On Sat, Jan 30, 2016 at 03:39:01PM -0500, Jarod Wilson wrote:
> On Sat, Jan 30, 2016 at 10:34:32AM -0800, Eric Dumazet wrote:
> > On Sat, 2016-01-30 at 13:19 -0500, Jarod Wilson wrote:
> > > The netdev_stats_to_stats64 function copies the deprecated
> > > net_device_stats format stats into rtnl_link_stats64 for legacy support
> > > purposes, but with the BUILD_BUG_ON as it was, it wasn't possible to
> > > extend rtnl_link_stats64 without also extending net_device_stats. Relax
> > > the BUILD_BUG_ON to only require that rtnl_link_stats64 is larger, and
> > > zero out all the stat counters that aren't present in net_device_stats.
> > >
> > > CC: Eric Dumazet <eduma...@google.com>
> > > CC: netdev@vger.kernel.org
> > > Signed-off-by: Jarod Wilson <ja...@redhat.com>
> > > ---
> > > Re-re-sending, hopefully getting the patch to the right list this time.
> > >
> > > net/core/dev.c | 13 +++++++++----
> > > 1 file changed, 9 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/net/core/dev.c b/net/core/dev.c
> > > index 8cba3d8..575a7df 100644
> > > --- a/net/core/dev.c
> > > +++ b/net/core/dev.c
> > > @@ -7253,25 +7253,30 @@ void netdev_run_todo(void)
> > > }
> > > }
> > >
> > > -/* Convert net_device_stats to rtnl_link_stats64. They have the same
> > > - * fields in the same order, with only the type differing.
> > > +/* Convert net_device_stats to rtnl_link_stats64. rtnl_link_stats64 has
> > > + * all the same fields in the same order as net_device_stats, with only
> > > + * the type differing, but rtnl_link_stats64 may have additional fields
> > > + * at the end for newer counters.
> > > */
> > > void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
> > > const struct net_device_stats *netdev_stats)
> > > {
> > > #if BITS_PER_LONG == 64
> > > - BUILD_BUG_ON(sizeof(*stats64) != sizeof(*netdev_stats));
> > > + BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats));
> > > memcpy(stats64, netdev_stats, sizeof(*stats64));
> > > #else
> > > size_t i, n = sizeof(*stats64) / sizeof(u64);
> > > const unsigned long *src = (const unsigned long *)netdev_stats;
> > > u64 *dst = (u64 *)stats64;
> > >
> > > - BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) !=
> > > + BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) >
> > > sizeof(*stats64) / sizeof(u64));
> > > for (i = 0; i < n; i++)
> > > dst[i] = src[i];
> > > #endif
> > > + /* zero out counters that only exist in rtnl_link_stats64 */
> > > + memset((char *)stats64 + sizeof(*netdev_stats), 0,
> > > + sizeof(*stats64) - sizeof(*netdev_stats));
> >
> > Are you sure it works on 32bit arches ?
>
> Ew, no, it won't work correctly on 32-bit. The for loop is going to copy
> data into dst from beyond the end of netdev_stats, and the range looks
> like it won't be right either, only half of the added stats64 space will
> get zeroed out. Okay, I'll fix that up correctly.
Completely untested as of yet, but I think something like the following
looks correct. I'll give it a spin as soon as I can.
diff --git a/net/core/dev.c b/net/core/dev.c
index 8cba3d8..65863e5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7253,24 +7253,31 @@ void netdev_run_todo(void)
}
}
-/* Convert net_device_stats to rtnl_link_stats64. They have the same
- * fields in the same order, with only the type differing.
+/* Convert net_device_stats to rtnl_link_stats64. rtnl_link_stats64 has
+ * all the same fields in the same order as net_device_stats, with only
+ * the type differing, but rtnl_link_stats64 may have additional fields
+ * at the end for newer counters.
*/
void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
const struct net_device_stats *netdev_stats)
{
#if BITS_PER_LONG == 64
- BUILD_BUG_ON(sizeof(*stats64) != sizeof(*netdev_stats));
+ BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats));
memcpy(stats64, netdev_stats, sizeof(*stats64));
+ /* zero out counters that only exist in rtnl_link_stats64 */
+ memset((char *)stats64 + sizeof(*netdev_stats), 0,
+ sizeof(*stats64) - sizeof(*netdev_stats));
#else
- size_t i, n = sizeof(*stats64) / sizeof(u64);
+ size_t i, n = sizeof(*netdev_stats) / sizeof(unsigned long);
const unsigned long *src = (const unsigned long *)netdev_stats;
u64 *dst = (u64 *)stats64;
- BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) !=
- sizeof(*stats64) / sizeof(u64));
+ BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));
for (i = 0; i < n; i++)
dst[i] = src[i];
+ /* zero out counters that only exist in rtnl_link_stats64 */
+ memset((char *)stats64 + n * sizeof(u64), 0,
+ sizeof(*stats64) - n * sizeof(u64));
#endif
}
EXPORT_SYMBOL(netdev_stats_to_stats64);
--
Jarod Wilson
ja...@redhat.com
