[PATCH] xl: don't emit misleading daemon pid message

[PATCH] xl: don't emit misleading daemon pid message

[Matthew Daley]

After creating a domain, xl forks off a process to handle domain events
(shutdown, disk eject, ...). It prints out the pid of the process
created by the fork to stdout. However, the newly forked process soon
after calls daemon(), which itself forks once more (and exit()s the
original process). This means that the pid printed out is not the pid of
the actual process which remains in the background after all is said and
done, instead it is the pid of the transient process that exists between
xl's fork() and the fork'd process's daemon() call.

We could resolve this by printing the correct pid, ie. by open-coding
daemon() (we already do most of the heavy lifting it does ourselves by
fiddling with the standard fds). However, since no-one seems to be
complaining about the misleading message to begin with, and since it
seems like a pointless message anyway, just remove it outright instead.

Signed-off-by: Matthew Daley <mattjd@gmail.com>
---
Perhaps the only other remaining `xl create` stdout message, 'Parsing config
from ...' could be removed too?

 tools/libxl/xl_cmdimpl.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index a8261be..fddaa80 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -2140,8 +2140,6 @@ start:
 
         child1 = xl_fork(child_waitdaemon);
         if (child1) {
-            printf("Daemon running with PID %d\n", child1);
-
             for (;;) {
                 got_child = xl_waitpid(child_waitdaemon, &status, 0);
                 if (got_child == child1) break;
-- 
1.7.10.4

Re: [PATCH] xl: don't emit misleading daemon pid message

[Ian Jackson]

Matthew Daley writes ("[PATCH] xl: don't emit misleading daemon pid message"):
> After creating a domain, xl forks off a process to handle domain events
> (shutdown, disk eject, ...). It prints out the pid of the process
> created by the fork to stdout. However, the newly forked process soon
> after calls daemon(), which itself forks once more (and exit()s the
> original process). This means that the pid printed out is not the pid of
> the actual process which remains in the background after all is said and
> done, instead it is the pid of the transient process that exists between
> xl's fork() and the fork'd process's daemon() call.
> 
> We could resolve this by printing the correct pid, ie. by open-coding
> daemon() (we already do most of the heavy lifting it does ourselves by
> fiddling with the standard fds). However, since no-one seems to be
> complaining about the misleading message to begin with, and since it
> seems like a pointless message anyway, just remove it outright instead.
> 
> Signed-off-by: Matthew Daley <mattjd@gmail.com>

Thanks,
Ian.

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>