Hi!
Some NICs (e.g. bnxt) change their RSS indirection table size based on
the queue count, because the hardware table is a shared resource. The
ethtool core locks ctx->indir_size at context creation, so drivers
have to reject channel changes when RSS contexts exist.
This series adds resize helpers and wires them up in bnxt.
Patch 1 adds core helpers:
ethtool_rxfh_can_resize() - read-only validation
ethtool_rxfh_resize() - fold/unfold a raw table in place
ethtool_rxfh_ctxs_can_resize() - validate all non-default contexts
ethtool_rxfh_ctxs_resize() - resize all non-default contexts,
with locking and RSS_NTF notifications
Patch 2 uses them in bnxt_set_channels(). Validation runs before
bnxt_close_nic(); actual resize is deferred until after. RSS table
size only changes on P5 chips with older firmware.
Patch 3 adds HW tests in rss_drv.py (devices without dynamic table
sizing are skipped):
resize_periodic - fold/unfold with a non-default [3,2,1,0]xN
pattern, verifying exact content preservation (main + ctx)
resize_nonperiodic_reject - non-periodic table blocks channel
reduction, with an extra periodic context to exercise
multi-context validation (main + ctx)
resize_nonperiodic_no_corruption - failed resize leaves table
contents and channel count unchanged (main + ctx)
Running the tests:
# On real hardware
sudo NETIF=eth0 ./rss_drv.py
Changes v1 -> v2:
- Dropped netdevsim support and netdevsim selftest (Jakub)
- Split ethtool_rxfh_contexts_resize_all() into separate validate
(ethtool_rxfh_ctxs_can_resize) and apply (ethtool_rxfh_ctxs_resize)
so drivers can validate before closing the device (Jakub)
- Shortened helper names (Jakub)
- Replaced scoped_guard(mutex) with explicit mutex_lock/unlock
(Jakub)
- Removed defensive zero-size check, bare expressions instead of != 0
comparisons, ! instead of == 0 (Jakub)
- In bnxt, moved bnxt_check_rings() before RSS validation and
deferred actual resize to after bnxt_close_nic() (Jakub, Michael)
- Added comment that RSS table size only changes on P5 chips with
older firmware (Michael)
- Use non-default [3,2,1,0]xN pattern set via netlink to distinguish
correct fold from driver resetting to defaults (Jakub)
- Check exact indirection table pattern, not just set(indir) (Jakub)
- Use ksft_raises() instead of try/except/else (Jakub)
- Removed queue_count=8 from NetDrvEnv (Jakub)
- Added ksft_variants to resize_nonperiodic_reject for ctx coverage
- Added extra periodic context in reject test for multi-context
validation coverage
- Added resize_nonperiodic_no_corruption test
Open items:
- No user-controlled minimum table size yet. The plan is to record
the user-provided indirection table length in the context (e.g.
ctx->user_indir_size) and use it as a floor when folding: reject if
new_size < user_indir_size. This way the user's original table size
serves as an implicit minimum, preventing the driver from shrinking
below what the user intended. Left for a follow-up.
Björn Töpel (3):
ethtool: Add RSS indirection table resize helpers
bnxt_en: Resize RSS contexts on channel count change
selftests: rss_drv: Add RSS indirection table resize tests
.../net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 36 +++-
include/linux/ethtool.h | 4 +
net/ethtool/common.c | 146 ++++++++++++++++
.../selftests/drivers/net/hw/rss_drv.py | 163 +++++++++++++++++-
4 files changed, 338 insertions(+), 11 deletions(-)
base-commit: ed0abfe93fd135dac223e87a3c945017b1fa8bfc
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2.53.0
