taskstats: use the libnl API to align nlattr on 64-bit

Goal of this patch is to use the new libnl API to align netlink attribute
when needed.
The layout of the netlink message will be a bit different after the patch,
because the padattr (TASKSTATS_TYPE_STATS) will be inside the nested
attribute instead of before it.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 32 deletions

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 21f82c29c914..b3f05ee20d18 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -357,10 +357,6 @@ static int parse(struct nlattr *na, struct cpumask *mask)
         return ret;
 }
 
-#if defined(CONFIG_64BIT) && !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
-#define TASKSTATS_NEEDS_PADDING 1
-#endif
-
 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 {
         struct nlattr *na, *ret;
@@ -370,29 +366,6 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
                         ? TASKSTATS_TYPE_AGGR_PID
                         : TASKSTATS_TYPE_AGGR_TGID;
 
-        /*
-         * The taskstats structure is internally aligned on 8 byte
-         * boundaries but the layout of the aggregrate reply, with
-         * two NLA headers and the pid (each 4 bytes), actually
-         * force the entire structure to be unaligned. This causes
-         * the kernel to issue unaligned access warnings on some
-         * architectures like ia64. Unfortunately, some software out there
-         * doesn't properly unroll the NLA packet and assumes that the start
-         * of the taskstats structure will always be 20 bytes from the start
-         * of the netlink payload. Aligning the start of the taskstats
-         * structure breaks this software, which we don't want. So, for now
-         * the alignment only happens on architectures that require it
-         * and those users will have to update to fixed versions of those
-         * packages. Space is reserved in the packet only when needed.
-         * This ifdef should be removed in several years e.g. 2012 once
-         * we can be confident that fixed versions are installed on most
-         * systems. We add the padding before the aggregate since the
-         * aggregate is already a defined type.
-         */
-#ifdef TASKSTATS_NEEDS_PADDING
-        if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
-                goto err;
-#endif
         na = nla_nest_start(skb, aggr);
         if (!na)
                 goto err;
@@ -401,7 +374,8 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
                 nla_nest_cancel(skb, na);
                 goto err;
         }
-        ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
+        ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
+                                sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
         if (!ret) {
                 nla_nest_cancel(skb, na);
                 goto err;
@@ -500,10 +474,9 @@ static size_t taskstats_packet_size(void)
         size_t size;
 
         size = nla_total_size(sizeof(u32)) +
-                nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
-#ifdef TASKSTATS_NEEDS_PADDING
-        size += nla_total_size(0); /* Padding for alignment */
-#endif
+                nla_total_size_64bit(sizeof(struct taskstats)) +
+                nla_total_size(0);
+
         return size;
 }