Re: [PATCH bpf V7 1/7] selftests/bpf: xdp_hw_metadata default disable bpf_printk

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On 12/04/2023 00.42, Stanislav Fomichev wrote:
On Sat, Apr 8, 2023 at 12:24 PM Jesper Dangaard Brouer
<brouer@xxxxxxxxxx> wrote:

The tool xdp_hw_metadata can be used by driver developers
implementing XDP-hints kfuncs.  The tool transfers the
XDP-hints via metadata information to an AF_XDP userspace
process. When everything works the bpf_printk calls are
unncesssary.  Thus, disable bpf_printk by default, but
make it easy to reenable for driver developers to use
when debugging their driver implementation.

This also converts bpf_printk "forwarding UDP:9091 to AF_XDP"
into a code comment.  The bpf_printk's that are important
to the driver developers is when bpf_xdp_adjust_meta fails.
The likely mistake from driver developers is expected to
be that they didn't implement XDP metadata adjust support.

Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
---
  .../testing/selftests/bpf/progs/xdp_hw_metadata.c  |   16 ++++++++++++++--
  1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
index 4c55b4d79d3d..980eb60d8e5b 100644
--- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
+++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
@@ -5,6 +5,19 @@
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_endian.h>

+/* Per default below bpf_printk() calls are disabled.  Can be
+ * reenabled manually for convenience by XDP-hints driver developer,
+ * when troublshooting the drivers kfuncs implementation details.
+ *
+ * Remember BPF-prog bpf_printk info output can be access via:
+ *  /sys/kernel/debug/tracing/trace_pipe
+ */
+//#define DEBUG        1
+#ifndef DEBUG
+#undef  bpf_printk
+#define bpf_printk(fmt, ...) ({})
+#endif

Are you planning to eventually do somethike similar to what I've
mentioned in [0]? If not, should I try to send a patch?

See next patch:
 - [PATCH bpf V7 2/7] selftests/bpf: Add counters to xdp_hw_metadata

where I add these counters :-)


0: https://lore.kernel.org/netdev/CAKH8qBupRYEg+SPMTMb4h532GESG7P1QdaFJ-+zrbARVN9xrdA@xxxxxxxxxxxxxx/





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