linux/include
Thomas Gleixner a899418167 hotplug: Prevent alloc/free of irq descriptors during cpu up/down
When a cpu goes up some architectures (e.g. x86) have to walk the irq
space to set up the vector space for the cpu. While this needs extra
protection at the architecture level we can avoid a few race
conditions by preventing the concurrent allocation/free of irq
descriptors and the associated data.

When a cpu goes down it moves the interrupts which are targeted to
this cpu away by reassigning the affinities. While this happens
interrupts can be allocated and freed, which opens a can of race
conditions in the code which reassignes the affinities because
interrupt descriptors might be freed underneath.

Example:

CPU1				CPU2
cpu_up/down
 irq_desc = irq_to_desc(irq);
				remove_from_radix_tree(desc);
 raw_spin_lock(&desc->lock);
				free(desc);

We could protect the irq descriptors with RCU, but that would require
a full tree change of all accesses to interrupt descriptors. But
fortunately these kind of race conditions are rather limited to a few
things like cpu hotplug. The normal setup/teardown is very well
serialized. So the simpler and obvious solution is:

Prevent allocation and freeing of interrupt descriptors accross cpu
hotplug.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: xiao jin <jin.xiao@intel.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Link: http://lkml.kernel.org/r/20150705171102.063519515@linutronix.de
2015-07-08 11:32:25 +02:00
..
acpi Additional ACPICA material for v4.2-rc1 2015-07-02 17:11:28 -07:00
asm-generic - Support for HS38 cores based on ARCv2 ISA 2015-07-01 09:24:26 -07:00
clocksource ARM: 8366/1: move Dual-Timer SP804 driver to drivers/clocksource 2015-06-02 09:58:18 +01:00
crypto crypto: rng - Do not free default RNG when it becomes unused 2015-06-22 15:49:18 +08:00
drm drm: use kvfree() in drm_free_large() 2015-06-30 19:44:59 -07:00
dt-bindings The changes to the common clock framework for 4.2 are dominated by new 2015-07-01 19:22:00 -07:00
keys
kvm
linux hotplug: Prevent alloc/free of irq descriptors during cpu up/down 2015-07-08 11:32:25 +02:00
math-emu
media Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds 2015-07-01 19:09:11 -07:00
memory
misc cxl: Add AFU virtual PHB and kernel API 2015-06-03 13:27:20 +10:00
net net: Kill sock->sk_protinfo 2015-06-28 16:55:44 -07:00
pcmcia
ras tracing: add trace event for memory-failure 2015-06-24 17:49:43 -07:00
rdma IB/mad: Add final OPA MAD processing 2015-06-12 14:49:18 -04:00
rxrpc
scsi SCSI misc on 20150622 2015-06-23 15:55:44 -07:00
soc Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2015-06-26 12:20:00 -07:00
sound ASoC: Further updates for v4.2 2015-06-22 11:32:41 +02:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-07-04 14:13:43 -07:00
trace Merge branch 'for-linus-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2015-06-30 20:07:45 -07:00
uapi virtio/vhost: cross endian support 2015-07-03 16:02:25 -07:00
video Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-06-26 13:18:51 -07:00
xen
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