From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: bp@suse.de, hpa@zytor.com, tglx@linutronix.de, jroedel@suse.de,
peterz@infradead.org, jin.xiao@intel.com,
linux-kernel@vger.kernel.org, yanmin_zhang@linux.intel.com,
mingo@kernel.org
Subject: [tip:irq/urgent] hotplug: Prevent alloc/ free of irq descriptors during cpu up/down
Date: Tue, 7 Jul 2015 13:06:33 -0700 [thread overview]
Message-ID: <tip-bdcbafe3402cb337752c4c8bce3445ee4c5559a5@git.kernel.org> (raw)
In-Reply-To: <20150705171102.063519515@linutronix.de>
Commit-ID: bdcbafe3402cb337752c4c8bce3445ee4c5559a5
Gitweb: http://git.kernel.org/tip/bdcbafe3402cb337752c4c8bce3445ee4c5559a5
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Sun, 5 Jul 2015 17:12:30 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 7 Jul 2015 22:03:22 +0200
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
---
kernel/cpu.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index fa6dc67..6a37454 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -21,6 +21,7 @@
#include <linux/suspend.h>
#include <linux/lockdep.h>
#include <linux/tick.h>
+#include <linux/irq.h>
#include <trace/events/power.h>
#include "smpboot.h"
next prev parent reply other threads:[~2015-07-07 20:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-05 17:12 [patch 0/4] x86/irq: Plug a couple of cpu hotplug races Thomas Gleixner
2015-07-05 17:12 ` [patch 1/4] hotplug: Prevent alloc/free of irq descriptors during cpu up/down Thomas Gleixner
2015-07-07 9:48 ` [tip:irq/urgent] hotplug: Prevent alloc/ free " tip-bot for Thomas Gleixner
2015-07-07 20:06 ` tip-bot for Thomas Gleixner [this message]
2015-07-08 9:37 ` tip-bot for Thomas Gleixner
2015-07-14 14:39 ` [patch 1/4] hotplug: Prevent alloc/free " Boris Ostrovsky
2015-07-14 15:44 ` Thomas Gleixner
2015-07-14 16:03 ` Boris Ostrovsky
2015-07-14 17:32 ` Thomas Gleixner
2015-07-14 20:04 ` [Xen-devel] " Boris Ostrovsky
2015-07-14 20:15 ` Thomas Gleixner
2015-07-14 21:07 ` Boris Ostrovsky
2016-03-12 9:19 ` Thomas Gleixner
2016-03-14 13:12 ` Boris Ostrovsky
2015-07-05 17:12 ` [patch 2/4] x86: Plug irq vector hotplug race Thomas Gleixner
2015-07-07 9:57 ` [tip:x86/urgent] x86/irq: " tip-bot for Thomas Gleixner
2015-07-05 17:12 ` [patch 3/4] x86/irq: Use proper locking in check_irq_vectors_for_cpu_disable() Thomas Gleixner
2015-07-07 9:57 ` [tip:x86/urgent] " tip-bot for Thomas Gleixner
2015-07-05 17:12 ` [patch 4/4] x86/irq: Retrieve irq data after locking irq_desc Thomas Gleixner
2015-07-07 9:58 ` [tip:x86/urgent] " tip-bot for Thomas Gleixner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=tip-bdcbafe3402cb337752c4c8bce3445ee4c5559a5@git.kernel.org \
--to=tipbot@zytor.com \
--cc=bp@suse.de \
--cc=hpa@zytor.com \
--cc=jin.xiao@intel.com \
--cc=jroedel@suse.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=yanmin_zhang@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).