linux-kernel - Re: [PATCH net-next 0/8] netlink: align attributes when needed (patchset #3)

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Message-ID: <20160426115427.GB20950@soda.linbit>
Date:	Tue, 26 Apr 2016 13:54:27 +0200
From:	Lars Ellenberg <lars.ellenberg@...bit.com>
To:	Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, sd@...asysnail.net,
	johannes@...solutions.net, kvalo@...eaurora.org,
	linux-wireless@...r.kernel.org, jack@...e.com,
	linux-kernel@...r.kernel.org, pshelar@...ira.com,
	dev@...nvswitch.org, jhs@...atatu.com, philipp.reisner@...bit.com,
	drbd-dev@...ts.linbit.com
Subject: Re: [PATCH net-next 0/8] netlink: align attributes when needed
 (patchset #3)

On Tue, Apr 26, 2016 at 10:06:10AM +0200, Nicolas Dichtel wrote:
> 
> This is the continuation (series #3) of the work done to align netlink
> attributes when these attributes contain some 64-bit fields.
> 
> It's the last patchset from what I've seen.
> 
> The last user of nla_put_u64() is block/drbd. This module does not use
> standard netlink API (see all the stuff in include/linux/genl_magic_struct.h
> and include/linux/genl_magic_func.h). I didn't modify it because it's seems
> hard to do it whithout testing and fully understanding the context

Something like this should just work.

diff --git a/include/linux/genl_magic_struct.h b/include/linux/genl_magic_struct.h
index eecd19b..5715dac 100644
--- a/include/linux/genl_magic_struct.h
+++ b/include/linux/genl_magic_struct.h
@@ -80,7 +80,7 @@ extern void CONCAT_(GENL_MAGIC_FAMILY, _genl_unregister)(void);
 			nla_get_u32, nla_put_u32, true)
 #define __u64_field(attr_nr, attr_flag, name)	\
 	__field(attr_nr, attr_flag, name, NLA_U64, __u64, \
-			nla_get_u64, nla_put_u64, false)
+			nla_get_u64, nla_put_u64_64bit_unspec, false)
 #define __str_field(attr_nr, attr_flag, name, maxlen) \
 	__array(attr_nr, attr_flag, name, NLA_NUL_STRING, char, maxlen, \
 			nla_strlcpy, nla_put, false)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index e589cb3..38ba770 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -871,6 +871,18 @@ static inline int nla_put_u64_64bit(struct sk_buff *skb, int attrtype,
 }
 
 /**
+ * nla_put_u64_64bit_unspec - nla_put_u64_64bit() with padattr = 0
+ * @skb: socket buffer to add attribute to
+ * @attrtype: attribute type
+ * @value: numeric value
+ */
+static inline int nla_put_u64_64bit_unspec(struct sk_buff *skb, int attrtype,
+				    u64 value)
+{
+	return nla_put_64bit(skb, attrtype, sizeof(u64), &value, NLA_UNSPEC);
+}
+
+/**
  * nla_put_be64 - Add a __be64 netlink attribute to a socket buffer and align it
  * @skb: socket buffer to add attribute to
  * @attrtype: attribute type

> (for
> example, why include/linux/drbd_genl.h is not part of uapi?).
> Any thoughts?

probably should be.

Thanks,

    Lars