Re: [PATCH bluez] bnep: don't error() if kernel lacks bnep module

Hi

On Fri, Sep 13, 2013 at 12:58 PM, Johan Hedberg [off-list ref] wrote:

Hi David,

On Fri, Sep 13, 2013, David Herrmann wrote:

quoted

On Fri, Sep 13, 2013 at 12:01 PM, Johan Hedberg [off-list ref] wrote:

quoted

Hi David,

On Fri, Sep 06, 2013, David Herrmann wrote:

quoted

If a user disables bnep kernel support, they normally do that on purpose.
It's misleading to print an error during module-startup in this situation.
Therefore, only print a hint that bnep-support is missing if
EPROTONOSUPPORT is returned by the kernel.

Furthermore, allow modules to forward ENOSYS as error to bluetoothd core
to handle it as "module is not compatible with system setup" instead of an
error. ENOSYS is commonly used to signal "missing kernel infrastructure"
so it seems appropriate here.
---
 profiles/network/common.c  |  7 ++++++-
 profiles/network/manager.c | 17 ++++++++++++++---
 src/plugin.c               | 11 +++++++++--
 3 files changed, 29 insertions(+), 6 deletions(-)

First of all, sorry for the delay with reviewing this. I forgot about it
and only bumped into it now when checking what I'd missed from the last
month in my linux-bluetooth folder.

quoted

diff --git a/profiles/network/common.c b/profiles/network/common.c
index e069892..17bff30 100644
--- a/profiles/network/common.c
+++ b/profiles/network/common.c

@@ -110,8 +110,13 @@ int bnep_init(void)

      if (ctl < 0) {
              int err = -errno;
-             error("Failed to open control socket: %s (%d)",
+
+             if (err == -EPROTONOSUPPORT)
+                     info("kernel lacks bnep-protocol support");

I think warn() might be more appropriate here.

Using warn() defeats the whole purpose of this patch. I want to run
bluetoothd without getting a warning or error, and obviously, there is
nothing to warn _me_ about. I'm ok if you want err() or warn() here so
other users get warned, but in that case we should just drop the
patch.

I thought the main idea was to have a clearer log message when the
module is not there. None of the warn/error/info messages can be
suppressed (unlike DBG which is off by default). To me warn() seems more
appropriate than info() since it's meaning is "this is something that
may or may not be of concern to the user".

It's not about suppressing messages. It's about putting proper
attributes on them. If I look at my system-log, I am usually only
interested in errors and warnings. And each of them needs my attention
to get fixed. Otherwise, the purpose of an error or warning is missed.
If every running daemon spits warnings to the log which I cannot
"fix", warnings will no longer be any special. Same for errors,
obviously.

So imho every warning should be "fixable" by the administrator. And in
this case I don't think enabling BNEP in the kernel is the appropriate
fix. Instead, if an administrator disables BNEP, bluetoothd should
interpret that as a "configuration-choice".

quoted

So it's up to you to decide. If info() is ok, I will fix the issues
you mentioned below, otherwise just drop it.

I do think the patch has value even though info() is not used by having
an understandable log message for what's going on.

In that case I will resend it. Please let me know whether to use
info() or warn().

Thanks
David