[tip:smp/hotplug] x86/mcheck: Be prepared for a rollback back to the ONLINE state

[tip-bot for Sebastian Andrzej Siewior]

Commit-ID:  7f34b935e8bf2f5304fce273a8fa98c63886d686
Gitweb:     http://git.kernel.org/tip/7f34b935e8bf2f5304fce273a8fa98c63886d686
Author:     Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate: Thu, 10 Nov 2016 18:44:43 +0100
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 16 Nov 2016 09:34:17 +0100

x86/mcheck: Be prepared for a rollback back to the ONLINE state

If we try a CPU down and fail in the middle then we roll back to the
online state. This means we would perform CPU_ONLINE / mce_device_create()
without invoking CPU_DEAD / mce_device_remove() for the cleanup of what was
allocated in CPU_ONLINE.

Be prepared for this and don't allocate the struct if we have it
already.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: rt@xxxxxxxxxxxxx
Cc: linux-edac@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20161110174447.11848-4-bigeasy@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

---
 arch/x86/kernel/cpu/mcheck/mce.c     | 4 ++++
 arch/x86/kernel/cpu/mcheck/mce_amd.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index a7fdf45..e9ffd6d 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -2409,6 +2409,10 @@ static int mce_device_create(unsigned int cpu)
 	if (!mce_available(&boot_cpu_data))
 		return -EIO;
 
+	dev = per_cpu(mce_device, cpu);
+	if (dev)
+		return 0;
+
 	dev = kzalloc(sizeof *dev, GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index 55cd018..e93580c 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -1097,6 +1097,10 @@ static int threshold_create_device(unsigned int cpu)
 	struct threshold_bank **bp;
 	int err = 0;
 
+	bp = per_cpu(threshold_banks, cpu);
+	if (bp)
+		return 0;
+
 	bp = kzalloc(sizeof(struct threshold_bank *) * mca_cfg.banks,
 		     GFP_KERNEL);
 	if (!bp)