On Thu, Sep 16, 2010 at 1:32 AM, Patrick McHardy <kaber@xxxxxxxxx> wrote:
> Am 02.09.2010 16:15, schrieb Changli Gao:
>> Since we register nf hooks, matches and targets in order, we'd better
>> unregister them in the reverse order.
>
> Why? Is there a specific bug you've noticed?
>
No, there isn't any bug. I just think unregistering them in the
reverse order is more resonable, like the rollback when failing. And
the code patched generates less object:
The original:
00000000000009c9 <xt_unregister_matches>:
9c9: 55 push %rbp
9ca: 48 89 e5 mov %rsp,%rbp
9cd: 41 55 push %r13
9cf: 41 89 f5 mov %esi,%r13d
9d2: 41 54 push %r12
9d4: 49 89 fc mov %rdi,%r12
9d7: 53 push %rbx
9d8: 31 db xor %ebx,%ebx
9da: 48 83 ec 08 sub $0x8,%rsp
9de: eb 0e jmp 9ee <xt_unregister_matches+0x25>
9e0: 4c 89 e7 mov %r12,%rdi
9e3: ff c3 inc %ebx
9e5: 49 83 c4 78 add $0x78,%r12
9e9: e8 00 00 00 00 callq 9ee <xt_unregister_matches+0x25>
9ee: 44 39 eb cmp %r13d,%ebx
9f1: 72 ed jb 9e0 <xt_unregister_matches+0x17>
9f3: 41 59 pop %r9
9f5: 5b pop %rbx
9f6: 41 5c pop %r12
9f8: 41 5d pop %r13
9fa: c9 leaveq
9fb: c3 retq
The patched:
00000000000009c9 <xt_unregister_matches>:
9c9: 55 push %rbp
9ca: 48 89 e5 mov %rsp,%rbp
9cd: 41 54 push %r12
9cf: 41 89 f4 mov %esi,%r12d
9d2: 53 push %rbx
9d3: 48 89 fb mov %rdi,%rbx
9d6: eb 13 jmp 9eb <xt_unregister_matches+0x22>
9d8: 41 ff cc dec %r12d
9db: 44 89 e7 mov %r12d,%edi
9de: 48 6b ff 78 imul $0x78,%rdi,%rdi
9e2: 48 8d 3c 3b lea (%rbx,%rdi,1),%rdi
9e6: e8 00 00 00 00 callq 9eb <xt_unregister_matches+0x22>
9eb: 45 85 e4 test %r12d,%r12d
9ee: 75 e8 jne 9d8 <xt_unregister_matches+0xf>
9f0: 5b pop %rbx
9f1: 41 5c pop %r12
9f3: c9 leaveq
9f4: c3 retq
--
Regards,
Changli Gao(xiaosuo@xxxxxxxxx)
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