[PATCH] - Complete IRQ interrupt migration in arch_enable_uv_irq()

[PATCH] - Complete IRQ interrupt migration in arch_enable_uv_irq()

[Jack Steiner]

In uv_setup_irq(), the call to create_irq() initially assigns IRQ
vectors to cpu 0. The subsequent call to assign_irq_vector() in
arch_enable_uv_irq() migrates the IRQ to another cpu and frees the cpu
0 vector - at least it will be freed as soon as the "IRQ move"
completes. 

arch_enable_uv_irq() needs to send a cleanup IPI to complete the IRQ move.
Otherwise, assignment of GRU interrupts on large systems (>200 cpus)
will exhaust the cpu 0 interrupt vectors and initialization of the GRU
driver will fail.

Signed-off-by: Jack Steiner <steiner@sgi.com>


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

Index: linux/arch/x86/kernel/apic/io_apic.c
===================================================================
--- linux.orig/arch/x86/kernel/apic/io_apic.c	2009-07-20 07:55:46.000000000 -0500
+++ linux/arch/x86/kernel/apic/io_apic.c	2009-07-20 07:56:33.000000000 -0500
@@ -3737,6 +3737,9 @@ int arch_enable_uv_irq(char *irq_name, u
 	mmr_pnode = uv_blade_to_pnode(mmr_blade);
 	uv_write_global_mmr64(mmr_pnode, mmr_offset, mmr_value);
 
+	if (cfg->move_in_progress)
+		send_cleanup_vector(cfg);
+
 	return irq;
 }
 

[tip:x86/urgent] x86, UV: Complete IRQ interrupt migration in arch_enable_uv_irq()

[tip-bot for Jack Steiner]

Commit-ID:  2a5ef41661b56cf4eee042a6967c4e14b63e8eac
Gitweb:     http://git.kernel.org/tip/2a5ef41661b56cf4eee042a6967c4e14b63e8eac
Author:     Jack Steiner <steiner@sgi.com>
AuthorDate: Mon, 20 Jul 2009 09:28:41 -0500
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 4 Aug 2009 16:32:52 +0200

x86, UV: Complete IRQ interrupt migration in arch_enable_uv_irq()

In uv_setup_irq(), the call to create_irq() initially assigns
IRQ vectors to cpu 0. The subsequent call to
assign_irq_vector() in arch_enable_uv_irq() migrates the IRQ to
another cpu and frees the cpu 0 vector - at least it will be
freed as soon as the "IRQ move" completes.

arch_enable_uv_irq() needs to send a cleanup IPI to complete
the IRQ move. Otherwise, assignment of GRU interrupts on large
systems (>200 cpus) will exhaust the cpu 0 interrupt vectors
and initialization of the GRU driver will fail.

Signed-off-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20090720142840.GA8885@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 arch/x86/kernel/apic/io_apic.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 2284a48..d2ed6c5 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3793,6 +3793,9 @@ int arch_enable_uv_irq(char *irq_name, unsigned int irq, int cpu, int mmr_blade,
 	mmr_pnode = uv_blade_to_pnode(mmr_blade);
 	uv_write_global_mmr64(mmr_pnode, mmr_offset, mmr_value);
 
+	if (cfg->move_in_progress)
+		send_cleanup_vector(cfg);
+
 	return irq;
 }