Re: [PATCH 21/25] x86/mcheck: Split threshold_cpu_callback into two callbacks

[Borislav Petkov <bp@alien8.de>]

On Thu, Nov 03, 2016 at 03:50:17PM +0100, Sebastian Andrzej Siewior wrote:
> The threshold_cpu_callback callbacks looks like one of the notifier and
> its arguments are almost the same. Split this out and have one ONLINE
> and one DEAD callback. This will come handy later once the main code
> gets changed to use the callback mechanism.
> Also, handle threshold_cpu_callback_online() return value so we don't
> continue if the function fails.
> 
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: linux-edac@vger.kernel.org
> Cc: x86@kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  arch/x86/include/asm/mce.h           |  3 ++-
>  arch/x86/kernel/cpu/mcheck/mce.c     | 18 +++++++++++++-----
>  arch/x86/kernel/cpu/mcheck/mce_amd.c | 24 ++++--------------------
>  3 files changed, 19 insertions(+), 26 deletions(-)

...

> -void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
> +int (*threshold_cpu_callback_online)(unsigned int cpu);
> +int (*threshold_cpu_callback_dead)(unsigned int cpu);

Let's get rid of those pointers and pointer testing and export the
create/remove functions directly.

How's that? It builds here.

---

Index: b/arch/x86/include/asm/mce.h
===================================================================
--- a/arch/x86/include/asm/mce.h	2016-11-07 14:06:40.246518729 +0100
+++ b/arch/x86/include/asm/mce.h	2016-11-07 14:17:36.770529205 +0100
@@ -292,9 +292,9 @@ void do_machine_check(struct pt_regs *,
 /*
  * Threshold handler
  */
-
 extern void (*mce_threshold_vector)(void);
-extern void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
+extern int mce_threshold_create_device(unsigned int cpu);
+extern int mce_threshold_remove_device(unsigned int cpu);
 
 /* Deferred error interrupt handler */
 extern void (*deferred_error_int_vector)(void);
Index: b/arch/x86/kernel/cpu/mcheck/mce.c
===================================================================
--- a/arch/x86/kernel/cpu/mcheck/mce.c	2016-11-07 14:06:40.246518729 +0100
+++ b/arch/x86/kernel/cpu/mcheck/mce.c	2016-11-07 14:17:06.186528717 +0100
@@ -2291,8 +2291,6 @@ static struct bus_type mce_subsys = {
 
 DEFINE_PER_CPU(struct device *, mce_device);
 
-void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
-
 static inline struct mce_bank *attr_to_bank(struct device_attribute *attr)
 {
 	return container_of(attr, struct mce_bank, attr);
@@ -2548,13 +2546,17 @@ mce_cpu_callback(struct notifier_block *
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_ONLINE:
+
 		mce_device_create(cpu);
-		if (threshold_cpu_callback)
-			threshold_cpu_callback(action, cpu);
+
+		if (mce_threshold_create_device(cpu)) {
+			mce_device_remove(cpu);
+			return NOTIFY_BAD;
+		}
+
 		break;
 	case CPU_DEAD:
-		if (threshold_cpu_callback)
-			threshold_cpu_callback(action, cpu);
+		mce_threshold_remove_device(cpu);
 		mce_device_remove(cpu);
 		mce_intel_hcpu_update(cpu);
 
Index: b/arch/x86/kernel/cpu/mcheck/mce_amd.c
===================================================================
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c	2016-11-07 14:06:40.246518729 +0100
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c	2016-11-07 14:18:10.506529743 +0100
@@ -55,6 +55,8 @@
 /* Threshold LVT offset is at MSR0xC0000410[15:12] */
 #define SMCA_THR_LVT_OFF	0xF000
 
+static bool thresholding_en;
+
 static const char * const th_names[] = {
 	"load_store",
 	"insn_fetch",
@@ -1097,10 +1099,13 @@ free_out:
 	per_cpu(threshold_banks, cpu)[bank] = NULL;
 }
 
-static void threshold_remove_device(unsigned int cpu)
+int mce_threshold_remove_device(unsigned int cpu)
 {
 	unsigned int bank;
 
+	if (!thresholding_en)
+		return 0;
+
 	for (bank = 0; bank < mca_cfg.banks; ++bank) {
 		if (!(per_cpu(bank_map, cpu) & (1 << bank)))
 			continue;
@@ -1108,15 +1113,19 @@ static void threshold_remove_device(unsi
 	}
 	kfree(per_cpu(threshold_banks, cpu));
 	per_cpu(threshold_banks, cpu) = NULL;
+	return 0;
 }
 
 /* create dir/files for all valid threshold banks */
-static int threshold_create_device(unsigned int cpu)
+int mce_threshold_create_device(unsigned int cpu)
 {
 	unsigned int bank;
 	struct threshold_bank **bp;
 	int err = 0;
 
+	if (!thresholding_en)
+		return 0;
+
 	bp = per_cpu(threshold_banks, cpu);
 	if (bp)
 		return 0;
@@ -1136,40 +1145,23 @@ static int threshold_create_device(unsig
 	}
 	return err;
 err:
-	threshold_remove_device(cpu);
+	mce_threshold_remove_device(cpu);
 	return err;
 }
 
-/* get notified when a cpu comes on/off */
-static void
-amd_64_threshold_cpu_callback(unsigned long action, unsigned int cpu)
-{
-	switch (action) {
-	case CPU_ONLINE:
-	case CPU_ONLINE_FROZEN:
-		threshold_create_device(cpu);
-		break;
-	case CPU_DEAD:
-	case CPU_DEAD_FROZEN:
-		threshold_remove_device(cpu);
-		break;
-	default:
-		break;
-	}
-}
-
 static __init int threshold_init_device(void)
 {
 	unsigned lcpu = 0;
 
 	/* to hit CPUs online before the notifier is up */
 	for_each_online_cpu(lcpu) {
-		int err = threshold_create_device(lcpu);
+		int err = mce_threshold_create_device(lcpu);
 
 		if (err)
 			return err;
 	}
-	threshold_cpu_callback = amd_64_threshold_cpu_callback;
+
+	thresholding_en = true;
 
 	return 0;
 }

-- 
Regards/Gruss,
    Boris.

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