linux-kernel - Re: [PATCH v3 2/5] bpf: Simplify bpf_load_program() error handling in the library

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Date:   Wed, 8 Feb 2017 21:03:48 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     "Wangnan (F)" <wangnan0@...wei.com>, linux-kernel@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Joe Stringer <joe@....org>, netdev@...r.kernel.org
Subject: Re: [PATCH v3 2/5] bpf: Simplify bpf_load_program() error handling in
 the library


On 08/02/2017 03:35, Wangnan (F) wrote:
> 
> 
> On 2017/2/8 4:56, Mickaël Salaün wrote:
>> Do not call a second time bpf(2) when a program load failed.
> 
> BPF_PROG_LOAD should success most of the time. Setting log_level to
> 0 by default and require log buffer when failure can make it faster
> in normal case.

OK, I'm not sure if this is relevant for a test but I'm going to remove
this patch.

Thanks

> 
> Thank you.
> 
>> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
>> Cc: Alexei Starovoitov <ast@...com>
>> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
>> Cc: Daniel Borkmann <daniel@...earbox.net>
>> Cc: Wang Nan <wangnan0@...wei.com>
>> ---
>>   tools/lib/bpf/bpf.c | 18 ++++++------------
>>   1 file changed, 6 insertions(+), 12 deletions(-)
>>
>> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
>> index 3ddb58a36d3c..fda3f494f1cd 100644
>> --- a/tools/lib/bpf/bpf.c
>> +++ b/tools/lib/bpf/bpf.c
>> @@ -73,7 +73,6 @@ int bpf_load_program(enum bpf_prog_type type, struct
>> bpf_insn *insns,
>>                size_t insns_cnt, char *license,
>>                __u32 kern_version, char *log_buf, size_t log_buf_sz)
>>   {
>> -    int fd;
>>       union bpf_attr attr;
>>         bzero(&attr, sizeof(attr));
>> @@ -81,20 +80,15 @@ int bpf_load_program(enum bpf_prog_type type,
>> struct bpf_insn *insns,
>>       attr.insn_cnt = (__u32)insns_cnt;
>>       attr.insns = ptr_to_u64(insns);
>>       attr.license = ptr_to_u64(license);
>> -    attr.log_buf = ptr_to_u64(NULL);
>> -    attr.log_size = 0;
>> -    attr.log_level = 0;
>> +    attr.log_buf = ptr_to_u64(log_buf);
>> +    attr.log_size = log_buf_sz;
>>       attr.kern_version = kern_version;
>>   -    fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
>> -    if (fd >= 0 || !log_buf || !log_buf_sz)
>> -        return fd;
>> +    if (log_buf && log_buf_sz > 0) {
>> +        attr.log_level = 1;
>> +        log_buf[0] = 0;
>> +    }
>>   -    /* Try again with log */
>> -    attr.log_buf = ptr_to_u64(log_buf);
>> -    attr.log_size = log_buf_sz;
>> -    attr.log_level = 1;
>> -    log_buf[0] = 0;
>>       return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
>>   }
>>   
> 
> 
> 



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