Commit-ID:  aa877175e7a9982233ed8f10cb4bfddd78d82741
Gitweb:     http://git.kernel.org/tip/aa877175e7a9982233ed8f10cb4bfddd78d82741
Author:     Boris Ostrovsky <boris.ostrov...@oracle.com>
AuthorDate: Wed, 3 Aug 2016 13:22:28 -0400
Committer:  Ingo Molnar <mi...@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.ostrov...@oracle.com>
Reviewed-by: Juergen Gross <jgr...@suse.com>
Acked-by: Thomas Gleixner <t...@linutronix.de>
Cc: Anna-Maria Gleixner <anna-ma...@linutronix.de>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: david.vra...@citrix.com
Cc: xen-de...@lists.xenproject.org
Link: 
http://lkml.kernel.org/r/1470244948-17674-3-git-send-email-boris.ostrov...@oracle.com
Signed-off-by: Ingo Molnar <mi...@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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