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irqchip: gicv3-its: Fix unsafe locking reported by lockdep 

When compiled with CONFIG_LOCKDEP, the kernel shouts badly, saying
that my locking is unsafe. I'm afraid the kernel is right:

       CPU0                    CPU1
       ----                    ----
  lock(&its->lock);
                               local_irq_disable();
                               lock(&irq_desc_lock_class);
                               lock(&its->lock);
  <Interrupt>
    lock(&irq_desc_lock_class);

 *** DEADLOCK ***

The fix is to always take its->lock with interrupts disabled.

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1425659870-11832-5-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
hifive-unleashed-5.1
Marc Zyngier 2015-03-06 16:37:43 +00:00 committed by Jason Cooper
parent e8137f4f50
commit 3e39e8f56c
1 changed files with 14 additions and 9 deletions
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23
drivers/irqchip/irq-gic-v3-its.c
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@ -416,13 +416,14 @@ static void its_send_single_command(struct its_node *its,
{
struct its_cmd_block *cmd, *sync_cmd, *next_cmd;
struct its_collection *sync_col;
unsigned long flags;
raw_spin_lock(&its->lock);
raw_spin_lock_irqsave(&its->lock, flags);
cmd = its_allocate_entry(its);
if (!cmd) { /* We're soooooo screewed... */
pr_err_ratelimited("ITS can't allocate, dropping command\n");
raw_spin_unlock(&its->lock);
raw_spin_unlock_irqrestore(&its->lock, flags);
return;
}
sync_col = builder(cmd, desc);
@ -442,7 +443,7 @@ static void its_send_single_command(struct its_node *its,
post:
next_cmd = its_post_commands(its);
raw_spin_unlock(&its->lock);
raw_spin_unlock_irqrestore(&its->lock, flags);
its_wait_for_range_completion(its, cmd, next_cmd);
}
@ -1037,8 +1038,9 @@ static void its_cpu_init_collection(void)
static struct its_device *its_find_device(struct its_node *its, u32 dev_id)
{
struct its_device *its_dev = NULL, *tmp;
unsigned long flags;
raw_spin_lock(&its->lock);
raw_spin_lock_irqsave(&its->lock, flags);
list_for_each_entry(tmp, &its->its_device_list, entry) {
if (tmp->device_id == dev_id) {
@ -1047,7 +1049,7 @@ static struct its_device *its_find_device(struct its_node *its, u32 dev_id)
}
}
raw_spin_unlock(&its->lock);
raw_spin_unlock_irqrestore(&its->lock, flags);
return its_dev;
}
@ -1057,6 +1059,7 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
{
struct its_device *dev;
unsigned long *lpi_map;
unsigned long flags;
void *itt;
int lpi_base;
int nr_lpis;
@ -1092,9 +1095,9 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
dev->device_id = dev_id;
INIT_LIST_HEAD(&dev->entry);
raw_spin_lock(&its->lock);
raw_spin_lock_irqsave(&its->lock, flags);
list_add(&dev->entry, &its->its_device_list);
raw_spin_unlock(&its->lock);
raw_spin_unlock_irqrestore(&its->lock, flags);
/* Bind the device to the first possible CPU */
cpu = cpumask_first(cpu_online_mask);
@ -1108,9 +1111,11 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
static void its_free_device(struct its_device *its_dev)
{
raw_spin_lock(&its_dev->its->lock);
unsigned long flags;
raw_spin_lock_irqsave(&its_dev->its->lock, flags);
list_del(&its_dev->entry);
raw_spin_unlock(&its_dev->its->lock);
raw_spin_unlock_irqrestore(&its_dev->its->lock, flags);
kfree(its_dev->itt);
kfree(its_dev);
}