[patch 00/35] net: in_interrupt() cleanup and fixes

[Thomas Gleixner]

Folks,

in the discussion about preempt count consistency accross kernel configurations:

  https://lore.kernel.org/r/20200914204209.256266093@xxxxxxxxxxxxx/

Linus clearly requested that code in drivers and libraries which changes
behaviour based on execution context should either be split up so that
e.g. task context invocations and BH invocations have different interfaces
or if that's not possible the context information has to be provided by the
caller which knows in which context it is executing.

This includes conditional locking, allocation mode (GFP_*) decisions and
avoidance of code paths which might sleep.

In the long run, usage of 'preemptible, in_*irq etc.' should be banned from
driver code completely.

Our team started to dig through drivers and this it the first batch of
cleanups in drivers/net/. It's not yet complete, so expect further patches
in the next days.

The series contains:

    - A couple of bug fixes

    - Removal of the bitrotting CAIF SPI driver which has never had a
      matching driver providing the necessary platform device support.

    - Removal of WARN/BUG(in_interrupt()) en masse as most of them are
      incomplete because they won't detect other non-preemptible
      context. All of the functions which have these WARN/BUG invoke core
      code functions which can sleep. These have plenty of checks to catch
      _all_ invalid contexts. So it's pointless to have incomplete WARN/BUG
      in the drivers.

      If a driver wants to have such a check for paranoia reasons, then
      e.g. lockdep_assert_preemtion_enabled() is the right mechanism to
      chose because lockdep guarantees to catch all invalid contexts
      independent of kernel configuration while e.g. preemptible() does
      not.

    - Conversion of in_interrupt() checks to use either different functions
      or to hand the context information in from the caller.

    - For some drivers handing the context into functions which decided
      between netif_rx() and netif_rx_ni() turned out to be impossible due
      to lack of driver knowledge and convoluted code pathes with multiple
      indirections. For those a core code function netif_rx_any_context()
      is provided which contains an in_interrupt() check as a stop
      gap. This allows to make progess on the driver side cleanup and
      the function should go away once the driver wizards have fixed it
      up proper.

    - Simplifcation and cleanups in various places where code pointlessly
      contains in_interrupt() conditionals which are mostly leftovers from
      calling conventions in older kernels and have never been cleaned up.

      Along with removing if from the horrible DBG_FOO() macro mess which
      probably should be removed completely as the kernel today provides
      way more sensible mechanisms to do function tracing and similar.

    - A few other cleanups which were obvious when chasing the
      in_interrupt() usage.

The pile is also available from:

    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git softirq

The diffstat summary is:

 86 files changed, 300 insertions(+), 2233 deletions(-)

which is biased by the CAIF SPI removal. Without that it is:

 79 files changed, 300 insertions(+), 697 deletions(-)

Thanks,

	tglx
---
 Documentation/networking/caif/spi_porting.rst                   |  229 --
 b/Documentation/networking/caif/index.rst                       |    1 
 b/drivers/net/caif/Kconfig                                      |   19 
 b/drivers/net/caif/Makefile                                     |    4 
 b/drivers/net/caif/caif_hsi.c                                   |   19 
 b/drivers/net/ethernet/amd/sun3lance.c                          |   11 
 b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c               |    1 
 b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c               |    2 
 b/drivers/net/ethernet/atheros/atlx/atl2.c                      |    1 
 b/drivers/net/ethernet/chelsio/cxgb3/adapter.h                  |    1 
 b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c               |    2 
 b/drivers/net/ethernet/chelsio/cxgb3/sge.c                      |   44 
 b/drivers/net/ethernet/chelsio/cxgb4/sge.c                      |    3 
 b/drivers/net/ethernet/cisco/enic/enic.h                        |    1 
 b/drivers/net/ethernet/cisco/enic/enic_api.c                    |    6 
 b/drivers/net/ethernet/cisco/enic/enic_main.c                   |   27 
 b/drivers/net/ethernet/freescale/fec_mpc52xx.c                  |   10 
 b/drivers/net/ethernet/intel/e100.c                             |    4 
 b/drivers/net/ethernet/intel/e1000/e1000_main.c                 |    1 
 b/drivers/net/ethernet/intel/fm10k/fm10k_pci.c                  |    2 
 b/drivers/net/ethernet/intel/i40e/i40e_main.c                   |    4 
 b/drivers/net/ethernet/intel/ice/ice_main.c                     |    1 
 b/drivers/net/ethernet/intel/igb/igb_main.c                     |    1 
 b/drivers/net/ethernet/intel/igc/igc_main.c                     |    1 
 b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c                 |    1 
 b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c             |    2 
 b/drivers/net/ethernet/natsemi/sonic.c                          |   24 
 b/drivers/net/ethernet/natsemi/sonic.h                          |    2 
 b/drivers/net/ethernet/neterion/vxge/vxge-config.c              |    9 
 b/drivers/net/ethernet/neterion/vxge/vxge-config.h              |    7 
 b/drivers/net/ethernet/pensando/ionic/ionic_dev.c               |    2 
 b/drivers/net/ethernet/pensando/ionic/ionic_lif.c               |   43 
 b/drivers/net/ethernet/pensando/ionic/ionic_lif.h               |    2 
 b/drivers/net/ethernet/pensando/ionic/ionic_main.c              |    4 
 b/drivers/net/ethernet/sfc/ef10.c                               |   18 
 b/drivers/net/ethernet/sfc/ef100_nic.c                          |    3 
 b/drivers/net/ethernet/sfc/efx_common.c                         |    6 
 b/drivers/net/ethernet/sfc/ethtool_common.c                     |    2 
 b/drivers/net/ethernet/sfc/net_driver.h                         |    3 
 b/drivers/net/ethernet/sfc/siena.c                              |    3 
 b/drivers/net/ethernet/sun/sunbmac.c                            |   18 
 b/drivers/net/phy/mdio_bus.c                                    |   15 
 b/drivers/net/usb/kaweth.c                                      |  261 --
 b/drivers/net/usb/net1080.c                                     |    1 
 b/drivers/net/wan/lmc/lmc_debug.c                               |   18 
 b/drivers/net/wan/lmc/lmc_debug.h                               |    1 
 b/drivers/net/wan/lmc/lmc_main.c                                |  105 -
 b/drivers/net/wan/lmc/lmc_media.c                               |    4 
 b/drivers/net/wan/lmc/lmc_proto.c                               |   16 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c     |    4 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/bus.h        |    5 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c       |   20 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.c       |    8 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.h       |    7 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c     |    2 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c       |   12 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.h       |    2 
 b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/usb.c        |    2 
 b/drivers/net/wireless/intel/ipw2x00/ipw2100.c                  |    3 
 b/drivers/net/wireless/intel/ipw2x00/ipw2200.h                  |    6 
 b/drivers/net/wireless/intel/ipw2x00/libipw.h                   |    3 
 b/drivers/net/wireless/intel/iwlegacy/common.h                  |    4 
 b/drivers/net/wireless/intel/iwlwifi/iwl-debug.c                |    5 
 b/drivers/net/wireless/intel/iwlwifi/iwl-devtrace-msg.h         |    6 
 b/drivers/net/wireless/intersil/hostap/hostap_hw.c              |   12 
 b/drivers/net/wireless/marvell/libertas/defs.h                  |    3 
 b/drivers/net/wireless/marvell/libertas/rx.c                    |   11 
 b/drivers/net/wireless/marvell/libertas_tf/deb_defs.h           |    3 
 b/drivers/net/wireless/marvell/mwifiex/uap_txrx.c               |    6 
 b/drivers/net/wireless/marvell/mwifiex/util.c                   |    6 
 b/drivers/net/wireless/realtek/rtlwifi/base.c                   |   47 
 b/drivers/net/wireless/realtek/rtlwifi/base.h                   |    3 
 b/drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtcoutsrc.c |   12 
 b/drivers/net/wireless/realtek/rtlwifi/core.c                   |    6 
 b/drivers/net/wireless/realtek/rtlwifi/debug.c                  |   20 
 b/drivers/net/wireless/realtek/rtlwifi/debug.h                  |    6 
 b/drivers/net/wireless/realtek/rtlwifi/pci.c                    |    4 
 b/drivers/net/wireless/realtek/rtlwifi/ps.c                     |   27 
 b/drivers/net/wireless/realtek/rtlwifi/ps.h                     |   10 
 b/drivers/net/wireless/realtek/rtlwifi/wifi.h                   |    3 
 b/drivers/net/wireless/zydas/zd1211rw/zd_usb.c                  |    1 
 b/include/linux/netdevice.h                                     |    1 
 b/net/core/dev.c                                                |   15 
 drivers/net/caif/caif_spi.c                                     |  874 ----------
 drivers/net/caif/caif_spi_slave.c                               |  254 --
 include/net/caif/caif_spi.h                                     |  155 -
 86 files changed, 300 insertions(+), 2233 deletions(-)