Re: [Xen-devel] [PATCH v2 4/5] xenstore: make memory report available via XS_CONTROL

[Juergen Gross <jgross@xxxxxxxx>]

On 22/02/17 13:36, Wei Liu wrote:
> On Tue, Feb 21, 2017 at 04:07:36PM +0100, Juergen Gross wrote:
>> Add a XS_CONTROL command to xenstored for doing a talloc report to a
>> file. Right now this is supported by specifying a command line option
>> when starting xenstored and sending a signal to the daemon to trigger
>> the report.
>>
>> To dump the report to the standard log file call:
>>
>> xenstore-control memreport
>>
>> To dump the report to a new file call:
>>
>> xenstore-control memreport <file>
>>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> ---
>>  tools/xenstore/xenstored_control.c | 36 ++++++++++++++++++++++++++++++++++++
>>  tools/xenstore/xenstored_core.c    |  2 +-
>>  tools/xenstore/xenstored_core.h    |  1 +
>>  3 files changed, 38 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/xenstore/xenstored_control.c 
>> b/tools/xenstore/xenstored_control.c
>> index c3587ad..b4ec6ce 100644
>> --- a/tools/xenstore/xenstored_control.c
>> +++ b/tools/xenstore/xenstored_control.c
>> @@ -76,6 +76,41 @@ static int do_control_logfile(void *ctx, struct 
>> connection *conn,
>>      return 0;
>>  }
>>  
>> +static int do_control_memreport(void *ctx, struct connection *conn,
>> +                            char **vec, int num)
>> +{
>> +    FILE *fp;
>> +    int fd;
>> +
>> +    if (num > 1)
>> +            return EINVAL;
>> +
>> +    if (num == 0) {
>> +            if (tracefd < 0) {
>> +                    if (!tracefile)
>> +                            return EBADF;
>> +                    fp = fopen(tracefile, "a");
>> +            } else {
>> +                    fd = dup(tracefd);
> 
> Why dup() the fd? Is it because you want to avoid tracefd becomes
> invalid under your feet?
> 

I want to be able to fclose() to get rid of the stream resources without
closing the log file.


Juergen

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