[PATCH AUTOSEL 5.0 083/262] ARM: 8840/1: use a raw_spinlock_t in unwind

Sasha Levin
2019-03-27T18:04:42Z

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

[ Upstream commit 74ffe79ae538283bbf7c155e62339f1e5c87b55a ]

Mostly unwind is done with irqs enabled however SLUB may call it with
irqs disabled while creating a new SLUB cache.

I had system freeze while loading a module which called
kmem_cache_create() on init. That means SLUB's __slab_alloc() disabled
interrupts and then

->new_slab_objects()
->new_slab()
->setup_object()
->setup_object_debug()
->init_tracking()
->set_track()
->save_stack_trace()
->save_stack_trace_tsk()
->walk_stackframe()
->unwind_frame()
->unwind_find_idx()
=>spin_lock_irqsave(&unwind_lock);

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/kernel/unwind.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 0bee233fef9a..314cfb232a63 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -93,7 +93,7 @@ extern const struct unwind_idx __start_unwind_idx[];
static const struct unwind_idx *__origin_unwind_idx;
extern const struct unwind_idx __stop_unwind_idx[];

-static DEFINE_SPINLOCK(unwind_lock);
+static DEFINE_RAW_SPINLOCK(unwind_lock);
static LIST_HEAD(unwind_tables);

/* Convert a prel31 symbol to an absolute address */
@@ -201,7 +201,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr)
/* module unwind tables */
struct unwind_table *table;

- spin_lock_irqsave(&unwind_lock, flags);
+ raw_spin_lock_irqsave(&unwind_lock, flags);
list_for_each_entry(table, &unwind_tables, list) {
if (addr >= table->begin_addr &&
addr < table->end_addr) {
@@ -213,7 +213,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr)
break;
}
}
- spin_unlock_irqrestore(&unwind_lock, flags);
+ raw_spin_unlock_irqrestore(&unwind_lock, flags);
}

pr_debug("%s: idx = %p\n", __func__, idx);
@@ -529,9 +529,9 @@ struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
tab->begin_addr = text_addr;
tab->end_addr = text_addr + text_size;

- spin_lock_irqsave(&unwind_lock, flags);
+ raw_spin_lock_irqsave(&unwind_lock, flags);
list_add_tail(&tab->list, &unwind_tables);
- spin_unlock_irqrestore(&unwind_lock, flags);
+ raw_spin_unlock_irqrestore(&unwind_lock, flags);

return tab;
}
@@ -543,9 +543,9 @@ void unwind_table_del(struct unwind_table *tab)
if (!tab)
return;

- spin_lock_irqsave(&unwind_lock, flags);
+ raw_spin_lock_irqsave(&unwind_lock, flags);
list_del(&tab->list);
- spin_unlock_irqrestore(&unwind_lock, flags);
+ raw_spin_unlock_irqrestore(&unwind_lock, flags);

kfree(tab);
}
--
2.19.1