Re: [Xen-devel] [PATCH for-4.6] xenstored: log tdb message via xenstored's logging mechanisms

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Jan 08, 2015 at 12:33:29PM +0000, Ian Campbell wrote:
> ping.
> 
> On Mon, 2014-12-15 at 13:18 +0000, Ian Campbell wrote:
> > TDB provides us with a callback for this purpose. Use it in both
> > xenstored and xs_tdb_dump.
> > 
> > While at it make the existing log() macro tollerate memory failures.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> >  tools/xenstore/xenstored_core.c |   39 
> > +++++++++++++++++++++++++++++++++------
> >  tools/xenstore/xs_tdb_dump.c    |   12 +++++++++++-
> >  2 files changed, 44 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/xenstore/xenstored_core.c 
> > b/tools/xenstore/xenstored_core.c
> > index 4eaff57..3fd9a20 100644
> > --- a/tools/xenstore/xenstored_core.c
> > +++ b/tools/xenstore/xenstored_core.c
> > @@ -89,9 +89,14 @@ static void check_store(void);
> >  #define log(...)                                                   \
> >     do {                                                            \
> >             char *s = talloc_asprintf(NULL, __VA_ARGS__);           \
> > -           trace("%s\n", s);                                       \
> > -           syslog(LOG_ERR, "%s",  s);                              \
> > -           talloc_free(s);                                         \
> > +           if (s) {                                                \
> > +                   trace("%s\n", s);                               \
> > +                   syslog(LOG_ERR, "%s",  s);                      \
> > +                   talloc_free(s);                                 \
> > +           } else {                                                \
> > +                   trace("talloc failure during logging\n");       \
> > +                   syslog(LOG_ERR, "talloc failure during logging\n"); \
> > +           }                                                       \

talloc_free can tolerate NULL pointer.

> >     } while (0)
> >  
[...]
> > +           tdb_ctx = tdb_open_ex(tdbname, 0, tdb_flags, O_RDWR, 0,
> > +                                 &tdb_logger, NULL);
[...]
> > +           tdb_ctx = tdb_open_ex(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT,
> > +                                 0640, &tdb_logger, NULL);
[...]
> > +   tdb = tdb_open_ex(talloc_strdup(NULL, argv[1]), 0, 0, O_RDONLY, 0,
> > +                     tdb_logger, NULL);

Should be &tdb_logger?

Wei.

> >     if (!tdb)
> >             barf_perror("Could not open %s", argv[1]);
> >  
> 

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