linux-kernel - Re: perf-core build fails on powerpc

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Date:   Wed, 14 Mar 2018 09:23:27 +0000
From:   John Garry <john.garry@...wei.com>
To:     Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
CC:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Jiri Olsa" <jolsa@...hat.com>
Subject: Re: perf-core build fails on powerpc

On 14/03/2018 07:10, John Garry wrote:
> On 13/03/2018 21:18, Sukadev Bhattiprolu wrote:
>> John Garry [john.garry@...wei.com] wrote:
>>> On 13/03/2018 20:10, Sukadev Bhattiprolu wrote:
>>>
>>>> Hi John,
>>>>
>>>> I have an xfs file system which seems to have d_type == DT_UNKNOWN
>>>> for all
>>>> entries in 'tools/perf/pmu-events/arch/power8'! readdir(3) says
>>>> ->d_type
>>>> may not be supported by all file systems.
>>>>
>>>> Not relying on ->d_type seems to fix it:
>>>>
>>>
>>> Hi Sukadev,
>>>
>>> Thanks for debugging this. Jiri Olsa (cc'ed) warned me on this, so I
>>> did add
>>> the check for d_type == DT_UNKNOWN.
>>>
>>> But, if all files have d_type == DT_UNKNOWN, you're code would from
>>> visual
>>> observation look to be same as mine (apart from check for '.' or '..'
>>> filename, which I would say is already covered by stat() and
>>> S_ISDIR()). Or
>>> is d_type value just unreliable?
>>
>> In the current code and with DT_UNKNOWN, is_leaf_dir() returns false when
>> it sees the "." or ".." entries right? In the new code, we skip those and
>> return false only if we find some other directory.
>>
>
> OK, that's the real issue, being the "." and ".." entries.
>
> @Arnaldo, I'll try to send a fix for this today. I just need to make an
> xfs to test. Sorry for the hassle.
>

Hi Sukadev,

Even with the xfs I have created I still don't see DT_UNKNOWN. So can 
you kindly test this change for me:

diff --git a/tools/perf/pmu-events/jevents.c 
b/tools/perf/pmu-events/jevents.c
index 1c018445e757..9f712dafa0b2 100644
--- a/tools/perf/pmu-events/jevents.c
+++ b/tools/perf/pmu-events/jevents.c
@@ -873,7 +873,10 @@ static int is_leaf_dir(const char *fpath)
                 return 0;

         while ((dir = readdir(d)) != NULL) {
-               if (dir->d_type == DT_DIR && dir->d_name[0] != '.') {
+               if (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, ".."))
+                    continue;
+
+               if (dir->d_type == DT_DIR) {
                         res = 0;
                         break;
                 } else if (dir->d_type == DT_UNKNOWN) {


It's quite similar to your change, except keeping the check for DT_DIR.

Much appreciated,
John

> John
>
>> Thanks,
>>
>> Sukadev
>>
>>
>>
>