From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wang Weidong Subject: Re: [PATCH v2] sctp: loading sctp when load sctp_probe Date: Mon, 16 Dec 2013 22:14:55 +0800 Message-ID: <52AF0ADF.7030704@gmail.com> References: <52AA783A.7090502@huawei.com> <20131213122605.GA23384@hmsreliant.think-freely.org> <52AE69A4.7090806@huawei.com> <20131216134814.GA19809@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Vlad Yasevich , David Miller , netdev@vger.kernel.org, linux-sctp@vger.kernel.org To: Neil Horman Return-path: Received: from mail-pa0-f44.google.com ([209.85.220.44]:36100 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753809Ab3LPOOb (ORCPT ); Mon, 16 Dec 2013 09:14:31 -0500 In-Reply-To: <20131216134814.GA19809@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Wang Weidong On 2013/12/16 21:48, Neil Horman wrote: > On Mon, Dec 16, 2013 at 10:47:00AM +0800, Wang Weidong wrote: >> On 2013/12/13 20:26, Neil Horman wrote: >>> On Fri, Dec 13, 2013 at 11:00:10AM +0800, Wang Weidong wrote: >>>> when I modprobe sctp_probe, it failed with "FATAL: ". I found that >>>> sctp should load before sctp_probe register jprobe. So I add a >>>> sctp_setup_jprobe for loading 'sctp' when first failed to register >>>> jprobe, just do this similar to dccp_probe. >>>> >>>> v2: add MODULE_SOFTDEP and check of request_module, as suggested by Neil >>>> >>>> Signed-off-by: Wang Weidong >>>> --- >>>> net/sctp/probe.c | 17 ++++++++++++++++- >>>> 1 file changed, 16 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/net/sctp/probe.c b/net/sctp/probe.c >>>> index 53c452e..5e68b94 100644 >>>> --- a/net/sctp/probe.c >>>> +++ b/net/sctp/probe.c >>>> @@ -38,6 +38,7 @@ >>>> #include >>>> #include >>>> >>>> +MODULE_SOFTDEP("pre: sctp"); >>>> MODULE_AUTHOR("Wei Yongjun "); >>>> MODULE_DESCRIPTION("SCTP snooper"); >>>> MODULE_LICENSE("GPL"); >>>> @@ -182,6 +183,20 @@ static struct jprobe sctp_recv_probe = { >>>> .entry = jsctp_sf_eat_sack, >>>> }; >>>> >>>> +static __init int sctp_setup_jprobe(void) >>>> +{ >>>> + int ret = register_jprobe(&sctp_recv_probe); >>>> + >>>> + if (ret) { >>>> + if (request_module("sctp")) >>>> + goto out; >>>> + ret = register_jprobe(&sctp_recv_probe); >>>> + } >>>> + >>>> +out: >>>> + return ret; >>>> +} >>>> + >>>> static __init int sctpprobe_init(void) >>>> { >>>> int ret = -ENOMEM; >>>> @@ -202,7 +217,7 @@ static __init int sctpprobe_init(void) >>>> &sctpprobe_fops)) >>>> goto free_kfifo; >>>> >>>> - ret = register_jprobe(&sctp_recv_probe); >>>> + ret = sctp_setup_jprobe(); >>> You don't need to create your own function for this, you can collapse it down to >>> a call to try_then_request_module(regitser_jprobe(...), "sctp"); >>> Neil >>> >> Hi Neil, >> >> I try to use try_then_request_module(!regitser_jprobe(...), "sctp"); I found that if >> I used this, I couldn't get the ture value which returned by register_jprobe(). Is the >> returned value not important? The problem("if sctp.ko doesn't exist") you had pointed out >> is exist as well. >> >> Regards. >> Wang > > Not sure I follow. There appear to be lots of examples in the kernel where I do this just like the dccp/probe.c do. So I think it can be an example. > exactly what you are trying to do is done. try_then_request_module calls your > requested method, and if it returns non-zero, calls request_module, then calls No actually. Just look the definition: #define try_then_request_module(x, mod...) \ ((x) ?: (__request_module(true, mod), (x))) if x return non-zero, it will return the value, not call request_module. > your requested method again, returning the final result. What problem are you > running into? > Neil > So I only can use it like this: try_then_request_module(!regitser_jprobe(...), "sctp"); when register_jprobe return 0 indicates success, I get the value is 1. It is OK. when register_jprobe is non-zero indicates failed, then calls request_module, and last calls register_jprobe. Here, 1)maybe it will failed return non-zero, what I get the value is !register_jprobe is 0 with losing the value. 2)request_module failed with the sctp is not exist, it will do the register_jprobe as well. Is there I am wrong somewhere? Regards. Wang >>> >>>> if (ret) >>>> goto remove_proc; >>>> >>> >>> . >>> >> >> >> > -- > 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 >