netmap: silence -Wdefault-const-init-field-unsafe warning
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Authored by arichardson on Sep 16 2025, 5:32 AM.

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vmaffione
jhb

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rG2ed21f90906b: netmap: silence -Wdefault-const-init-field-unsafe warning

Summary

The netmap_ring struct starts with various const members and rencent
clang warns about leaving them uninitialized. Having them const in the
first place is highly suspicious since they are updated with various
macros but using hand-coded __DECONST(). But fixing that is a more
invasive change that I am unable to test.

.../freebsd/sys/dev/netmap/netmap_kloop.c:320:21: error: default initialization of an object of type 'struct netmap_ring' with const member leaves the object uninitialized [-Werror,-Wdefault-const-init-field-unsafe]
  320 |         struct netmap_ring shadow_ring; /* shadow copy of the netmap_ring */
      |                            ^
.../freebsd/sys/net/netmap.h:290:16: note: member 'buf_ofs' declared 'const' here
  290 |         const int64_t   buf_ofs;
      |                         ^

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rG FreeBSD src repository

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Tests Not Applicable

Event Timeline

arichardson created this revision.Sep 16 2025, 5:32 AM

Herald added a subscriber: imp. · View Herald TranscriptSep 16 2025, 5:32 AM

Harbormaster completed remote builds in B67071: Diff 162132.Sep 16 2025, 5:32 AM

arichardson requested review of this revision.Sep 16 2025, 5:32 AM

Thanks.

The fields are const because we want to prevent changes after they are initialized. Of course you need to drop the const to initialize them.
They are not meant to be updated.

This revision is now accepted and ready to land.Sep 17 2025, 9:57 PM

jhb accepted this revision.Oct 28 2025, 6:45 PM

Closed by commit rG2ed21f90906b: netmap: silence -Wdefault-const-init-field-unsafe warning (authored by arichardson). · Explain WhyDec 16 2025, 8:23 PM

This revision was automatically updated to reflect the committed changes.

arichardson added a commit: rG2ed21f90906b: netmap: silence -Wdefault-const-init-field-unsafe warning.