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

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Feb 22, 2017 at 01:43:27PM +0100, Juergen Gross wrote:
> 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.
> 

Oh, right. I missed that aspect. Could you please add a comment for that
please.

> 
> Juergen

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