Re: [Qemu-devel] [RFC PATCH v2 02/10] Jhash: add linux kernel jhashtable in qemu

[Dr. David Alan Gilbert]

* Zhang Chen (address@hidden) wrote:
> 
> 
> On 01/11/2016 08:50 PM, Dr. David Alan Gilbert wrote:
> >* Zhang Chen (address@hidden) wrote:
> >>
> >>On 01/08/2016 08:08 PM, Dr. David Alan Gilbert wrote:
> >>>* Zhang Chen (address@hidden) wrote:
> >>>>From: zhangchen <address@hidden>
> >>>>
> >>>>Jhash used by colo-proxy to save and lookup
> >>>>net connection info
> >>>>
> >>>>Signed-off-by: zhangchen <address@hidden>
> >>>>Signed-off-by: zhanghailiang <address@hidden>
> >>>>---
> >>>>  include/qemu/jhash.h | 61 
> >>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >>>>  1 file changed, 61 insertions(+)
> >>>>  create mode 100644 include/qemu/jhash.h
> >>>>
> >>>>diff --git a/include/qemu/jhash.h b/include/qemu/jhash.h
> >>>>new file mode 100644
> >>>>index 0000000..5b82d02
> >>>>--- /dev/null
> >>>>+++ b/include/qemu/jhash.h
> >>>>@@ -0,0 +1,61 @@
> >>>>+/* jhash.h: Jenkins hash support.
> >>>>+  *
> >>>>+  * Copyright (C) 2006. Bob Jenkins (address@hidden)
> >>>>+  *
> >>>>+  * http://burtleburtle.net/bob/hash/
> >>>>+  *
> >>>>+  * These are the credits from Bob's sources:
> >>>>+  *
> >>>>+  * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
> >>>>+  *
> >>>>+  * These are functions for producing 32-bit hashes for hash table 
> >>>>lookup.
> >>>>+  * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and 
> >>>>final()
> >>>>+  * are externally useful functions.  Routines to test the hash are
> >>>>+included
> >>>>+  * if SELF_TEST is defined.  You can use this free for any purpose.
> >>>>+It's in
> >>>>+  * the public domain.  It has no warranty.
> >>>>+  *
> >>>>+  * Copyright (C) 2009-2010 Jozsef Kadlecsik (address@hidden)
> >>>>+  *
> >>>>+  * I've modified Bob's hash to be useful in the Linux kernel, and
> >>>>+  * any bugs present are my fault.
> >>>>+  * Jozsef
> >>>>+  */
> >>>>+
> >>>>+#ifndef QEMU_JHASH_H__
> >>>>+#define QEMU_JHASH_H__
> >>>>+
> >>>>+#include "qemu/bitopt.h"
> >>>That does not build, the header in qemu is bitop*s*.h.
> >>>
> >>>Dave
> >>I'm very sorry for it, fix it to
> >>
> >>#include "qemu/bitopts.h"
> >No! It's:
> >
> >#include "qemu/bitops.h"
> >
> >Please at least build test this code!
> >
> >Dave
> 
> Fix it to #include "qemu/bitops.h"
> I have rebuild this code,but qemu makefile did't check the .h
> I don't know whether it is a qemu bug.
> you can try change it to #include "qemu/bitops.h" and make.
> then change it to #include "qemu/bitopts.h" and make.
> repeat it twice, now, you can change it to #include "everything"
> in jhash.h. gcc don't check the .h and report error.////

gcc/makefile don't check these things; it's when you include the
next patch in your series, that #include "qemu/jhash.h" in colo-proxy.c
which is where it will break.

Dave

> 
> 
> Thanks
> zhangchen
> 
> 
> >>Thanks
> >>zhangchen
> >>
> >>
> >>>>+
> >>>>+/*
> >>>>+ * hashtable relation copy from linux kernel jhash
> >>>>+ */
> >>>>+
> >>>>+/* __jhash_mix -- mix 3 32-bit values reversibly. */
> >>>>+#define __jhash_mix(a, b, c)                \
> >>>>+{                                           \
> >>>>+    a -= c;  a ^= rol32(c, 4);  c += b;     \
> >>>>+    b -= a;  b ^= rol32(a, 6);  a += c;     \
> >>>>+    c -= b;  c ^= rol32(b, 8);  b += a;     \
> >>>>+    a -= c;  a ^= rol32(c, 16); c += b;     \
> >>>>+    b -= a;  b ^= rol32(a, 19); a += c;     \
> >>>>+    c -= b;  c ^= rol32(b, 4);  b += a;     \
> >>>>+}
> >>>>+
> >>>>+/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
> >>>>+#define __jhash_final(a, b, c)  \
> >>>>+{                               \
> >>>>+    c ^= b; c -= rol32(b, 14);  \
> >>>>+    a ^= c; a -= rol32(c, 11);  \
> >>>>+    b ^= a; b -= rol32(a, 25);  \
> >>>>+    c ^= b; c -= rol32(b, 16);  \
> >>>>+    a ^= c; a -= rol32(c, 4);   \
> >>>>+    b ^= a; b -= rol32(a, 14);  \
> >>>>+    c ^= b; c -= rol32(b, 24);  \
> >>>>+}
> >>>>+
> >>>>+/* An arbitrary initial parameter */
> >>>>+#define JHASH_INITVAL           0xdeadbeef
> >>>>+
> >>>>+#endif /* QEMU_JHASH_H__ */
> >>>>-- 
> >>>>1.9.1
> >>>>
> >>>>
> >>>>
> >>>--
> >>>Dr. David Alan Gilbert / address@hidden / Manchester, UK
> >>>
> >>>
> >>>.
> >>>
> >>-- 
> >>Thanks
> >>zhangchen
> >>
> >>
> >>
> >--
> >Dr. David Alan Gilbert / address@hidden / Manchester, UK
> >
> >
> >.
> >
> 
> -- 
> Thanks
> zhangchen
> 
> 
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK