linux-kernel - [RFC Patch Part1 V1 12/30] x86, ioapic: kill static variable nr_irqs

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Message-Id: <1400227550-5935-13-git-send-email-jiang.liu@linux.intel.com>
Date:	Fri, 16 May 2014 16:05:32 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>, x86@...nel.org,
	Jiang Liu <jiang.liu@...ux.intel.com>
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, sfi-devel@...plefirmware.org,
	Ingo Molnar <mingo@...nel.org>
Subject: [RFC Patch Part1 V1 12/30] x86, ioapic: kill static variable nr_irqs_gsi

Static variable nr_irqs_gsi is used to maintain the lowest dynamic
allocatable IRQ number. It may cause trouble when enabling dynamic
IRQ allocation for IOAPIC, so use arch_dynirq_lower_bound() to
avoid directly accessing nr_irqs_gsi and kill nr_irqs_gsi.

Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
---
 arch/x86/kernel/apic/io_apic.c |   35 ++++++++---------------------------
 1 file changed, 8 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 2c91a7fc9915..fe515583a927 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -118,9 +118,6 @@ struct mpc_intsrc mp_irqs[MAX_IRQ_SOURCES];
 /* # of MP IRQ source entries */
 int mp_irq_entries;
 
-/* GSI interrupts */
-static int nr_irqs_gsi = NR_IRQS_LEGACY;
-
 #ifdef CONFIG_EISA
 int mp_bus_id_to_type[MAX_MP_BUSSES];
 #endif
@@ -2921,9 +2918,7 @@ unsigned int __create_irqs(unsigned int from, unsigned int count, int node)
 	unsigned long flags;
 	int irq, i;
 
-	if (from < nr_irqs_gsi)
-		from = nr_irqs_gsi;
-
+	from = arch_dynirq_lower_bound(from);
 	cfg = kzalloc_node(count * sizeof(cfg[0]), GFP_KERNEL, node);
 	if (!cfg)
 		return 0;
@@ -2972,12 +2967,9 @@ unsigned int create_irq_nr(unsigned int from, int node)
 int create_irq(void)
 {
 	int node = cpu_to_node(0);
-	unsigned int irq_want;
 	int irq;
 
-	irq_want = nr_irqs_gsi;
-	irq = create_irq_nr(irq_want, node);
-
+	irq = create_irq_nr(arch_dynirq_lower_bound(0), node);
 	if (irq == 0)
 		irq = -1;
 
@@ -3142,7 +3134,7 @@ int native_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 		return 1;
 
 	node = dev_to_node(&dev->dev);
-	irq_want = nr_irqs_gsi;
+	irq_want = arch_dynirq_lower_bound(0);
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
 		irq = create_irq_nr(irq_want, node);
 		if (irq == 0)
@@ -3406,20 +3398,11 @@ static int __init io_apic_get_redir_entries(int ioapic)
 	return reg_01.bits.entries + 1;
 }
 
-static void __init probe_nr_irqs_gsi(void)
-{
-	int nr;
-
-	nr = gsi_top + NR_IRQS_LEGACY;
-	if (nr > nr_irqs_gsi)
-		nr_irqs_gsi = nr;
-
-	printk(KERN_DEBUG "nr_irqs_gsi: %d\n", nr_irqs_gsi);
-}
-
 unsigned int arch_dynirq_lower_bound(unsigned int from)
 {
-	return from < nr_irqs_gsi ? nr_irqs_gsi : from;
+	unsigned int min = gsi_top + NR_IRQS_LEGACY;
+
+	return from < min ? min : from;
 }
 
 int __init arch_probe_nr_irqs(void)
@@ -3429,12 +3412,12 @@ int __init arch_probe_nr_irqs(void)
 	if (nr_irqs > (NR_VECTORS * nr_cpu_ids))
 		nr_irqs = NR_VECTORS * nr_cpu_ids;
 
-	nr = nr_irqs_gsi + 8 * nr_cpu_ids;
+	nr = (gsi_top + NR_IRQS_LEGACY) + 8 * nr_cpu_ids;
 #if defined(CONFIG_PCI_MSI) || defined(CONFIG_HT_IRQ)
 	/*
 	 * for MSI and HT dyn irq
 	 */
-	nr += nr_irqs_gsi * 16;
+	nr += (gsi_top + NR_IRQS_LEGACY) * 16;
 #endif
 	if (nr < nr_irqs)
 		nr_irqs = nr;
@@ -3707,8 +3690,6 @@ fake_ioapic_page:
 		ioapic_res->end = ioapic_phys + IO_APIC_SLOT_SIZE - 1;
 		ioapic_res++;
 	}
-
-	probe_nr_irqs_gsi();
 }
 
 void __init ioapic_insert_resources(void)
-- 
1.7.10.4

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