From: Tobias Waldekranz <tobias@waldekranz•com>
To: Jakub Kicinski <kuba@kernel•org>
Cc: davem@davemloft•net, jiri@resnulli•us, ivecera@redhat•com,
netdev@vger•kernel.org, roopa@nvidia•com, razor@blackwall•org,
bridge@lists•linux.dev, rostedt@goodmis•org, mhiramat@kernel•org,
linux-trace-kernel@vger•kernel.org
Subject: Re: [PATCH v2 net-next 2/5] net: switchdev: Add helpers to display switchdev objects as strings
Date: Fri, 02 Feb 2024 08:48:39 +0100 [thread overview]
Message-ID: <87zfwjs3vs.fsf@waldekranz.com> (raw)
In-Reply-To: <20240201204940.5f5b6e85@kernel.org>
On tor, feb 01, 2024 at 20:49, Jakub Kicinski <kuba@kernel•org> wrote:
> On Tue, 30 Jan 2024 21:19:34 +0100 Tobias Waldekranz wrote:
>> Useful both in error messages and in tracepoints.
>
> Are you printing things together into one big string?
> Seems like leaving a lot of features on the table.
> trace point events can be filtered, not to mention attaching
> to them with bpftrace.
My thinking was that __entry->msg was mostly for use by the tracepoint's
printf, and that if you are using some dynamic tracer, __entry->info
points to the verbatim notification which you can use to apply arbitrary
filtering.
> There's also a built-in way to show traces how to convert numerical ids
> to strings for the basic output - __print_symbolic().
> None of that can help here?
Originally, I did use it to display the `val` argument to the
tracepoint, but the problem with that macro is that it wants the mapping
table as an inline list of tuples, and the list must _not_ include a
trailing comma. This means that SWITCHDEV_TYPE_MAPPER can't use the
trailing-comment-after-the-last-item trick, which introduced an
asymmetry with the other mappers that I did not like.
At first, I thought about adding some variant of __print_symbolic that
would take a pointer to an existing table instead. Then I realized that
I would still need some separate stringer helper to put together the
rest of the printed message from the TLV-ish layout of
switchdev_notifier_info.
At that point, it seems more reasonable to just collect all logic of
turning switchdev related structs into strings in one place - with the
added benefit that drivers could use them to log richer error messages.
next prev parent reply other threads:[~2024-02-02 7:48 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 20:19 [PATCH v2 net-next 0/5] net: switchdev: Tracepoints Tobias Waldekranz
2024-01-30 20:19 ` [PATCH v2 net-next 1/5] net: switchdev: Wrap enums in mapper macros Tobias Waldekranz
2024-01-30 20:19 ` [PATCH v2 net-next 2/5] net: switchdev: Add helpers to display switchdev objects as strings Tobias Waldekranz
2024-02-02 4:49 ` Jakub Kicinski
2024-02-02 7:48 ` Tobias Waldekranz [this message]
2024-02-02 18:34 ` Jakub Kicinski
2024-01-30 20:19 ` [PATCH v2 net-next 3/5] net: switchdev: Relay all replay messages through a central function Tobias Waldekranz
2024-01-30 20:19 ` [PATCH v2 net-next 4/5] net: switchdev: Prepare deferred notifications before enqueuing them Tobias Waldekranz
2024-01-30 20:19 ` [PATCH v2 net-next 5/5] net: switchdev: Add tracepoints Tobias Waldekranz
2024-02-02 4:44 ` [PATCH v2 net-next 0/5] net: switchdev: Tracepoints Jakub Kicinski
2024-02-02 7:21 ` Tobias Waldekranz
2024-02-02 18:32 ` Jakub Kicinski
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