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Revision c269a24ce057abfc31130960e96ab197ef6ab196 authored by Jakub Kicinski on 06 January 2021, 18:40:06 UTC, committed by Jakub Kicinski on 09 January 2021, 03:27:41 UTC 
net: make free_netdev() more lenient with unregistering devices
 
There are two flavors of handling netdev registration:
 - ones called without holding rtnl_lock: register_netdev() and
   unregister_netdev(); and
 - those called with rtnl_lock held: register_netdevice() and
   unregister_netdevice().

While the semantics of the former are pretty clear, the same can't
be said about the latter. The netdev_todo mechanism is utilized to
perform some of the device unregistering tasks and it hooks into
rtnl_unlock() so the locked variants can't actually finish the work.
In general free_netdev() does not mix well with locked calls. Most
drivers operating under rtnl_lock set dev->needs_free_netdev to true
and expect core to make the free_netdev() call some time later.

The part where this becomes most problematic is error paths. There is
no way to unwind the state cleanly after a call to register_netdevice(),
since unreg can't be performed fully without dropping locks.

Make free_netdev() more lenient, and defer the freeing if device
is being unregistered. This allows error paths to simply call
free_netdev() both after register_netdevice() failed, and after
a call to unregister_netdevice() but before dropping rtnl_lock.

Simplify the error paths which are currently doing gymnastics
around free_netdev() handling.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 parent 2b446e6
Raw File
Makefile 
# SPDX-License-Identifier: GPL-2.0
#
# Makefile for the kernel block layer
#

obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-sysfs.o \
			blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
			blk-exec.o blk-merge.o blk-timeout.o \
			blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \
			blk-mq-sysfs.o blk-mq-cpumap.o blk-mq-sched.o ioctl.o \
			genhd.o ioprio.o badblocks.o partitions/ blk-rq-qos.o

obj-$(CONFIG_BOUNCE)		+= bounce.o
obj-$(CONFIG_BLK_SCSI_REQUEST)	+= scsi_ioctl.o
obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o
obj-$(CONFIG_BLK_DEV_BSGLIB)	+= bsg-lib.o
obj-$(CONFIG_BLK_CGROUP)	+= blk-cgroup.o
obj-$(CONFIG_BLK_CGROUP_RWSTAT)	+= blk-cgroup-rwstat.o
obj-$(CONFIG_BLK_DEV_THROTTLING)	+= blk-throttle.o
obj-$(CONFIG_BLK_CGROUP_IOLATENCY)	+= blk-iolatency.o
obj-$(CONFIG_BLK_CGROUP_IOCOST)	+= blk-iocost.o
obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
obj-$(CONFIG_IOSCHED_BFQ)	+= bfq.o

obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
obj-$(CONFIG_BLK_DEV_INTEGRITY) += bio-integrity.o blk-integrity.o
obj-$(CONFIG_BLK_DEV_INTEGRITY_T10)	+= t10-pi.o
obj-$(CONFIG_BLK_MQ_PCI)	+= blk-mq-pci.o
obj-$(CONFIG_BLK_MQ_VIRTIO)	+= blk-mq-virtio.o
obj-$(CONFIG_BLK_MQ_RDMA)	+= blk-mq-rdma.o
obj-$(CONFIG_BLK_DEV_ZONED)	+= blk-zoned.o
obj-$(CONFIG_BLK_WBT)		+= blk-wbt.o
obj-$(CONFIG_BLK_DEBUG_FS)	+= blk-mq-debugfs.o
obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o
obj-$(CONFIG_BLK_SED_OPAL)	+= sed-opal.o
obj-$(CONFIG_BLK_PM)		+= blk-pm.o
obj-$(CONFIG_BLK_INLINE_ENCRYPTION)	+= keyslot-manager.o blk-crypto.o
obj-$(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK)	+= blk-crypto-fallback.o
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