netdev - [PATCH net 1/3] bnxt_en: Fix possible bnxt_open() failure caused by wrong RFS flag

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Message-Id: <1651540392-2260-2-git-send-email-michael.chan@broadcom.com>
Date:   Mon,  2 May 2022 21:13:10 -0400
From:   Michael Chan <michael.chan@...adcom.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, kuba@...nel.org, gospo@...adcom.com,
        Somnath Kotur <somnath.kotur@...adcom.com>
Subject: [PATCH net 1/3] bnxt_en: Fix possible bnxt_open() failure caused by wrong RFS flag

From: Somnath Kotur <somnath.kotur@...adcom.com>

bnxt_open() can fail in this code path, especially on a VF when
it fails to reserve default rings:

bnxt_open()
  __bnxt_open_nic()
    bnxt_clear_int_mode()
    bnxt_init_dflt_ring_mode()

RX rings would be set to 0 when we hit this error path.

It is possible for a subsequent bnxt_open() call to potentially succeed
with a code path like this:

bnxt_open()
  bnxt_hwrm_if_change()
    bnxt_fw_init_one()
      bnxt_fw_init_one_p3()
        bnxt_set_dflt_rfs()
          bnxt_rfs_capable()
            bnxt_hwrm_reserve_rings()

On older chips, RFS is capable if we can reserve the number of vnics that
is equal to RX rings + 1.  But since RX rings is still set to 0 in this
code path, we may mistakenly think that RFS is supported for 0 RX rings.

Later, when the default RX rings are reserved and we try to enable
RFS, it would fail and cause bnxt_open() to fail unnecessarily.

We fix this in 2 places.  bnxt_rfs_capable() will always return false if
RX rings is not yet set.  bnxt_init_dflt_ring_mode() will call
bnxt_set_dflt_rfs() which will always clear the RFS flags if RFS is not
supported.

Fixes: 20d7d1c5c9b1 ("bnxt_en: reliably allocate IRQ table on reset to avoid crash")
Signed-off-by: Somnath Kotur <somnath.kotur@...adcom.com>
Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 874fad0a5cf8..2818cfef42f8 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -10983,7 +10983,7 @@ static bool bnxt_rfs_capable(struct bnxt *bp)
 
 	if (bp->flags & BNXT_FLAG_CHIP_P5)
 		return bnxt_rfs_supported(bp);
-	if (!(bp->flags & BNXT_FLAG_MSIX_CAP) || !bnxt_can_reserve_rings(bp))
+	if (!(bp->flags & BNXT_FLAG_MSIX_CAP) || !bnxt_can_reserve_rings(bp) || !bp->rx_nr_rings)
 		return false;
 
 	vnics = 1 + bp->rx_nr_rings;
@@ -13234,10 +13234,9 @@ static int bnxt_init_dflt_ring_mode(struct bnxt *bp)
 		goto init_dflt_ring_err;
 
 	bp->tx_nr_rings_per_tc = bp->tx_nr_rings;
-	if (bnxt_rfs_supported(bp) && bnxt_rfs_capable(bp)) {
-		bp->flags |= BNXT_FLAG_RFS;
-		bp->dev->features |= NETIF_F_NTUPLE;
-	}
+
+	bnxt_set_dflt_rfs(bp);
+
 init_dflt_ring_err:
 	bnxt_ulp_irq_restart(bp, rc);
 	return rc;
-- 
2.18.1


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