| title: | RFC Convert sparse irq lock to raw spinlock |
|
Moving of IRQs is done in hardirq context so the sparse_irq_lock needs to be
raw_spinlock_t. For this to work we need to move the memory allocation before
actually taking the lock itself.
This patch doesnt seem to do 100% the right thing since I still get the
following from lockdep:
[ INFO: inconsistent lock state ]
2.6.29.4-rt16-rt #2
---------------------------------
inconsistent {HARDIRQ-ON-W} - {IN-HARDIRQ-W} usage.
swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
(per_cpu__lock_slab_locked#5){?.+...}, at: [<ffffffff802f85d5 ]
_slab_irq_disab
le+0x40/0x63
{HARDIRQ-ON-W} state was registered at:
[<ffffffff80287b64 ] mark_lock+0x296/0x3ed
[<ffffffff80287d79 ] mark_irqflags+0xbe/0x125
[<ffffffff8028a2a8 ] __lock_acquire+0x692/0x855
[<ffffffff8028a56f ] lock_acquire+0x104/0x130
[<ffffffff804e9e50 ] rt_spin_lock+0x7d/0x81
[<ffffffff804e70ee ] cpuup_callback+0x48/0x229
[<ffffffff804ee098 ] notifier_call_chain+0x33/0x5b
[<ffffffff8027d463 ] __raw_notifier_call_chain+0x9/0xb
[<ffffffff804e57ee ] _cpu_up+0x75/0x12e
[<ffffffff804e5908 ] cpu_up+0x61/0x76
[<ffffffff8079466b ] smp_init+0x52/0xa0
[<ffffffff80794787 ] kernel_init+0x80/0x19b
[<ffffffff8022609a ] child_rip+0xa/0x20
[<ffffffffffffffff ] 0xffffffffffffffff
irq event stamp: 119862
hardirqs last enabled at (119861): [<ffffffff802b6622 ]
__rcu_read_lock+0xa9/0x
bc
hardirqs last disabled at (119862): [<ffffffff80224d3a ] save_args+0x6a/0x70
softirqs last enabled at (0): [<ffffffff80262759 ] copy_process+0x573/0x111f
softirqs last disabled at (0): [<(null) ] (null)
other info that might help us debug this:
1 lock held by swapper/0:
#0: (&irq_desc_lock_class){-.....}, at: [<ffffffff802b430d ]
handle_fasteoi_ir
q+0x20/0xff
stack backtrace:
Pid: 0, comm: swapper Tainted: G N 2.6.29.4-rt16-rt #2
Call Trace:
[<ffffffff80227cba ] dump_trace+0xda/0x3d0
[<ffffffff80228a6f ] show_trace_log_lvl+0x4c/0x58
[<ffffffff80228a8b ] show_trace+0x10/0x12
[<ffffffff804e7691 ] dump_stack+0x72/0x7b
[<ffffffff802876a0 ] print_usage_bug+0x1ce/0x1df
[<ffffffff80287766 ] mark_lock_irq+0xb5/0x21d
[<ffffffff80287b88 ] mark_lock+0x2ba/0x3ed
[<ffffffff80287d0f ] mark_irqflags+0x54/0x125
[<ffffffff8028a2a8 ] __lock_acquire+0x692/0x855
[<ffffffff8028a56f ] lock_acquire+0x104/0x130
[<ffffffff804e9e50 ] rt_spin_lock+0x7d/0x81
[<ffffffff802f85d5 ] _slab_irq_disable+0x40/0x63
[<ffffffff802fa520 ] kmem_cache_alloc_node+0x41/0x225
[<ffffffff802b5349 ] __real_move_irq_desc+0x44/0x1bd
[<ffffffff802b5504 ] move_irq_desc+0x42/0x56
[<ffffffff8023c0be ] irq_complete_move+0x80/0x95
[<ffffffff8023d91b ] ack_apic_level+0x20/0x101
[<ffffffff802b43cf ] handle_fasteoi_irq+0xe2/0xff
[<ffffffff8022764f ] handle_irq+0x1f/0x27
[<ffffffff80226db6 ] do_IRQ+0x5e/0xc6
[<ffffffff80225953 ] ret_from_intr+0x0/0x16
DWARF2 unwinder stuck at ret_from_intr+0x0/0x16
Leftover inexact backtrace:
<IRQ <EOI [<ffffffff802b6627 ] ? __rcu_read_lock+0xae/0xbc
[<ffffffff804ee0ec ] ? __atomic_notifier_call_chain+0x2c/0x56
[<ffffffff804ee125 ] ? atomic_notifier_call_chain+0xf/0x11
[<ffffffff80224121 ] ? cpu_idle+0x7d/0xca
[<ffffffff804e427f ] ? start_secondary+0xc5/0xca
Signed-off-by: Jan Blunck <jblunck@xxxxxxx
---
kernel/irq/handle.c | 38 ++++++++++++++++++++++++++------------
kernel/irq/internals.h | 2 +-
kernel/irq/numa_migrate.c | 38 +++++++++++++++++++++-----------------
kernel/softirq.c | 6 ++++++
4 files changed, 54 insertions(+), 30 deletions(-)
Index: b/kernel/irq/handle.c
===================================================================
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -124,10 +124,17 @@ static void init_one_irq_desc(int irq, s
arch_init_chip_data(desc, cpu);
}
+static void free_one_irq_desc(struct irq_desc *desc)
+{
+ kfree(desc- kstat_irqs);
+ desc- kstat_irqs = NULL;
+ arch_free_chip_data(desc, &irq_desc_init);
+}
+
/*
* Protect the sparse_irqs:
*/
-DEFINE_SPINLOCK(sparse_irq_lock);
+DEFINE_RAW_SPINLOCK(sparse_irq_lock);
struct irq_desc **irq_desc_ptrs __read_mostly;
@@ -191,7 +198,7 @@ struct irq_desc *irq_to_desc(unsigned in
struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
{
- struct irq_desc *desc;
+ struct irq_desc *desc, *tmp;
unsigned long flags;
int node;
@@ -205,6 +212,17 @@ struct irq_desc *irq_to_desc_alloc_cpu(u
if (desc)
return desc;
+ /* Allocate memory before disabling interrupts */
+ node = cpu_to_node(cpu);
+ tmp = kzalloc_node(sizeof(*tmp), GFP_ATOMIC, node);
+ printk(KERN_DEBUG " alloc irq_desc for %d on cpu %d node %d
",
+ irq, cpu, node);
+ if (!tmp) {
+ printk(KERN_ERR "can not alloc irq_desc
");
+ BUG_ON(1);
+ }
+ init_one_irq_desc(irq, tmp, cpu);
+
spin_lock_irqsave(&sparse_irq_lock, flags);
/* We have to check it to avoid races with another CPU */
@@ -212,20 +230,16 @@ struct irq_desc *irq_to_desc_alloc_cpu(u
if (desc)
goto out_unlock;
- node = cpu_to_node(cpu);
- desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
- printk(KERN_DEBUG " alloc irq_desc for %d on cpu %d node %d
",
- irq, cpu, node);
- if (!desc) {
- printk(KERN_ERR "can not alloc irq_desc
");
- BUG_ON(1);
- }
- init_one_irq_desc(irq, desc, cpu);
+ irq_desc_ptrs[irq] = tmp;
+ desc = tmp;
+ spin_unlock_irqrestore(&sparse_irq_lock, flags);
- irq_desc_ptrs[irq] = desc;
+ return desc;
out_unlock:
spin_unlock_irqrestore(&sparse_irq_lock, flags);
+ free_one_irq_desc(tmp);
+ kfree(tmp);
return desc;
}
Index: b/kernel/irq/internals.h
===================================================================
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -16,7 +16,7 @@ extern int __irq_set_trigger(struct irq_
extern struct lock_class_key irq_desc_lock_class;
extern void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr);
extern void clear_kstat_irqs(struct irq_desc *desc);
-extern spinlock_t sparse_irq_lock;
+extern raw_spinlock_t sparse_irq_lock;
#ifdef CONFIG_SPARSE_IRQ
/* irq_desc_ptrs allocated at boot time */
Index: b/kernel/irq/numa_migrate.c
===================================================================
--- a/kernel/irq/numa_migrate.c
+++ b/kernel/irq/numa_migrate.c
@@ -61,38 +61,40 @@ static void free_one_irq_desc(struct irq
static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc,
int cpu)
{
- struct irq_desc *desc;
+ struct irq_desc *desc, *tmp;
unsigned int irq;
unsigned long flags;
int node;
irq = old_desc- irq;
- spin_lock_irqsave(&sparse_irq_lock, flags);
-
- /* We have to check it to avoid races with another CPU */
- desc = irq_desc_ptrs[irq];
-
- if (desc && old_desc != desc)
- goto out_unlock;
-
+ /* Allocate memory before disabling IRQs */
node = cpu_to_node(cpu);
- desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
- if (!desc) {
+ tmp = kzalloc_node(sizeof(*tmp), GFP_ATOMIC, node);
+ if (!tmp) {
printk(KERN_ERR "irq %d: can not get new irq_desc "
"for migration.
", irq);
/* still use old one */
desc = old_desc;
- goto out_unlock;
+ goto out;
}
- if (!init_copy_one_irq_desc(irq, old_desc, desc, cpu)) {
+ if (!init_copy_one_irq_desc(irq, old_desc, tmp, cpu)) {
/* still use old one */
- kfree(desc);
+ kfree(tmp);
desc = old_desc;
- goto out_unlock;
+ goto out;
}
- irq_desc_ptrs[irq] = desc;
+ spin_lock_irqsave(&sparse_irq_lock, flags);
+
+ /* We have to check it to avoid races with another CPU */
+ desc = irq_desc_ptrs[irq];
+
+ if (desc && old_desc != desc)
+ goto out_unlock;
+
+ irq_desc_ptrs[irq] = tmp;
+ desc = tmp;
spin_unlock_irqrestore(&sparse_irq_lock, flags);
/* free the old one */
@@ -105,7 +107,9 @@ static struct irq_desc *__real_move_irq_
out_unlock:
spin_unlock_irqrestore(&sparse_irq_lock, flags);
-
+ free_one_irq_desc(tmp, old_desc);
+ kfree(tmp);
+out:
return desc;
}
Index: b/kernel/softirq.c
===================================================================
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -1202,3 +1202,9 @@ int __weak arch_init_chip_data(struct ir
{
return 0;
}
+
+void __weak arch_free_chip_data(struct irq_desc *old_desc,
+ struct irq_desc *desc)
+{
+ return;
+}
--
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