This RFC proposes a solution to keep protecting the fpga manager against the unloading of the low-level control modules while addressing the limitations of the current implementation. Currently, the code assumes that the low-level module registers a platform driver for the parent device that is later used by the fpga manager (through the parent device's driver pointer) to take the low-level module's refcount. This proposal removes this limitation by adding a module owner field to the fpga_manager_ops struct. Low-level control modules can statically set the owner field to THIS_MODULE, and the fpga manager can later use it to take the low-level module's refcount. For more context, please refer to these threads: https://lore.kernel.org/linux-fpga/ZS6hhlvjUcqyv8zL@yilunxu-OptiPlex-7050 https://lore.kernel.org/linux-fpga/ZT9qENE9fE3Z0KCW@yilunxu-OptiPlex-7050 v3: - Improved locking using Yilun's proposal v2: - Fixed protection against races during module removal Marco Pagani (2): fpga: add an owner field and use it to take the low-level module's refcount fpga: set owner of fpga_manager_ops for existing low-level modules drivers/fpga/altera-cvp.c | 1 + drivers/fpga/altera-pr-ip-core.c | 1 + drivers/fpga/altera-ps-spi.c | 1 + drivers/fpga/dfl-fme-mgr.c | 1 + drivers/fpga/fpga-mgr.c | 50 ++++++++++++++++++--------- drivers/fpga/ice40-spi.c | 1 + drivers/fpga/lattice-sysconfig.c | 1 + drivers/fpga/machxo2-spi.c | 1 + drivers/fpga/microchip-spi.c | 1 + drivers/fpga/socfpga-a10.c | 1 + drivers/fpga/socfpga.c | 1 + drivers/fpga/stratix10-soc.c | 1 + drivers/fpga/tests/fpga-mgr-test.c | 1 + drivers/fpga/tests/fpga-region-test.c | 1 + drivers/fpga/ts73xx-fpga.c | 1 + drivers/fpga/versal-fpga.c | 1 + drivers/fpga/xilinx-spi.c | 1 + drivers/fpga/zynq-fpga.c | 1 + drivers/fpga/zynqmp-fpga.c | 1 + include/linux/fpga/fpga-mgr.h | 4 +++ 20 files changed, 56 insertions(+), 16 deletions(-) base-commit: ceb6a6f023fd3e8b07761ed900352ef574010bcb -- 2.43.0
