budget in poll
  <snip>
  Call Trace:
   [<ffffffff814be5cd>] dump_stack+0x4d/0x70
   [<ffffffff8107e013>] __warn+0xd3/0xf0
   [<ffffffff8107e07f>] warn_slowpath_fmt+0x4f/0x60
   [<ffffffff8179519a>] netpoll_poll_dev+0x15a/0x160
   [<ffffffff81795f38>] netpoll_send_skb_on_dev+0x168/0x250
   [<ffffffff817962fc>] netpoll_send_udp+0x2dc/0x440
   [<ffffffff815fa9be>] write_ext_msg+0x20e/0x250
   [<ffffffff810c8125>] call_console_drivers.constprop.23+0xa5/0x110
   [<ffffffff810c9549>] console_unlock+0x339/0x5b0
   [<ffffffff810c9a88>] vprintk_emit+0x2c8/0x450
   [<ffffffff810c9d5f>] vprintk_default+0x1f/0x30
   [<ffffffff81173df5>] printk+0x48/0x50
   [<ffffffffa0197713>] edac_raw_mc_handle_error+0x563/0x5c0 [edac_core]
   [<ffffffffa0197b9b>] edac_mc_handle_error+0x42b/0x6e0 [edac_core]
   [<ffffffffa01c3a60>] sbridge_mce_output_error+0x410/0x10d0 [sb_edac]
   [<ffffffffa01c47cc>] sbridge_check_error+0xac/0x130 [sb_edac]
   [<ffffffffa0197f3c>] edac_mc_workq_function+0x3c/0x90 [edac_core]
   [<ffffffff81095f8b>] process_one_work+0x19b/0x480
   [<ffffffff810967ca>] worker_thread+0x6a/0x520
   [<ffffffff8109c7c4>] kthread+0xe4/0x100
   [<ffffffff81884c52>] ret_from_fork+0x22/0x40

This happens because we increment rx_pkts on -ENOMEM and -EIO, resulting
in rx_pkts > 0. Fix this by only bumping rx_pkts if we were actually
given a non-zero budget.

Signed-off-by: Calvin Owens <calvinowens@fb.com>
Acked-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 |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1875,7 +1875,7 @@ static int bnxt_poll_work(struct bnxt *b
 			 * here forever if we consistently cannot allocate
 			 * buffers.
 			 */
-			else if (rc == -ENOMEM)
+			else if (rc == -ENOMEM && budget)
 				rx_pkts++;
 			else if (rc == -EBUSY)	/* partial completion */
 				break;
@@ -1961,7 +1961,7 @@ static int bnxt_poll_nitroa0(struct napi
 				cpu_to_le32(RX_CMPL_ERRORS_CRC_ERROR);
 
 			rc = bnxt_rx_pkt(bp, bnapi, &raw_cons, &event);
-			if (likely(rc == -EIO))
+			if (likely(rc == -EIO) && budget)
 				rx_pkts++;
 			else if (rc == -EBUSY)	/* partial completion */
 				break;