Re: [PATCH 18/62] bnxt_en: Fix bnxt_dl_reload_up()

[Bart Van Assche <bart.vanassche@gmail.com>]

On 2/23/26 2:37 PM, Michael Chan wrote:
> On Mon, Feb 23, 2026 at 2:27 PM Bart Van Assche
> <bart.vanassche@gmail.com> wrote:
> 
>> My understanding is that bnxt_dl_reload_up() is only called if
>> bnxt_dl_reload_down() returns 0 (see also devlink_reload()).
>> bnxt_dl_reload_up() returns an error code (-EOPNOTSUPP) for other
>> actions than DEVLINK_RELOAD_ACTION_DRIVER_REINIT or
>> DEVLINK_RELOAD_ACTION_FW_ACTIVATE. Hence, bnxt_dl_reload_up() is only
>> called if "action" is either DEVLINK_RELOAD_ACTION_DRIVER_REINIT or
>> DEVLINK_RELOAD_ACTION_FW_ACTIVATE. In other words, the code in the
>> "default" clause will never be reached. So I think the above change is
>> correct but also that the patch description should be modified to
>> reflect that this is not a bug fix. Did I perhaps misunderstand
>> something?
>>
> Yes, your description is correct.  So perhaps a better cleanup would
> be to remove the default case in bnxt_dl_reload_up()?  Thanks.

Hmm ... wouldn't that trigger a -Wswitch warning, a warning that is
enabled by default for kernel code? From the gcc documentation:
"Warn whenever a switch statement has an index of enumerated type and
lacks a case for one or more of the named codes of that enumeration.
(The presence of a default label prevents this warning.) case labels
that do not correspond to enumerators also provoke warnings when this
option is used, unless the enumeration is marked with the flag_enum
attribute. This warning is enabled by -Wall."

Changing "default: return -EOPNOTSUPP;" into "default: BUG();" keeps
the Clang thread-sanitizer happy but does not comply with the kernel
coding style. Does the patch below look better?

Thanks,

Bart.

bnxt_en: Suppress thread-safety complaints about bnxt_dl_reload_up()

bnxt_dl_reload_down() returns an error code for actions that are not
supported. Hence, bnxt_dl_reload_up() won't be called for unsupported
actions. Since the compiler doesn't know this, add unlock calls to the
default clause. This patch suppresses a Clang thread-sanitizer
complaint. Compile-tested only.

Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Shantiprasad Shettar <shantiprasad.shettar@broadcom.com>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: netdev@vger.kernel.org
Fixes: 004b5008016a ("eth: bnxt: remove most dependencies on RTNL")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_devlink.c 
b/drivers/net/ethernet/broadcom/bnxt/bnxt_devlink.c
index 15de802bbac4..aa7ebd1426ed 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_devlink.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_devlink.c
@@ -562,6 +562,13 @@ static int bnxt_dl_reload_up(struct devlink *dl, 
enum devlink_reload_action acti
  		break;
  	}
  	default:
+		/*
+		 * Other actions have already been rejected by
+		 * bnxt_dl_reload_down().
+		 */
+		WARN_ON_ONCE(true);
+		netdev_unlock(bp->dev);
+		rtnl_unlock();
  		return -EOPNOTSUPP;
  	}