diff mbox series

[next,S92,5/9] i40e: use WARN_ONCE to replace the commented BUG_ON size check

Message ID 20180517080840.30192-5-alice.michael@intel.com
State Accepted
Delegated to: Jeff Kirsher
Headers show
Series [next,S92,1/9] i40e: free skb after clearing lock in ptp_stop | expand

Commit Message

Michael, Alice May 17, 2018, 8:08 a.m. UTC 
From: Jacob Keller <jacob.e.keller@intel.com>

We don't really want to use BUG_ON here since that would completely
crash the kernel, thus the reason we commented it out. We *can't* use
BUILD_BUG_ON because at least now (a) the sizes aren't constant (we are
fixing this) and (b) not all compilers are smart enough to understand
that "p - data" is a constant.

Instead, just use a WARN_ONCE so that the first time we end up with an
incorrect size we will dump a stack trace and a message, hopefully
highlighting the issues early in testing.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_ethtool.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Bowers, AndrewX May 17, 2018, 10:13 p.m. UTC | #1 
> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On
> Behalf Of Alice Michael
> Sent: Thursday, May 17, 2018 1:09 AM
> To: Michael, Alice <alice.michael@intel.com>; intel-wired-
> lan@lists.osuosl.org
> Subject: [Intel-wired-lan] [next PATCH S92 5/9] i40e: use WARN_ONCE to
> replace the commented BUG_ON size check
> 
> From: Jacob Keller <jacob.e.keller@intel.com>
> 
> We don't really want to use BUG_ON here since that would completely crash
> the kernel, thus the reason we commented it out. We *can't* use
> BUILD_BUG_ON because at least now (a) the sizes aren't constant (we are
> fixing this) and (b) not all compilers are smart enough to understand that "p -
> data" is a constant.
> 
> Instead, just use a WARN_ONCE so that the first time we end up with an
> incorrect size we will dump a stack trace and a message, hopefully
> highlighting the issues early in testing.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_ethtool.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
diff mbox series

Patch

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
index cc09dd7..9bddae4 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
@@ -1672,8 +1672,8 @@  static void i40e_get_stat_strings(struct net_device *netdev, u8 *data)
 	struct i40e_netdev_priv *np = netdev_priv(netdev);
 	struct i40e_vsi *vsi = np->vsi;
 	struct i40e_pf *pf = vsi->back;
-	char *p = (char *)data;
 	unsigned int i;
+	u8 *p = data;
 
 	for (i = 0; i < I40E_NETDEV_STATS_LEN; i++) {
 		snprintf(p, ETH_GSTRING_LEN, "%s",
@@ -1744,7 +1744,9 @@  static void i40e_get_stat_strings(struct net_device *netdev, u8 *data)
 			 "port.rx_priority_%u_xon_2_xoff", i);
 		p += ETH_GSTRING_LEN;
 	}
-	/* BUG_ON(p - data != I40E_STATS_LEN * ETH_GSTRING_LEN); */
+
+	WARN_ONCE(p - data != i40e_get_stats_count(netdev) * ETH_GSTRING_LEN,
+		  "stat strings count mismatch!");
 }
 
 static void i40e_get_priv_flag_strings(struct net_device *netdev, u8 *data)