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 <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
> Signed-off-by: Thomas Gleixner <[email protected]>
> ---
>  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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