On Thu, Mar 26 2020, Christophe JAILLET wrote:
> Le 25/03/2020 à 23:53, NeilBrown a écrit :
>> Can I suggest something more like this:
>> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
>> index de3c077733a7..0292f45b70f6 100644
>> --- a/net/sunrpc/svc_xprt.c
>> +++ b/net/sunrpc/svc_xprt.c
>> @@ -115,16 +115,9 @@ int svc_print_xprts(char *buf, int maxlen)
>> buf[0] = '\0';
>>
>> spin_lock(&svc_xprt_class_lock);
>> - list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
>> - int slen;
>> -
>> - sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
>> - slen = strlen(tmpstr);
>> - if (len + slen > maxlen)
>> - break;
>> - len += slen;
>> - strcat(buf, tmpstr);
>> - }
>> + list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list)
>> + len += scnprintf(buf + len, maxlen - len, "%s %d\n",
>> + xcl->xcl_name, xcl->xcl_max_payload);
>> spin_unlock(&svc_xprt_class_lock);
>>
>> return len;
>>
>> NeilBrown
>
> Hi,
>
> this was what I suggested in the patch:
> ---
> This patch should have no functional change.
> We could go further, use scnprintf and write directly in the
> destination
> buffer. However, this could lead to a truncated last line.
> ---
Sorry - I missed that.
So add
end = strrchr(tmpstr, '\n');
if (end)
end[1] = 0;
else
tmpstr[0] = 0;
or maybe something like
list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
int l = snprintf(buf + len, maxlen - len, "%s %d\n",
xcl->xcl_name, xcl->xcl_max_payload);
if (l < maxlen - len)
len += l;
}
buf[len] = 0;
There really is no need to have the secondary buffer, and I think doing
so just complicates the code.
That last version is a change of behaviour in that it will skip over
lines that are too long, rather than aborting on the first one.
I don't know which is preferred.
Thanks,
NeilBrown
>
> And Chuck Lever confirmed that:
> That's exactly what this function is trying to avoid. As part of any
> change in this area, it would be good to replace the current block
> comment before this function with a Doxygen-format comment that
> documents that goal.
>
> So, I will only send a V2 based on comments already received.
>
> CJ
> On Mar 26, 2020, at 5:44 PM, NeilBrown <[email protected]> wrote:
>
> On Thu, Mar 26 2020, Christophe JAILLET wrote:
>
>> Le 25/03/2020 à 23:53, NeilBrown a écrit :
>>> Can I suggest something more like this:
>>> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
>>> index de3c077733a7..0292f45b70f6 100644
>>> --- a/net/sunrpc/svc_xprt.c
>>> +++ b/net/sunrpc/svc_xprt.c
>>> @@ -115,16 +115,9 @@ int svc_print_xprts(char *buf, int maxlen)
>>> buf[0] = '\0';
>>>
>>> spin_lock(&svc_xprt_class_lock);
>>> - list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
>>> - int slen;
>>> -
>>> - sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
>>> - slen = strlen(tmpstr);
>>> - if (len + slen > maxlen)
>>> - break;
>>> - len += slen;
>>> - strcat(buf, tmpstr);
>>> - }
>>> + list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list)
>>> + len += scnprintf(buf + len, maxlen - len, "%s %d\n",
>>> + xcl->xcl_name, xcl->xcl_max_payload);
>>> spin_unlock(&svc_xprt_class_lock);
>>>
>>> return len;
>>>
>>> NeilBrown
>>
>> Hi,
>>
>> this was what I suggested in the patch:
>> ---
>> This patch should have no functional change.
>> We could go further, use scnprintf and write directly in the
>> destination
>> buffer. However, this could lead to a truncated last line.
>> ---
>
> Sorry - I missed that.
> So add
>
> end = strrchr(tmpstr, '\n');
> if (end)
> end[1] = 0;
> else
> tmpstr[0] = 0;
>
> or maybe something like
> list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
> int l = snprintf(buf + len, maxlen - len, "%s %d\n",
> xcl->xcl_name, xcl->xcl_max_payload);
> if (l < maxlen - len)
> len += l;
> }
> buf[len] = 0;
>
> There really is no need to have the secondary buffer, and I think doing
> so just complicates the code.
In the interest of getting this fix into the upcoming merge window, let's
stick with the temporary buffer approach. Thanks!
--
Chuck Lever