linux-kernel - Re: [PATCH] x86: move dmar_table_init out of enable

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Date:	Mon, 17 Aug 2009 13:47:10 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Gleb Natapov <gleb@...hat.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
Subject: Re: [PATCH] x86: move dmar_table_init out of enable_IR

Suresh Siddha wrote:
> On Mon, 2009-08-17 at 11:19 -0700, Yinghai Lu wrote:
>> ---
>>  arch/x86/kernel/apic/apic.c |   22 +++++++++++++---------
>>  1 file changed, 13 insertions(+), 9 deletions(-)
>>
>> Index: linux-2.6/arch/x86/kernel/apic/apic.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/kernel/apic/apic.c
>> +++ linux-2.6/arch/x86/kernel/apic/apic.c
>> @@ -1365,14 +1365,6 @@ void enable_x2apic(void)
>>  int __init enable_IR(void)
>>  {
>>  #ifdef CONFIG_INTR_REMAP
>> -	int ret;
>> -
>> -	ret = dmar_table_init();
>> -	if (ret) {
>> -		pr_debug("dmar_table_init() failed with %d:\n", ret);
>> -		return 0;
>> -	}
>> -
>>  	if (!intr_remapping_supported()) {
>>  		pr_debug("intr-remapping not supported\n");
>>  		return 0;
>> @@ -1400,6 +1392,14 @@ void __init enable_IR_x2apic(void)
>>  	unsigned long flags;
>>  	struct IO_APIC_route_entry **ioapic_entries = NULL;
>>  	int ret, x2apic_enabled = 0;
>> +	int dmar_table_init_ret = 0;
>> +
>> +#ifdef CONFIG_INTR_REMAP
>> +	dmar_table_init_ret = dmar_table_init();
>> +	if (dmar_table_init_ret)
>> +		pr_debug("dmar_table_init() failed with %d:\n",
>> +				dmar_table_init_ret);
>> +#endif
> 
> We can remove this ifdef check, as dmar_table_init() already handles
> the !config_intr_remap
> 
> Also, at this error condition, we should simply return if the cpu has no
> x2apic support. There is no x2apic support and we failed to enable
> interrupt-remapping. No need to go further down.

like this ?

---
 arch/x86/kernel/apic/apic.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

Index: linux-2.6/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/apic.c
+++ linux-2.6/arch/x86/kernel/apic/apic.c
@@ -1392,14 +1392,11 @@ void __init enable_IR_x2apic(void)
 	unsigned long flags;
 	struct IO_APIC_route_entry **ioapic_entries = NULL;
 	int ret, x2apic_enabled = 0;
-	int dmar_table_init_ret = 0;
+	int dmar_table_init_ret;
 
-#ifdef CONFIG_INTR_REMAP
 	dmar_table_init_ret = dmar_table_init();
-	if (dmar_table_init_ret)
-		pr_debug("dmar_table_init() failed with %d:\n",
-				dmar_table_init_ret);
-#endif
+	if (dmar_table_init_ret && !x2apic_supported())
+		return;
 
 	ioapic_entries = alloc_ioapic_entries();
 	if (!ioapic_entries) {



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