Re: [git pull] sparseirq / irq updates for v2.6.29

Ingo Molnar
2008-12-28T23:28:13Z

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Sat, 27 Dec 2008, Ingo Molnar wrote:
> >
> > well, it's a regression that is being worked on: certain buggy GCC
> > versions (unclear yet what scope but quite rare it appears) optimize
> > out __weak function calls incorrectly.
>
> We've hit that kind of bug before, haven't we? I think the solution last
> time was to make sure that the __weak function is never in the same
> compilation unit as a call to it.

ok, agreed. I was hoping for some more generic workaround but nothing
seemed to keep gcc from inlining such functions.

Here's the irq-fixes-for-linus-3 that has this fixed, via:

b2e2fe9: sparseirq: work around __weak alias bug

which moves the weak arch_init_chip_data() alias from handle.c to
manage.c. Please pull the fix from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git irq-fixes-for-linus-3

[ the shortlog is relative to irq-core-for-linus. The other URIs i sent
are also valid and can be pulled in arbitrary order. ]

Thanks,

Ingo

------------------>
Ingo Molnar (3):
sparseirq: do not printk when migrating IRQ descriptors
sparseirq: fix desc->lock init
sparseirq: work around __weak alias bug

KOSAKI Motohiro (4):
hrtimer: remove #include <linux/irq.h>
irq: for_each_irq_desc() move to irqnr.h
proc: remove ifdef CONFIG_SPARSE_IRQ from stat.c
irq: simplify for_each_irq_desc() usage

Yinghai Lu (4):
sparseirq: remove duplicated arch_early_irq_init()
sparseirq: work around compiler optimizing away __weak functions
sparseirq: set lock_class for legacy irq when sparse_irq is selected
sparseirq: fix hang with !SPARSE_IRQ

arch/x86/kernel/io_apic.c | 18 +++++-----------
drivers/xen/events.c | 3 --
fs/proc/stat.c | 11 +---------
include/linux/irq.h | 30 ++++++---------------------
include/linux/irqnr.h | 23 ++++++++++++---------
init/main.c | 7 +++--
kernel/hrtimer.c | 1 -
kernel/irq/autoprobe.c | 15 --------------
kernel/irq/handle.c | 48 ++++++++++++++++++++++++++++++---------------
kernel/irq/manage.c | 9 ++++++++
kernel/irq/numa_migrate.c | 7 +----
kernel/irq/spurious.c | 5 ----
12 files changed, 74 insertions(+), 103 deletions(-)

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index a74887b..9760393 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -170,7 +170,7 @@ static struct irq_cfg irq_cfgx[NR_IRQS] = {
[15] = { .domain = CPU_MASK_ALL, .vector = IRQ15_VECTOR, },
};

-void __init arch_early_irq_init(void)
+int __init arch_early_irq_init(void)
{
struct irq_cfg *cfg;
struct irq_desc *desc;
@@ -184,6 +184,8 @@ void __init arch_early_irq_init(void)
desc = irq_to_desc(i);
desc->chip_data = &cfg[i];
}
+
+ return 0;
}

#ifdef CONFIG_SPARSE_IRQ
@@ -212,7 +214,7 @@ static struct irq_cfg *get_one_free_irq_cfg(int cpu)
return cfg;
}

-void arch_init_chip_data(struct irq_desc *desc, int cpu)
+int arch_init_chip_data(struct irq_desc *desc, int cpu)
{
struct irq_cfg *cfg;

@@ -224,6 +226,8 @@ void arch_init_chip_data(struct irq_desc *desc, int cpu)
BUG_ON(1);
}
}
+
+ return 0;
}

#ifdef CONFIG_NUMA_MIGRATE_IRQ_DESC
@@ -1345,8 +1349,6 @@ void __setup_vector_irq(int cpu)

/* Mark the inuse vectors */
for_each_irq_desc(irq, desc) {
- if (!desc)
- continue;
cfg = desc->chip_data;
if (!cpu_isset(cpu, cfg->domain))
continue;
@@ -1730,8 +1732,6 @@ __apicdebuginit(void) print_IO_APIC(void)
for_each_irq_desc(irq, desc) {
struct irq_pin_list *entry;

- if (!desc)
- continue;
cfg = desc->chip_data;
entry = cfg->irq_2_pin;
if (!entry)
@@ -2378,9 +2378,6 @@ static void ir_irq_migration(struct work_struct *work)
struct irq_desc *desc;

for_each_irq_desc(irq, desc) {
- if (!desc)
- continue;
-
if (desc->status & IRQ_MOVE_PENDING) {
unsigned long flags;

@@ -2671,9 +2668,6 @@ static inline void init_IO_APIC_traps(void)
* 0x80, because int 0x80 is hm, kind of importantish. ;)
*/
for_each_irq_desc(irq, desc) {
- if (!desc)
- continue;
-
cfg = desc->chip_data;
if (IO_APIC_IRQ(irq) && cfg && !cfg->vector) {
/*
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 46625cd..e26733a 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -142,9 +142,6 @@ static void init_evtchn_cpu_bindings(void)

/* By default all event channels notify CPU#0. */
for_each_irq_desc(i, desc) {
- if (!desc)
- continue;
-
desc->affinity = cpumask_of_cpu(0);
}
#endif
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 3bb1cf1..f75efa2 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -9,6 +9,7 @@
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/time.h>
+#include <linux/irqnr.h>
#include <asm/cputime.h>

#ifndef arch_irq_stat_cpu
@@ -45,10 +46,6 @@ static int show_stat(struct seq_file *p, void *v)
steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
for_each_irq_nr(j) {
-#ifdef CONFIG_SPARSE_IRQ
- if (!irq_to_desc(j))
- continue;
-#endif
sum += kstat_irqs_cpu(j, i);
}
sum += arch_irq_stat_cpu(i);
@@ -95,12 +92,6 @@ static int show_stat(struct seq_file *p, void *v)
/* sum again ? it could be updated? */
for_each_irq_nr(j) {
per_irq_sum = 0;
-#ifdef CONFIG_SPARSE_IRQ
- if (!irq_to_desc(j)) {
- seq_printf(p, " %u", per_irq_sum);
- continue;
- }
-#endif
for_each_possible_cpu(i)
per_irq_sum += kstat_irqs_cpu(j, i);

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 98564dc..0e40af4 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -193,42 +193,26 @@ struct irq_desc {
const char *name;
} ____cacheline_internodealigned_in_smp;

-extern void early_irq_init(void);
-extern void arch_early_irq_init(void);
-extern void arch_init_chip_data(struct irq_desc *desc, int cpu);
+extern int early_irq_init(void);
+extern int arch_early_irq_init(void);
+extern int arch_init_chip_data(struct irq_desc *desc, int cpu);
extern void arch_init_copy_chip_data(struct irq_desc *old_desc,
struct irq_desc *desc, int cpu);
extern void arch_free_chip_data(struct irq_desc *old_desc, struct irq_desc *desc);

#ifndef CONFIG_SPARSE_IRQ
extern struct irq_desc irq_desc[NR_IRQS];
-
-static inline struct irq_desc *irq_to_desc(unsigned int irq)
-{
- return (irq < NR_IRQS) ? irq_desc + irq : NULL;
-}
-static inline struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
-{
- return irq_to_desc(irq);
-}
-
-#else
-
-extern struct irq_desc *irq_to_desc(unsigned int irq);
-extern struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu);
+#else /* CONFIG_SPARSE_IRQ */
extern struct irq_desc *move_irq_desc(struct irq_desc *old_desc, int cpu);

-# define for_each_irq_desc(irq, desc) \
- for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs; irq++, desc = irq_to_desc(irq))
-# define for_each_irq_desc_reverse(irq, desc) \
- for (irq = nr_irqs - 1, desc = irq_to_desc(irq); irq >= 0; irq--, desc = irq_to_desc(irq))
-
#define kstat_irqs_this_cpu(DESC) \
((DESC)->kstat_irqs[smp_processor_id()])
#define kstat_incr_irqs_this_cpu(irqno, DESC) \
((DESC)->kstat_irqs[smp_processor_id()]++)

-#endif
+#endif /* CONFIG_SPARSE_IRQ */
+
+extern struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu);

static inline struct irq_desc *
irq_remap_to_desc(unsigned int irq, struct irq_desc *desc)
diff --git a/include/linux/irqnr.h b/include/linux/irqnr.h
index 95d2b74..5504a5c 100644
--- a/include/linux/irqnr.h
+++ b/include/linux/irqnr.h
@@ -15,20 +15,23 @@

# define for_each_irq_desc_reverse(irq, desc) \
for (irq = nr_irqs - 1; irq >= 0; irq--)
-#else
+#else /* CONFIG_GENERIC_HARDIRQS */

extern int nr_irqs;
+extern struct irq_desc *irq_to_desc(unsigned int irq);

-#ifndef CONFIG_SPARSE_IRQ
+# define for_each_irq_desc(irq, desc) \
+ for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs; \
+ irq++, desc = irq_to_desc(irq)) \
+ if (desc)

-struct irq_desc;
-# define for_each_irq_desc(irq, desc) \
- for (irq = 0, desc = irq_desc; irq < nr_irqs; irq++, desc++)
-# define for_each_irq_desc_reverse(irq, desc) \
- for (irq = nr_irqs - 1, desc = irq_desc + (nr_irqs - 1); \
- irq >= 0; irq--, desc--)
-#endif
-#endif
+
+# define for_each_irq_desc_reverse(irq, desc) \
+ for (irq = nr_irqs - 1, desc = irq_to_desc(irq); irq >= 0; \
+ irq--, desc = irq_to_desc(irq)) \
+ if (desc)
+
+#endif /* CONFIG_GENERIC_HARDIRQS */

#define for_each_irq_nr(irq) \
for (irq = 0; irq < nr_irqs; irq++)
diff --git a/init/main.c b/init/main.c
index c1f999a..c314aa1 100644
--- a/init/main.c
+++ b/init/main.c
@@ -539,13 +539,14 @@ void __init __weak thread_info_cache_init(void)
{
}

-void __init __weak arch_early_irq_init(void)
+int __init __weak arch_early_irq_init(void)
{
+ return 0;
}

-void __init __weak early_irq_init(void)
+int __init __weak early_irq_init(void)
{
- arch_early_irq_init();
+ return arch_early_irq_init();
}

asmlinkage void __init start_kernel(void)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 47e6334..0ad3f3d 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -32,7 +32,6 @@
*/

#include <linux/cpu.h>
-#include <linux/irq.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
diff --git a/kernel/irq/autoprobe.c b/kernel/irq/autoprobe.c
index 650ce41..cc0f732 100644
--- a/kernel/irq/autoprobe.c
+++ b/kernel/irq/autoprobe.c
@@ -40,9 +40,6 @@ unsigned long probe_irq_on(void)
* flush such a longstanding irq before considering it as spurious.
*/
for_each_irq_desc_reverse(i, desc) {
- if (!desc)
- continue;
-
spin_lock_irq(&desc->lock);
if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
/*
@@ -71,9 +68,6 @@ unsigned long probe_irq_on(void)
* happened in the previous stage, it may have masked itself)
*/
for_each_irq_desc_reverse(i, desc) {
- if (!desc)
- continue;
-
spin_lock_irq(&desc->lock);
if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
@@ -92,9 +86,6 @@ unsigned long probe_irq_on(void)
* Now filter out any obviously spurious interrupts
*/
for_each_irq_desc(i, desc) {
- if (!desc)
- continue;
-
spin_lock_irq(&desc->lock);
status = desc->status;

@@ -133,9 +124,6 @@ unsigned int probe_irq_mask(unsigned long val)
int i;

for_each_irq_desc(i, desc) {
- if (!desc)
- continue;
-
spin_lock_irq(&desc->lock);
status = desc->status;

@@ -178,9 +166,6 @@ int probe_irq_off(unsigned long val)
unsigned int status;

for_each_irq_desc(i, desc) {
- if (!desc)
- continue;
-
spin_lock_irq(&desc->lock);
status = desc->status;

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 6492400..c20db0b 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -56,10 +56,6 @@ void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);

-void __init __attribute__((weak)) arch_early_irq_init(void)
-{
-}
-
#ifdef CONFIG_SPARSE_IRQ
static struct irq_desc irq_desc_init = {
.irq = -1,
@@ -90,13 +86,11 @@ void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
desc->kstat_irqs = (unsigned int *)ptr;
}

-void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu)
-{
-}
-
static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
{
memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));
+
+ spin_lock_init(&desc->lock);
desc->irq = irq;
#ifdef CONFIG_SMP
desc->cpu = cpu;
@@ -134,7 +128,7 @@ static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_sm
/* FIXME: use bootmem alloc ...*/
static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];

-void __init early_irq_init(void)
+int __init early_irq_init(void)
{
struct irq_desc *desc;
int legacy_count;
@@ -146,6 +140,7 @@ void __init early_irq_init(void)
for (i = 0; i < legacy_count; i++) {
desc[i].irq = i;
desc[i].kstat_irqs = kstat_irqs_legacy[i];
+ lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);

irq_desc_ptrs[i] = desc + i;
}
@@ -153,7 +148,7 @@ void __init early_irq_init(void)
for (i = legacy_count; i < NR_IRQS; i++)
irq_desc_ptrs[i] = NULL;

- arch_early_irq_init();
+ return arch_early_irq_init();
}

struct irq_desc *irq_to_desc(unsigned int irq)
@@ -203,7 +198,7 @@ out_unlock:
return desc;
}

-#else
+#else /* !CONFIG_SPARSE_IRQ */

struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS-1] = {
@@ -218,7 +213,31 @@ struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
}
};

-#endif
+int __init early_irq_init(void)
+{
+ struct irq_desc *desc;
+ int count;
+ int i;
+
+ desc = irq_desc;
+ count = ARRAY_SIZE(irq_desc);
+
+ for (i = 0; i < count; i++)
+ desc[i].irq = i;
+
+ return arch_early_irq_init();
+}
+
+struct irq_desc *irq_to_desc(unsigned int irq)
+{
+ return (irq < NR_IRQS) ? irq_desc + irq : NULL;
+}
+
+struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
+{
+ return irq_to_desc(irq);
+}
+#endif /* !CONFIG_SPARSE_IRQ */

/*
* What should we do if we get a hw irq event on an illegal vector?
@@ -428,9 +447,6 @@ void early_init_irq_lock_class(void)
int i;

for_each_irq_desc(i, desc) {
- if (!desc)
- continue;
-
lockdep_set_class(&desc->lock, &irq_desc_lock_class);
}
}
@@ -439,7 +455,7 @@ void early_init_irq_lock_class(void)
unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
struct irq_desc *desc = irq_to_desc(irq);
- return desc->kstat_irqs[cpu];
+ return desc ? desc->kstat_irqs[cpu] : 0;
}
#endif
EXPORT_SYMBOL(kstat_irqs_cpu);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 46953a0..c2741b0 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -261,6 +261,15 @@ void enable_irq(unsigned int irq)
}
EXPORT_SYMBOL(enable_irq);

+/*
+ * [ Not in kernel/irq/handle.c, so that GCC does not
+ * inline the __weak alias: ]
+ */
+int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
+{
+ return 0;
+}
+
static int set_irq_wake_real(unsigned int irq, unsigned int on)
{
struct irq_desc *desc = irq_to_desc(irq);
diff --git a/kernel/irq/numa_migrate.c b/kernel/irq/numa_migrate.c
index 089c374..ecf765c 100644
--- a/kernel/irq/numa_migrate.c
+++ b/kernel/irq/numa_migrate.c
@@ -42,6 +42,7 @@ static void init_copy_one_irq_desc(int irq, struct irq_desc *old_desc,
struct irq_desc *desc, int cpu)
{
memcpy(desc, old_desc, sizeof(struct irq_desc));
+ spin_lock_init(&desc->lock);
desc->cpu = cpu;
lockdep_set_class(&desc->lock, &irq_desc_lock_class);
init_copy_kstat_irqs(old_desc, desc, cpu, nr_cpu_ids);
@@ -74,10 +75,8 @@ static struct irq_desc *__real_move_irq_desc(struct irq_desc *old_desc,

node = cpu_to_node(cpu);
desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
- printk(KERN_DEBUG " move irq_desc for %d to cpu %d node %d\n",
- irq, cpu, node);
if (!desc) {
- printk(KERN_ERR "can not get new irq_desc for moving\n");
+ printk(KERN_ERR "irq %d: can not get new irq_desc for migration.\n", irq);
/* still use old one */
desc = old_desc;
goto out_unlock;
@@ -106,8 +105,6 @@ struct irq_desc *move_irq_desc(struct irq_desc *desc, int cpu)
return desc;

old_cpu = desc->cpu;
- printk(KERN_DEBUG
- "try to move irq_desc from cpu %d to %d\n", old_cpu, cpu);
if (old_cpu != cpu) {
node = cpu_to_node(cpu);
old_node = cpu_to_node(old_cpu);
diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index 3738107..dd364c1 100644
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -91,9 +91,6 @@ static int misrouted_irq(int irq)
int i, ok = 0;

for_each_irq_desc(i, desc) {
- if (!desc)
- continue;
-
if (!i)
continue;

@@ -115,8 +112,6 @@ static void poll_spurious_irqs(unsigned long dummy)
for_each_irq_desc(i, desc) {
unsigned int status;

- if (!desc)
- continue;
if (!i)
continue;