This is an implementation of the idea provided by Jakub here
https://lore.kernel.org/netdev/[email protected]/
ndo_set_rx_mode is problematic because it cannot sleep.
To address this, this series proposes dividing the concept of setting
rx_mode into 2 stages: snapshot and deferred I/O. To achieve this, we
change the semantics of set_rx_mode and add a new ndo write_rx_mode.
The new set_rx_mode will be responsible for customizing the rx_mode
snapshot which will be used by write_rx_mode to update the hardware
This refactor has the secondary benefit of stopping set rx_mode
requests from building up as only the most recent request (before the
work has gotten a chance to run) will be confirmed/executed.
In brief, the new flow will look something like:
set_rx_mode():
ndo_set_rx_mode();
prepare_rx_mode();
write_rx_mode():
use_snapshot();
ndo_write_rx_mode();
write_rx_mode() is called from a work item and doesn't hold the
netif_addr_lock spin lock during ndo_write_rx_mode() making it sleepable
in that section.
This model should work correctly if the following conditions hold:
1. write_rx_mode should use the rx_mode set by the most recent
call to prepare_rx_mode() before its execution.
2. If a make_snapshot_ready call happens during execution of write_rx_mode,
write_rx_mode() should be rescheduled.
3. All calls to modify rx_mode should pass through the prepare_rx_mode +
schedule write_rx_mode() execution flow. netif_schedule_rx_mode_work()
has been implemented in core for this purpose.
1 and 2 are implemented in core
Drivers need to ensure 3 using netif_schedule_rx_mode_work()
To use this model, a driver needs to implement the
ndo_write_rx_mode callback, change the set_rx_mode callback
appropriately and replace all calls to modify rx mode with
netif_schedule_rx_mode_work()
Signed-off-by: I Viswanath <[email protected]>
---
v1:
Link:
https://lore.kernel.org/netdev/[email protected]/
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/[email protected]/
v3:
- Added RFT tag
- Corrected mangled patch
Link:
https://lore.kernel.org/netdev/[email protected]/
v4:
- Completely reworked the snapshot mechanism as per v3 comments
- Implemented the callback for virtio-net instead of 8139cp driver
- Removed RFC tag
Link:
https://lore.kernel.org/netdev/[email protected]/
v5:
- Fix broken code and titles
- Remove RFT tag
Link:
https://lore.kernel.org/netdev/[email protected]/
v6:
- Added struct netif_deferred_work_cleanup and members needs_deferred_cleanup
and deferred_work_cleanup in net_device
- Moved out ctrl bits from netif_rx_mode_config to netif_rx_mode_work_ctx
Link:
https://lore.kernel.org/netdev/[email protected]/
v7:
- Improved function, enum and struct names
Link:
https://lore.kernel.org/netdev/[email protected]/
v8:
- Implemented the callback for drivers e1000, 8139cp, vmxnet3 and pcnet32
- Moved the rx_mode config set calls (for prom and allmulti) in prepare_rx_mode
to the ndo_set_rx_mode callback for consistency
- Improved commit messages
I Viswanath (6):
net: refactor set_rx_mode into snapshot and deferred I/O
virtio-net: Implement ndo_write_rx_mode callback
e1000: Implement ndo_write_rx_mode callback
8139cp: Implement ndo_write_rx_mode callback
vmxnet3: Implement ndo_write_rx_mode callback
pcnet32: Implement ndo_write_rx_mode callback
drivers/net/ethernet/amd/pcnet32.c | 57 +++-
drivers/net/ethernet/intel/e1000/e1000_main.c | 59 ++--
drivers/net/ethernet/realtek/8139cp.c | 33 ++-
drivers/net/virtio_net.c | 61 ++--
drivers/net/vmxnet3/vmxnet3_drv.c | 38 ++-
include/linux/netdevice.h | 112 +++++++-
net/core/dev.c | 265 +++++++++++++++++-
7 files changed, 522 insertions(+), 103 deletions(-)
--
2.47.3
