| Message ID | 1378408625-18415-1-git-send-email-jesse@nicira.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, Sep 5, 2013 at 9:17 PM, Jesse Gross <jesse@nicira.com> wrote: > --- a/net/openvswitch/flow.c > +++ b/net/openvswitch/flow.c > @@ -1981,6 +1981,7 @@ nla_put_failure: > * Returns zero if successful or a negative error code. */ > int ovs_flow_init(void) > { > + BUILD_BUG_ON(__alignof__(struct sw_flow_key) % __alignof__(long)); > -} __aligned(__alignof__(long)); > +} __aligned(BITS_PER_LONG/8); /* Ensure that we can do comparisons as longs. */ These don't match: the struct definition says aligned to 4 or 8 bytes, the check checks for a multiple of the alignment of "long", which is 2, 4 or 8. Anyway, BITS_PER_LONG/8 is always a multiple of __alignof__(long), so your check will never fail. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Jesse Gross <jesse@nicira.com> Date: Thu, 5 Sep 2013 12:17:05 -0700 > sw_flow_key alignment was declared as " __aligned(__alignof__(long))". > However, this breaks on the m68k architecture where long is 32 bit in > size but 16 bit aligned by default. This aligns to the size of a long to > ensure that we can always do comparsions in full long-sized chunks. It > also adds an additional build check to catch any reduction in alignment. > > CC: Andy Zhou <azhou@nicira.com> > Reported-by: Fengguang Wu <fengguang.wu@intel.com> > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> > Signed-off-by: Jesse Gross <jesse@nicira.com> Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c index ad1aeeb..fb36f85 100644 --- a/net/openvswitch/flow.c +++ b/net/openvswitch/flow.c @@ -1981,6 +1981,7 @@ nla_put_failure: * Returns zero if successful or a negative error code. */ int ovs_flow_init(void) { + BUILD_BUG_ON(__alignof__(struct sw_flow_key) % __alignof__(long)); BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long)); flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0, diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h index b65f885..212fbf7 100644 --- a/net/openvswitch/flow.h +++ b/net/openvswitch/flow.h @@ -125,7 +125,7 @@ struct sw_flow_key { } nd; } ipv6; }; -} __aligned(__alignof__(long)); +} __aligned(BITS_PER_LONG/8); /* Ensure that we can do comparisons as longs. */ struct sw_flow { struct rcu_head rcu;
sw_flow_key alignment was declared as " __aligned(__alignof__(long))". However, this breaks on the m68k architecture where long is 32 bit in size but 16 bit aligned by default. This aligns to the size of a long to ensure that we can always do comparsions in full long-sized chunks. It also adds an additional build check to catch any reduction in alignment. CC: Andy Zhou <azhou@nicira.com> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Jesse Gross <jesse@nicira.com> --- net/openvswitch/flow.c | 1 + net/openvswitch/flow.h | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)