Subject: Re: [PATCH v2] sctp: loading sctp when load sctp_probe

From: Wang Weidong <[email-masked]>
Date: Mon, 16 Dec 2013 10:47:00 +0800

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 <[email-masked]>
>> ---
>>  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 <net/sctp/sctp.h>
>>  #include <net/sctp/sm.h>
>>  
>> +MODULE_SOFTDEP("pre: sctp");
>>  MODULE_AUTHOR("Wei Yongjun <[email-masked]>");
>>  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
>>  	if (ret)
>>  		goto remove_proc;
> .