| Message ID | 1283436908-10744-1-git-send-email-xiaosuo@gmail.com |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
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? -- 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
On Thu, Sep 16, 2010 at 1:32 AM, Patrick McHardy <kaber@trash.net> 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
On Sunday 2010-09-19 07:58, Changli Gao wrote: >On Thu, Sep 16, 2010 at 1:32 AM, Patrick McHardy <kaber@trash.net> 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: I support this. -- 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
Am 02.10.2010 01:57, schrieb Jan Engelhardt: > On Sunday 2010-09-19 07:58, Changli Gao wrote: > >> On Thu, Sep 16, 2010 at 1:32 AM, Patrick McHardy <kaber@trash.net> 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: > > I support this. Yeah, it seems reasonable, although I don't like changing things without a concrete reason. Anyways, applied, thanks everyone. -- 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/netfilter/core.c b/net/netfilter/core.c index 78b505d..8f014f2 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -105,10 +105,8 @@ EXPORT_SYMBOL(nf_register_hooks); void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n) { - unsigned int i; - - for (i = 0; i < n; i++) - nf_unregister_hook(®[i]); + while (n-- > 0) + nf_unregister_hook(®[n]); } EXPORT_SYMBOL(nf_unregister_hooks); diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index e34622f..8046350 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -116,10 +116,8 @@ EXPORT_SYMBOL(xt_register_targets); void xt_unregister_targets(struct xt_target *target, unsigned int n) { - unsigned int i; - - for (i = 0; i < n; i++) - xt_unregister_target(&target[i]); + while (n-- > 0) + xt_unregister_target(&target[n]); } EXPORT_SYMBOL(xt_unregister_targets); @@ -174,10 +172,8 @@ EXPORT_SYMBOL(xt_register_matches); void xt_unregister_matches(struct xt_match *match, unsigned int n) { - unsigned int i; - - for (i = 0; i < n; i++) - xt_unregister_match(&match[i]); + while (n-- > 0) + xt_unregister_match(&match[n]); } EXPORT_SYMBOL(xt_unregister_matches);
Since we register nf hooks, matches and targets in order, we'd better unregister them in the reverse order. Signed-off-by: Changli Gao <xiaosuo@gmail.com> --- net/netfilter/core.c | 6 ++---- net/netfilter/x_tables.c | 12 ++++-------- 2 files changed, 6 insertions(+), 12 deletions(-) -- 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