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Pinning trace error is misleading in ebpf_pinning_table_find function #2897

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shpalani opened this issue Sep 23, 2023 · 0 comments · Fixed by #2954
Closed

Pinning trace error is misleading in ebpf_pinning_table_find function #2897

shpalani opened this issue Sep 23, 2023 · 0 comments · Fixed by #2954
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@shpalani
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cleanup Affects API usability or code maintainability but not correctness or applicability triaged Discussed in a triage meeting
Milestone
2311

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@shpalani
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Describe the bug

Debuggability: Pinning error trace is misleading in debugging.

It is expected to have a key not found when the map is newly created and pinning is not done.

Trace:
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_create_map returned success
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_get_pinned_object
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_pinning_table_find
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_pinning_table_find returned error,19
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_get_pinned_object returned error,19
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_create_map
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_map_create
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]_create_object_hash_map
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.935 [EbpfForWindowsProvider]_create_object_hash_map returned success
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.935 [EbpfForWindowsProvider]eBPF object initialized,0xFFFFB589858AAF30,1

where 19 is KEY_NOT_FOUND.

OS information

Windows 10 and above.

Steps taken to reproduce bug

  1. Enable tracing, and load ebpf program with maps.
    logman create trace "xdp_trace" -o C:\Temp\xdp_trace.etl -f bincirc -max 1024 -ets
    logman update trace "xdp_trace" -p "{394f321c-5cf4-404c-aa34-4df1428a7f9c}" 0xffffffffffffffff 0xff -ets
    logman update trace "xdp_trace" -p "{f2f2ca01-ad02-4a07-9e90-95a2334f3692}" 0xffffffffffffffff 0xff -ets
    logman update trace "xdp_trace" -p "{00e7ee66-5b24-5c41-22cb-af98f63e2f90}" 0xffffffffffffffff 0xff -ets
    logman stop "xdp_trace" -ets

netsh trace convert C:\Temp\xdp_trace.etl

xdp_trace_2.txt

Expected behavior

The proposal agreed upon internal discussion:

  1. Remove the return statement from ebpf_pinning_table_find()
  • EBPF_RETURN_RESULT(return_value);
  • return the return_value.
  1. Add the trace in the callers of this ebpf_pinning_table_find(), if it is a valid error.

Actual outcome

Prints error of 19 (KEY_NOT_FOUND)

[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_create_map returned success
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_get_pinned_object
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_pinning_table_find
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_pinning_table_find returned error,19
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_get_pinned_object returned error,19
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_core_create_map
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]ebpf_map_create
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.933 [EbpfForWindowsProvider]_create_object_hash_map
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.935 [EbpfForWindowsProvider]_create_object_hash_map returned success
[39]1624.193C::‎2023‎-‎09‎-‎21 15:06:26.935 [EbpfForWindowsProvider]eBPF object initialized,0xFFFFB589858AAF30,1

Additional details

No response
@shpalani shpalani added the bug Something isn't working label Sep 23, 2023
@dahavey dahavey added the triaged Discussed in a triage meeting label Sep 25, 2023
@dahavey dahavey added cleanup Affects API usability or code maintainability but not correctness or applicability and removed bug Something isn't working labels Sep 25, 2023
@dahavey dahavey added this to the 2310 milestone Sep 25, 2023
@shpalani shpalani linked a pull request Oct 6, 2023 that will close this issue
Change trace in ebpf_pinning_table_find #2954
Merged
@shankarseal shankarseal modified the milestones: 2310, 2311 Oct 23, 2023
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cleanup Affects API usability or code maintainability but not correctness or applicability triaged Discussed in a triage meeting
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Milestone
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Change trace in ebpf_pinning_table_find shpalani/ebpf-for-windows
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@shpalani @dahavey @shankarseal