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

in the discussion about preempt count consistency accross kernel configurations:

https://lore.kernel.org/r/20200914204209.256266093@linutronix.de/

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(-)
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