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Subject[RFC PATCH 00/20] Remove Mysterious Macro Intended to Obscure Weird Behaviours (mmiowb())
Date
Hi all,

This series attempts to remove explicit mmiowb() calls from driver code,
instead adding it to spin_unlock() for architectures that require it.

The infamous "PowerPC trick" was found to be flawed, so a correct but probably
slower version is made generic for architectures wishing to use it. I've ported
RISC-V over to this interface, and hooked up PowerPC to the generic
infrastructure but with their existing implementation. Other architectures that
require a definition for mmiowb() now have it unconditionally called from their
spin_unlock() code. If this is deemed to be expensive, they should be able to
do something similar to RISC-V.

I used coccinelle to remove the vast majority of the users, and the trivial
spatch invocation is included in the commit message of that patch. I've also
*build-tested* this for RISC-V, ia64, mips64, sh, powerpc64 and arm64.

This is based on a couple of other I/O-related series that I have pending:

https://lkml.org/lkml/2019/2/22/484
https://lkml.org/lkml/2019/2/22/500

so I've pushed the whole lot out on a branch for your comfort and convenience:

git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git io

Feedback welcome,

Will

Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Tony Luck <tony.luck@intel.com>

--->8

Will Deacon (20):
asm-generic/mmiowb: Add generic implementation of mmiowb() tracking
arch: Use asm-generic header for asm/mmiowb.h
mmiowb: Hook up mmiowb helpers to spinlocks and generic I/O accessors
ARM: io: Remove useless definition of mmiowb()
arm64: io: Remove useless definition of mmiowb()
x86: io: Remove useless definition of mmiowb()
nds32: io: Remove useless definition of mmiowb()
m68k: io: Remove useless definition of mmiowb()
sh: Add unconditional mmiowb() to arch_spin_unlock()
mips: Add unconditional mmiowb() to arch_spin_unlock()
ia64: Add unconditional mmiowb() to arch_spin_unlock()
powerpc: mmiowb: Hook up mmwiob() implementation to asm-generic code
riscv: mmiowb: Hook up mmwiob() implementation to asm-generic code
Documentation: Kill all references to mmiowb()
drivers: Remove useless trailing comments from mmiowb() invocations
drivers: Remove explicit invocations of mmiowb()
scsi: qla1280: Remove stale comment about mmiowb()
i40iw: Redefine i40iw_mmiowb() to do nothing
net: silan: sc92031: Remove stale comment about mmiowb()
arch: Remove dummy mmiowb() definitions from arch code

Documentation/driver-api/device-io.rst | 45 ---------
Documentation/driver-api/pci/p2pdma.rst | 4 -
Documentation/memory-barriers.txt | 103 +--------------------
arch/alpha/include/asm/Kbuild | 1 +
arch/alpha/include/asm/io.h | 2 -
arch/arc/include/asm/Kbuild | 1 +
arch/arm/include/asm/Kbuild | 1 +
arch/arm/include/asm/io.h | 2 -
arch/arm64/include/asm/Kbuild | 1 +
arch/arm64/include/asm/io.h | 2 -
arch/c6x/include/asm/Kbuild | 1 +
arch/csky/include/asm/Kbuild | 1 +
arch/h8300/include/asm/Kbuild | 1 +
arch/hexagon/include/asm/Kbuild | 1 +
arch/hexagon/include/asm/io.h | 2 -
arch/ia64/include/asm/io.h | 4 -
arch/ia64/include/asm/mmiowb.h | 12 +++
arch/ia64/include/asm/spinlock.h | 2 +
arch/m68k/include/asm/Kbuild | 1 +
arch/m68k/include/asm/io_mm.h | 2 -
arch/microblaze/include/asm/Kbuild | 1 +
arch/mips/include/asm/io.h | 3 -
arch/mips/include/asm/mmiowb.h | 11 +++
arch/mips/include/asm/spinlock.h | 15 +++
arch/nds32/include/asm/Kbuild | 1 +
arch/nds32/include/asm/io.h | 2 -
arch/nios2/include/asm/Kbuild | 1 +
arch/openrisc/include/asm/Kbuild | 1 +
arch/parisc/include/asm/Kbuild | 1 +
arch/parisc/include/asm/io.h | 2 -
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/io.h | 33 +------
arch/powerpc/include/asm/mmiowb.h | 41 ++++++++
arch/powerpc/include/asm/spinlock.h | 17 ----
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/io.h | 15 +--
arch/riscv/include/asm/mmiowb.h | 14 +++
arch/s390/include/asm/Kbuild | 1 +
arch/sh/include/asm/io.h | 3 -
arch/sh/include/asm/mmiowb.h | 12 +++
arch/sh/include/asm/spinlock-llsc.h | 2 +
arch/sparc/include/asm/Kbuild | 1 +
arch/sparc/include/asm/io_64.h | 2 -
arch/um/include/asm/Kbuild | 1 +
arch/unicore32/include/asm/Kbuild | 1 +
arch/x86/include/asm/io.h | 2 -
arch/xtensa/include/asm/Kbuild | 1 +
drivers/crypto/cavium/nitrox/nitrox_reqmgr.c | 4 -
drivers/dma/txx9dmac.c | 3 -
drivers/firewire/ohci.c | 1 -
drivers/gpu/drm/i915/intel_hdmi.c | 10 --
drivers/ide/tx4939ide.c | 2 -
drivers/infiniband/hw/hfi1/chip.c | 3 -
drivers/infiniband/hw/hfi1/pio.c | 1 -
drivers/infiniband/hw/hns/hns_roce_hw_v1.c | 2 -
drivers/infiniband/hw/i40iw/i40iw_osdep.h | 2 +-
drivers/infiniband/hw/mlx4/qp.c | 6 --
drivers/infiniband/hw/mlx5/qp.c | 1 -
drivers/infiniband/hw/mthca/mthca_cmd.c | 6 --
drivers/infiniband/hw/mthca/mthca_cq.c | 5 -
drivers/infiniband/hw/mthca/mthca_qp.c | 17 ----
drivers/infiniband/hw/mthca/mthca_srq.c | 6 --
drivers/infiniband/hw/qedr/verbs.c | 12 ---
drivers/infiniband/hw/qib/qib_iba6120.c | 4 -
drivers/infiniband/hw/qib/qib_iba7220.c | 3 -
drivers/infiniband/hw/qib/qib_iba7322.c | 3 -
drivers/infiniband/hw/qib/qib_sd7220.c | 4 -
drivers/media/pci/dt3155/dt3155.c | 8 --
drivers/memstick/host/jmb38x_ms.c | 4 -
drivers/misc/ioc4.c | 2 -
drivers/misc/mei/hw-me.c | 3 -
drivers/misc/tifm_7xx1.c | 1 -
drivers/mmc/host/alcor.c | 1 -
drivers/mmc/host/sdhci.c | 13 ---
drivers/mmc/host/tifm_sd.c | 3 -
drivers/mmc/host/via-sdmmc.c | 10 --
drivers/mtd/nand/raw/r852.c | 2 -
drivers/mtd/nand/raw/txx9ndfmc.c | 1 -
drivers/net/ethernet/aeroflex/greth.c | 1 -
drivers/net/ethernet/alacritech/slicoss.c | 4 -
drivers/net/ethernet/amazon/ena/ena_com.c | 1 -
drivers/net/ethernet/atheros/atlx/atl1.c | 1 -
drivers/net/ethernet/atheros/atlx/atl2.c | 1 -
drivers/net/ethernet/broadcom/bnx2.c | 4 -
drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 2 -
drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h | 4 -
.../net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c | 1 -
drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c | 29 ------
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sp.c | 1 -
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c | 2 -
drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c | 4 -
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 3 -
drivers/net/ethernet/broadcom/tg3.c | 6 --
.../net/ethernet/cavium/liquidio/cn66xx_device.c | 10 --
.../net/ethernet/cavium/liquidio/octeon_device.c | 1 -
drivers/net/ethernet/cavium/liquidio/octeon_droq.c | 4 -
.../net/ethernet/cavium/liquidio/request_manager.c | 1 -
drivers/net/ethernet/intel/e1000/e1000_main.c | 5 -
drivers/net/ethernet/intel/e1000e/netdev.c | 7 --
drivers/net/ethernet/intel/fm10k/fm10k_iov.c | 2 -
drivers/net/ethernet/intel/fm10k/fm10k_main.c | 5 -
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 5 -
drivers/net/ethernet/intel/iavf/iavf_txrx.c | 5 -
drivers/net/ethernet/intel/ice/ice_txrx.c | 5 -
drivers/net/ethernet/intel/igb/igb_main.c | 5 -
drivers/net/ethernet/intel/igbvf/netdev.c | 4 -
drivers/net/ethernet/intel/igc/igc_main.c | 5 -
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 5 -
drivers/net/ethernet/marvell/sky2.c | 4 -
drivers/net/ethernet/mellanox/mlx4/catas.c | 4 -
drivers/net/ethernet/mellanox/mlx4/cmd.c | 13 ---
drivers/net/ethernet/mellanox/mlx5/core/cmd.c | 1 -
drivers/net/ethernet/myricom/myri10ge/myri10ge.c | 2 -
drivers/net/ethernet/neterion/s2io.c | 2 -
drivers/net/ethernet/neterion/vxge/vxge-main.c | 5 -
drivers/net/ethernet/neterion/vxge/vxge-traffic.c | 4 -
drivers/net/ethernet/qlogic/qed/qed_int.c | 13 ---
drivers/net/ethernet/qlogic/qed/qed_spq.c | 3 -
drivers/net/ethernet/qlogic/qede/qede_ethtool.c | 8 --
drivers/net/ethernet/qlogic/qede/qede_fp.c | 8 --
drivers/net/ethernet/qlogic/qla3xxx.c | 1 -
drivers/net/ethernet/qlogic/qlge/qlge.h | 1 -
drivers/net/ethernet/qlogic/qlge/qlge_main.c | 1 -
drivers/net/ethernet/realtek/r8169.c | 5 -
drivers/net/ethernet/renesas/ravb_main.c | 9 --
drivers/net/ethernet/renesas/ravb_ptp.c | 3 -
drivers/net/ethernet/renesas/sh_eth.c | 1 -
drivers/net/ethernet/sfc/falcon/io.h | 2 -
drivers/net/ethernet/sfc/io.h | 2 -
drivers/net/ethernet/silan/sc92031.c | 15 ---
drivers/net/ethernet/via/via-rhine.c | 3 -
drivers/net/ethernet/wiznet/w5100.c | 6 --
drivers/net/ethernet/wiznet/w5300.c | 15 ---
drivers/net/wireless/ath/ath5k/base.c | 4 -
drivers/net/wireless/ath/ath5k/mac80211-ops.c | 2 -
drivers/net/wireless/broadcom/b43/main.c | 7 --
drivers/net/wireless/broadcom/b43/sysfs.c | 1 -
drivers/net/wireless/broadcom/b43legacy/ilt.c | 2 -
drivers/net/wireless/broadcom/b43legacy/main.c | 20 ----
drivers/net/wireless/broadcom/b43legacy/phy.c | 1 -
drivers/net/wireless/broadcom/b43legacy/pio.h | 1 -
drivers/net/wireless/broadcom/b43legacy/radio.c | 4 -
drivers/net/wireless/broadcom/b43legacy/sysfs.c | 1 -
drivers/net/wireless/intel/iwlegacy/common.h | 7 --
drivers/net/wireless/intel/iwlwifi/pcie/trans.c | 1 -
drivers/ntb/hw/idt/ntb_hw_idt.c | 7 --
drivers/ntb/test/ntb_perf.c | 3 -
drivers/scsi/bfa/bfa.h | 3 +-
drivers/scsi/bfa/bfa_hw_cb.c | 2 -
drivers/scsi/bfa/bfa_hw_ct.c | 2 -
drivers/scsi/bnx2fc/bnx2fc_hwi.c | 2 -
drivers/scsi/bnx2i/bnx2i_hwi.c | 3 -
drivers/scsi/megaraid/megaraid_sas_base.c | 1 -
drivers/scsi/megaraid/megaraid_sas_fusion.c | 1 -
drivers/scsi/mpt3sas/mpt3sas_base.c | 1 -
drivers/scsi/qedf/qedf_io.c | 1 -
drivers/scsi/qedi/qedi_fw.c | 1 -
drivers/scsi/qla1280.c | 15 ---
drivers/ssb/pci.c | 1 -
drivers/ssb/pcmcia.c | 4 -
drivers/staging/comedi/drivers/mite.c | 3 -
drivers/staging/comedi/drivers/ni_660x.c | 2 -
drivers/staging/comedi/drivers/ni_mio_common.c | 1 -
drivers/staging/comedi/drivers/ni_pcidio.c | 2 -
drivers/staging/comedi/drivers/ni_tio.c | 1 -
drivers/staging/comedi/drivers/s626.c | 2 -
drivers/tty/serial/men_z135_uart.c | 1 -
drivers/tty/serial/serial_txx9.c | 1 -
drivers/usb/early/xhci-dbc.c | 4 -
drivers/usb/host/xhci-dbgcap.c | 2 -
include/asm-generic/io.h | 3 +-
include/asm-generic/mmiowb.h | 60 ++++++++++++
include/linux/qed/qed_if.h | 2 -
include/linux/spinlock.h | 11 ++-
kernel/Kconfig.locks | 3 +
kernel/locking/spinlock.c | 5 +
kernel/locking/spinlock_debug.c | 6 +-
sound/soc/txx9/txx9aclc-ac97.c | 1 -
178 files changed, 226 insertions(+), 764 deletions(-)
create mode 100644 arch/ia64/include/asm/mmiowb.h
create mode 100644 arch/mips/include/asm/mmiowb.h
create mode 100644 arch/powerpc/include/asm/mmiowb.h
create mode 100644 arch/riscv/include/asm/mmiowb.h
create mode 100644 arch/sh/include/asm/mmiowb.h
create mode 100644 include/asm-generic/mmiowb.h

--
2.11.0

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