This is an implementation of the idea provided by Jakub here
https://lore.kernel.org/netdev/20250923163727.5e97abdb@kernel.org/
ndo_set_rx_mode is problematic because it cannot sleep.
To address this, this series proposes dividing existing set_rx_mode
implementations into set_rx_mode and write_rx_config
The new set_rx_mode will be responsible for updating the rx_config
snapshot which will be used by ndo_write_rx_config to update the hardware
In brief, The callback implementations should look something like:
set_rx_mode():
prepare_rx_config();
update_snapshot();
write_rx_config():
read_snapshot();
do_io();
write_rx_config() is called from a work item making it sleepable
during the do_io() section.
This model should work correctly if the following conditions hold:
1. write_rx_config should use the rx_config set by the most recent
call to set_rx_mode before its execution.
2. If a set_rx_mode call happens during execution of write_rx_config,
write_rx_config should be rescheduled.
3. All calls to modify rx_mode should pass through the set_rx_mode +
schedule write_rx_config execution flow.
1 and 2 are guaranteed because of the properties of work queues
Drivers need to ensure 3
ndo_write_rx_config has been implemented for 8139cp driver as proof of
concept
To use this model, a driver needs to implement the
ndo_write_rx_config callback, have a member rx_config in
the priv struct and replace all calls to set rx mode with
schedule_and_set_rx_mode();
---
v1:
Link: https://lore.kernel.org/netdev/20251020134857.5820-1-viswanathiyyappan@gmail.com/
v2:
- Exported set_and_schedule_rx_config as a symbol for use in modules
- Fixed incorrect cleanup for the case of rx_work alloc failing in alloc_netdev_mqs
- Removed the locked version (cp_set_rx_mode) and renamed __cp_set_rx_mode to cp_set_rx_mode
Link: https://lore.kernel.org/netdev/20251026175445.1519537-1-viswanathiyyappan@gmail.com/
v3:
- Added RFT tag
- Corrected mangled patch
I Viswanath (2):
net: Add ndo_write_rx_config and helper structs and functions:
net: ethernet: Implement ndo_write_rx_config callback for the 8139cp
driver
drivers/net/ethernet/realtek/8139cp.c | 78 ++++++++++++++++-----------
include/linux/netdevice.h | 38 ++++++++++++-
net/core/dev.c | 53 ++++++++++++++++--
3 files changed, 131 insertions(+), 38 deletions(-)
--
2.34.1