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Subject[tip:smp/hotplug] cpu/hotplug: Prevent alloc/free of irq descriptors during CPU up/down (again)
Commit-ID:  aa877175e7a9982233ed8f10cb4bfddd78d82741
Gitweb: http://git.kernel.org/tip/aa877175e7a9982233ed8f10cb4bfddd78d82741
Author: Boris Ostrovsky <boris.ostrovsky@oracle.com>
AuthorDate: Wed, 3 Aug 2016 13:22:28 -0400
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 10 Aug 2016 15:42:57 +0200

cpu/hotplug: Prevent alloc/free of irq descriptors during CPU up/down (again)

Now that Xen no longer allocates irqs in _cpu_up() we can restore
commit:

a89941816726 ("hotplug: Prevent alloc/free of irq descriptors during cpu up/down")

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: david.vrabel@citrix.com
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1470244948-17674-3-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/smpboot.c | 11 -----------
kernel/cpu.c | 8 ++++++++
2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 2a6e84a..067de61 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1108,17 +1108,8 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)

common_cpu_up(cpu, tidle);

- /*
- * We have to walk the irq descriptors to setup the vector
- * space for the cpu which comes online. Prevent irq
- * alloc/free across the bringup.
- */
- irq_lock_sparse();
-
err = do_boot_cpu(apicid, cpu, tidle);
-
if (err) {
- irq_unlock_sparse();
pr_err("do_boot_cpu failed(%d) to wakeup CPU#%u\n", err, cpu);
return -EIO;
}
@@ -1136,8 +1127,6 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
touch_nmi_watchdog();
}

- irq_unlock_sparse();
-
return 0;
}

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 341bf80..ec12b72 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -349,8 +349,16 @@ static int bringup_cpu(unsigned int cpu)
struct task_struct *idle = idle_thread_get(cpu);
int ret;

+ /*
+ * Some architectures have to walk the irq descriptors to
+ * setup the vector space for the cpu which comes online.
+ * Prevent irq alloc/free across the bringup.
+ */
+ irq_lock_sparse();
+
/* Arch-specific enabling code. */
ret = __cpu_up(cpu, idle);
+ irq_unlock_sparse();
if (ret) {
cpu_notify(CPU_UP_CANCELED, cpu);
return ret;
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