| Message ID | 201012150801.oBF81EVm047830@www262.sakura.ne.jp |
|---|---|
| State | Rejected, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Date: Wed, 15 Dec 2010 17:01:14 +0900 > [2.6.37-rc5] Build error on parisc. > > Commit 5635c10d "net: make sure struct dst_entry refcount is aligned on 64 bytes" > uses manual padding. I triggered BUILD_BUG_ON() when using > http://kernel.org/pub/tools/crosstool/files/bin/i686/4.5.1/i686-gcc-4.5.1-nolibc_hppa64-linux.tar.bz2 . > > make -s CROSS_COMPILE=hppa64-linux- ARCH=parisc > > include/net/dst.h: In function 'dst_hold': > include/net/dst.h:161:2: error: negative width in bit-field '<anonymous>' > > I think below patch can fix the error but that commit says that we cannot use > __atribute((aligned)). Why? We don't want to create holes of unused space in the structure, we want to know exactly how every byte of space is being used so nothing is wasted when all features are enabed. -- 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
Le mercredi 15 décembre 2010 à 10:19 -0800, David Miller a écrit : > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Date: Wed, 15 Dec 2010 17:01:14 +0900 > > > [2.6.37-rc5] Build error on parisc. > > > > Commit 5635c10d "net: make sure struct dst_entry refcount is aligned on 64 bytes" > > uses manual padding. I triggered BUILD_BUG_ON() when using > > http://kernel.org/pub/tools/crosstool/files/bin/i686/4.5.1/i686-gcc-4.5.1-nolibc_hppa64-linux.tar.bz2 . > > > > make -s CROSS_COMPILE=hppa64-linux- ARCH=parisc > > > > include/net/dst.h: In function 'dst_hold': > > include/net/dst.h:161:2: error: negative width in bit-field '<anonymous>' > > > > I think below patch can fix the error but that commit says that we cannot use > > __atribute((aligned)). Why? > > We don't want to create holes of unused space in the structure, we want > to know exactly how every byte of space is being used so nothing is > wasted when all features are enabed. Yes, sorry for missing your mail Tetsuo. -- 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/include/net/dst.h b/include/net/dst.h index ffe9cb7..02df303 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -62,8 +62,6 @@ struct dst_entry { struct hh_cache *hh; #ifdef CONFIG_XFRM struct xfrm_state *xfrm; -#else - void *__pad1; #endif int (*input)(struct sk_buff*); int (*output)(struct sk_buff*); @@ -74,23 +72,15 @@ struct dst_entry { #ifdef CONFIG_NET_CLS_ROUTE __u32 tclassid; -#else - __u32 __pad2; -#endif - - - /* - * Align __refcnt to a 64 bytes alignment - * (L1_CACHE_SIZE would be too much) - */ -#ifdef CONFIG_64BIT - long __pad_to_align_refcnt[1]; #endif /* * __refcnt wants to be on a different cache line from * input/output/ops or performance tanks badly + * + * Align __refcnt to a 64 bytes alignment + * (L1_CACHE_SIZE would be too much) */ - atomic_t __refcnt; /* client references */ + atomic_t __refcnt __aligned(64); /* client references */ int __use; unsigned long lastuse; union { @@ -154,11 +144,6 @@ dst_metric_locked(struct dst_entry *dst, int metric) static inline void dst_hold(struct dst_entry * dst) { - /* - * If your kernel compilation stops here, please check - * __pad_to_align_refcnt declaration in struct dst_entry - */ - BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); atomic_inc(&dst->__refcnt); }