Re: [PATCH 3/3] EDAC: carve out AMD MCE decoding logic

Borislav Petkov
2009-10-03T06:57:57Z

On Fri, Oct 02, 2009 at 08:47:14PM +0200, Ingo Molnar wrote:
> No, the locking was all that i meant. Using atomic_notifier would solve
> that. Make the default decoder low-prio, that way there's no need to do
> the callback save/restore sequence either.

Ok, how's that for starters, it has been only compile-tested and it
looks straight-forward enough to me...

--
diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index f1363b7..9bb1756 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -214,5 +214,7 @@ void intel_init_thermal(struct cpuinfo_x86 *c);

void mce_log_therm_throt_event(__u64 status);

+int mce_register_decoder_notifier(struct notifier_block *nb);
+int mce_unregister_decoder_notifier(struct notifier_block *nb);
#endif /* __KERNEL__ */
#endif /* _ASM_X86_MCE_H */
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index b1598a9..e767cce 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -85,18 +85,36 @@ static DECLARE_WAIT_QUEUE_HEAD(mce_wait);
static DEFINE_PER_CPU(struct mce, mces_seen);
static int cpu_missing;

-static void default_decode_mce(struct mce *m)
+static ATOMIC_NOTIFIER_HEAD(mce_decoder_chain);
+
+/*
+ * CPU/chipset specific EDAC code can register a notifier call here to print
+ * MCE errors in a human-readable form.
+ */
+int mce_register_decoder_notifier(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_register(&mce_decoder_chain, nb);
+}
+EXPORT_SYMBOL_GPL(mce_register_decoder_notifier);
+
+int mce_unregister_decoder_notifier(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_unregister(&mce_decoder_chain, nb);
+}
+EXPORT_SYMBOL_GPL(mce_unregister_decoder_notifier);
+
+static int default_decode_mce(struct notifier_block *nb, unsigned long val,
+ void *data)
{
pr_emerg("No human readable MCE decoding support on this CPU type.\n");
pr_emerg("Run the message through 'mcelog --ascii' to decode.\n");
+
+ return NOTIFY_STOP;
}

-/*
- * CPU/chipset specific EDAC code can register a callback here to print
- * MCE errors in a human-readable form:
- */
-void (*x86_mce_decode_callback)(struct mce *m) = default_decode_mce;
-EXPORT_SYMBOL(x86_mce_decode_callback);
+static struct notifier_block mce_dec_nb = {
+ .notifier_call = default_decode_mce,
+};

/* MCA banks polled by the period polling timer for corrected events */
DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = {
@@ -204,9 +222,9 @@ static void print_mce(struct mce *m)

/*
* Print out human-readable details about the MCE error,
- * (if the CPU has an implementation for that):
+ * (if the CPU has an implementation for that)
*/
- x86_mce_decode_callback(m);
+ atomic_notifier_call_chain(&mce_decoder_chain, 0, m);
}

static void print_mce_head(void)
@@ -1420,6 +1438,8 @@ void __cpuinit mcheck_init(struct cpuinfo_x86 *c)
mce_cpu_features(c);
mce_init_timer();
INIT_WORK(&__get_cpu_var(mce_work), mce_process_work);
+
+ mce_register_decoder_notifier(&mce_dec_nb);
}

/*
diff --git a/drivers/edac/edac_mce_amd.c b/drivers/edac/edac_mce_amd.c
index 713ed7d..aa0061e 100644
--- a/drivers/edac/edac_mce_amd.c
+++ b/drivers/edac/edac_mce_amd.c
@@ -363,8 +363,10 @@ static inline void amd_decode_err_code(unsigned int ec)
pr_warning("Huh? Unknown MCE error 0x%x\n", ec);
}

-static void amd_decode_mce(struct mce *m)
+static int amd_decode_mce(struct notifier_block *nb, unsigned long val,
+ void *data)
{
+ struct mce *m = (struct mce *)data;
struct err_regs regs;
int node, ecc;

@@ -420,20 +422,23 @@ static void amd_decode_mce(struct mce *m)
}

amd_decode_err_code(m->status & 0xffff);
+
+ return NOTIFY_STOP;
}

+static struct notifier_block amd_mce_dec_nb = {
+ .notifier_call = amd_decode_mce,
+ .priority = 100,
+};
+
static int __init mce_amd_init(void)
{
/*
* We can decode MCEs for Opteron and later CPUs:
*/
if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
- (boot_cpu_data.x86 >= 0xf)) {
- /* safe the default decode mce callback */
- orig_mce_callback = x86_mce_decode_callback;
-
- x86_mce_decode_callback = amd_decode_mce;
- }
+ (boot_cpu_data.x86 >= 0xf))
+ mce_register_decoder_notifier(&amd_mce_dec_nb);

return 0;
}
@@ -442,7 +447,7 @@ early_initcall(mce_amd_init);
#ifdef MODULE
static void __exit mce_amd_exit(void)
{
- x86_mce_decode_callback = orig_mce_callback;
+ mce_unregister_decoder_notifier(&amd_mce_dec_nb);
}

MODULE_DESCRIPTION("AMD MCE decoder");

--
Regards/Gruss,
Boris.