The patch titled
x86_64 irq: Only look at per_cpu data for online cpus.
has been added to the -mm tree. Its filename is
x86_64-irq-only-look-at-per_cpu-data-for-online-cpus.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: x86_64 irq: Only look at per_cpu data for online cpus.
From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
When I generalized __assign_irq_vector I failed to pay attention to what
happens when you access a per cpu data structure for a cpu that is not
online. It is an undefined case making any code that does it have
undefined behavior as well.
The code still needs to be able to allocate a vector across cpus that are
not online to properly handle combinations like lowest priority interrupt
delivery and cpu_hotplug. Not that we can do that today but the
infrastructure shouldn't prevent it.
So this patch updates the places where we touch per cpu data to only touch
online cpus, it makes cpu vector allocation an atomic operation with
respect to cpu hotplug, and it updates the cpu start code to properly
initialize vector_irq so we don't have inconsistencies.
Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Acked-by: Yinghai Lu <yinghai.lu@xxxxxxx>
Acked-by: Muli Ben-Yehuda <muli@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/x86_64/kernel/io_apic.c | 42 +++++++++++++++++++++++++++++----
arch/x86_64/kernel/smpboot.c | 7 ++++-
include/asm-x86_64/hw_irq.h | 2 +
3 files changed, 45 insertions(+), 6 deletions(-)
diff -puN arch/x86_64/kernel/io_apic.c~x86_64-irq-only-look-at-per_cpu-data-for-online-cpus arch/x86_64/kernel/io_apic.c
--- a/arch/x86_64/kernel/io_apic.c~x86_64-irq-only-look-at-per_cpu-data-for-online-cpus
+++ a/arch/x86_64/kernel/io_apic.c
@@ -63,7 +63,7 @@ int timer_over_8254 __initdata = 0;
static struct { int pin, apic; } ioapic_i8259 = { -1, -1 };
static DEFINE_SPINLOCK(ioapic_lock);
-static DEFINE_SPINLOCK(vector_lock);
+DEFINE_SPINLOCK(vector_lock);
/*
* # of IRQ routing registers
@@ -618,6 +618,9 @@ static int __assign_irq_vector(int irq,
BUG_ON((unsigned)irq >= NR_IRQ_VECTORS);
+ /* Only try and allocate irqs on cpus that are present */
+ cpus_and(mask, mask, cpu_online_map);
+
if (irq_vector[irq] > 0)
old_vector = irq_vector[irq];
if (old_vector > 0) {
@@ -627,11 +630,12 @@ static int __assign_irq_vector(int irq,
}
for_each_cpu_mask(cpu, mask) {
- cpumask_t domain;
+ cpumask_t domain, new_mask;
int new_cpu;
int vector, offset;
domain = vector_allocation_domain(cpu);
+ cpus_and(new_mask, domain, cpu_online_map);
vector = current_vector;
offset = current_offset;
@@ -646,18 +650,20 @@ next:
continue;
if (vector == IA32_SYSCALL_VECTOR)
goto next;
- for_each_cpu_mask(new_cpu, domain)
+ for_each_cpu_mask(new_cpu, new_mask)
if (per_cpu(vector_irq, new_cpu)[vector] != -1)
goto next;
/* Found one! */
current_vector = vector;
current_offset = offset;
if (old_vector >= 0) {
+ cpumask_t old_mask;
int old_cpu;
- for_each_cpu_mask(old_cpu, irq_domain[irq])
+ cpus_and(old_mask, irq_domain[irq], cpu_online_map);
+ for_each_cpu_mask(old_cpu, old_mask)
per_cpu(vector_irq, old_cpu)[old_vector] = -1;
}
- for_each_cpu_mask(new_cpu, domain)
+ for_each_cpu_mask(new_cpu, new_mask)
per_cpu(vector_irq, new_cpu)[vector] = irq;
irq_vector[irq] = vector;
irq_domain[irq] = domain;
@@ -678,6 +684,32 @@ static int assign_irq_vector(int irq, cp
return vector;
}
+void __setup_vector_irq(int cpu)
+{
+ /* Initialize vector_irq on a new cpu */
+ /* This function must be called with vector_lock held */
+ unsigned long flags;
+ int irq, vector;
+
+
+ /* Mark the inuse vectors */
+ for (irq = 0; irq < NR_IRQ_VECTORS; ++irq) {
+ if (!cpu_isset(cpu, irq_domain[irq]))
+ continue;
+ vector = irq_vector[irq];
+ per_cpu(vector_irq, cpu)[vector] = irq;
+ }
+ /* Mark the free vectors */
+ for (vector = 0; vector < NR_VECTORS; ++vector) {
+ irq = per_cpu(vector_irq, cpu)[vector];
+ if (irq < 0)
+ continue;
+ if (!cpu_isset(cpu, irq_domain[irq]))
+ per_cpu(vector_irq, cpu)[vector] = -1;
+ }
+}
+
+
extern void (*interrupt[NR_IRQS])(void);
static struct irq_chip ioapic_chip;
diff -puN arch/x86_64/kernel/smpboot.c~x86_64-irq-only-look-at-per_cpu-data-for-online-cpus arch/x86_64/kernel/smpboot.c
--- a/arch/x86_64/kernel/smpboot.c~x86_64-irq-only-look-at-per_cpu-data-for-online-cpus
+++ a/arch/x86_64/kernel/smpboot.c
@@ -581,12 +581,16 @@ void __cpuinit start_secondary(void)
* smp_call_function().
*/
lock_ipi_call_lock();
+ spin_lock(&vector_lock);
+ /* Setup the per cpu irq handling data structures */
+ __setup_vector_irq(smp_processor_id());
/*
* Allow the master to continue.
*/
cpu_set(smp_processor_id(), cpu_online_map);
per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
+ spin_unlock(&vector_lock);
unlock_ipi_call_lock();
cpu_idle();
@@ -799,7 +803,6 @@ static int __cpuinit do_boot_cpu(int cpu
cpu, node);
}
-
alternatives_smp_switch(1);
c_idle.idle = get_idle_for_cpu(cpu);
@@ -1246,8 +1249,10 @@ int __cpu_disable(void)
local_irq_disable();
remove_siblinginfo(cpu);
+ spin_lock(&vector_lock);
/* It's now safe to remove this processor from the online map */
cpu_clear(cpu, cpu_online_map);
+ spin_unlock(&vector_lock);
remove_cpu_from_maps();
fixup_irqs(cpu_online_map);
return 0;
diff -puN include/asm-x86_64/hw_irq.h~x86_64-irq-only-look-at-per_cpu-data-for-online-cpus include/asm-x86_64/hw_irq.h
--- a/include/asm-x86_64/hw_irq.h~x86_64-irq-only-look-at-per_cpu-data-for-online-cpus
+++ a/include/asm-x86_64/hw_irq.h
@@ -76,6 +76,8 @@
#ifndef __ASSEMBLY__
typedef int vector_irq_t[NR_VECTORS];
DECLARE_PER_CPU(vector_irq_t, vector_irq);
+extern void __setup_vector_irq(int cpu);
+extern spinlock_t vector_lock;
/*
* Various low-level irq details needed by irq.c, process.c,
_
Patches currently in -mm which might be from ebiederm@xxxxxxxxxxxx are
origin.patch
x86_64-irq-use-irq_domain-in-ioapic_retrigger_irq.patch
x86_64-put-more-than-one-cpu-in-target_cpus.patch
x86_64-irq-simplify-the-vector-allocator.patch
x86_64-irq-only-look-at-per_cpu-data-for-online-cpus.patch
improve-the-remove-sysctl-warnings.patch
add-process_session-helper-routine.patch
rename-struct-namespace-to-struct-mnt_namespace.patch
add-an-identifier-to-nsproxy.patch
rename-struct-pspace-to-struct-pid_namespace.patch
add-pid_namespace-to-nsproxy.patch
use-current-nsproxy-pid_ns.patch
add-child-reaper-to-pid_namespace.patch
rename-struct-namespace-to-struct-mnt_namespace-cachefiles.patch
pidhash-temporary-debug-checks.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
