lkml.org 
[lkml]   [2008]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] x86: sparse_irq need spin_lock in alloc

* Ingo Molnar <mingo@elte.hu> wrote:

> * Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > Each of these locks can be made local to the function in which they
> > are used (and hence they should be made local).
> >
> > It would be nice to add a comment explaining what they are protecting,
> > unless that is obvious (I didn't look).
>
> ok - i moved the locks next to the data structure they protect (the free
> list head), and added a small exlanation as well - as per the commit
> below.

they also need to be irqsafe locks, as they might be taken inside
irq-safe locks. Updated patch below.

Ingo

From a532e19680ada3b8579b81e67e76d3ebd19c340f Mon Sep 17 00:00:00 2001
From: Yinghai Lu <yhlu.kernel@gmail.com>
Date: Wed, 20 Aug 2008 20:46:25 -0700
Subject: [PATCH] x86: sparse_irq needs spin_lock in allocations

Suresh Siddha noticed that we should have a spinlock around it.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/io_apic.c | 13 ++++++++++++-
kernel/irq/handle.c | 13 ++++++++++++-
2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 34c74cf..7ca5566 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -146,6 +146,12 @@ static void init_one_irq_cfg(struct irq_cfg *cfg)
}

static struct irq_cfg *irq_cfgx;
+
+/*
+ * Protect the irq_cfgx_free freelist:
+ */
+static DEFINE_SPINLOCK(irq_cfg_lock);
+
#ifdef CONFIG_HAVE_SPARSE_IRQ
static struct irq_cfg *irq_cfgx_free;
#endif
@@ -213,8 +219,9 @@ static struct irq_cfg *irq_cfg(unsigned int irq)
static struct irq_cfg *irq_cfg_alloc(unsigned int irq)
{
struct irq_cfg *cfg, *cfg_pri;
- int i;
+ unsigned long flags;
int count = 0;
+ int i;

cfg_pri = cfg = irq_cfgx;
while (cfg) {
@@ -226,6 +233,7 @@ static struct irq_cfg *irq_cfg_alloc(unsigned int irq)
count++;
}

+ spin_lock_irqsave(&irq_cfg_lock, flags);
if (!irq_cfgx_free) {
unsigned long phys;
unsigned long total_bytes;
@@ -263,6 +271,9 @@ static struct irq_cfg *irq_cfg_alloc(unsigned int irq)
else
irq_cfgx = cfg;
cfg->irq = irq;
+
+ spin_unlock_irqrestore(&irq_cfg_lock, flags);
+
printk(KERN_DEBUG "found new irq_cfg for irq %d\n", cfg->irq);
#ifdef CONFIG_HAVE_SPARSE_IRQ_DEBUG
{
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 24c83a3..d638a91 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -107,6 +107,11 @@ static void init_kstat_irqs(struct irq_desc *desc, int nr_desc, int nr)
}
}

+/*
+ * Protect the sparse_irqs_free freelist:
+ */
+static DEFINE_SPINLOCK(sparse_irq_lock);
+
#ifdef CONFIG_HAVE_SPARSE_IRQ
static struct irq_desc *sparse_irqs_free;
struct irq_desc *sparse_irqs;
@@ -166,11 +171,13 @@ struct irq_desc *irq_to_desc(unsigned int irq)
}
return NULL;
}
+
struct irq_desc *irq_to_desc_alloc(unsigned int irq)
{
struct irq_desc *desc, *desc_pri;
- int i;
+ unsigned long flags;
int count = 0;
+ int i;

desc_pri = desc = sparse_irqs;
while (desc) {
@@ -182,6 +189,7 @@ struct irq_desc *irq_to_desc_alloc(unsigned int irq)
count++;
}

+ spin_lock_irqsave(&sparse_irq_lock, flags);
/*
* we run out of pre-allocate ones, allocate more
*/
@@ -223,6 +231,9 @@ struct irq_desc *irq_to_desc_alloc(unsigned int irq)
else
sparse_irqs = desc;
desc->irq = irq;
+
+ spin_unlock_irqrestore(&sparse_irq_lock, flags);
+
printk(KERN_DEBUG "found new irq_desc for irq %d\n", desc->irq);
#ifdef CONFIG_HAVE_SPARSE_IRQ_DEBUG
{

\
 
 \ /
  Last update: 2008-08-21 12:31    [W:0.053 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site