Commit 5edf71ae authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[ARM] Do not call flush_tlb_kernel_range() with IRQs disabled. 



We must not call TLB maintainence operations with interrupts disabled,
otherwise we risk a lockup in the SMP IPI code.

This means that consistent_free() can not be called from a context with
IRQs disabled.  In addition, we must not hold the lock in consistent_free
when we call flush_tlb_kernel_range().  However, we must continue to
prevent consistent_alloc() from re-using the memory region until we've
finished tearing down the mapping and dealing with the TLB.

Therefore, leave the vm_region entry in the list, but mark it inactive
before dropping the lock and starting the tear-down process.  After the
mapping has been torn down, re-acquire the lock and remove the entry
from the list.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 3c0bdac3

arch/arm/mm/consistent.c

+10 −3
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ struct vm_region { 
	unsigned long		vm_start;

	unsigned long		vm_end;

	struct page		*vm_pages;

	int			vm_active;

};



static struct vm_region consistent_head = {
@@ -104,6 +105,7 @@ vm_region_alloc(struct vm_region *head, size_t size, gfp_t gfp) 
	list_add_tail(&new->vm_list, &c->vm_list);

	new->vm_start = addr;

	new->vm_end = addr + size;

	new->vm_active = 1;



	spin_unlock_irqrestore(&consistent_lock, flags);

	return new;
@@ -120,7 +122,7 @@ static struct vm_region *vm_region_find(struct vm_region *head, unsigned long ad 
	struct vm_region *c;

	

	list_for_each_entry(c, &head->vm_list, vm_list) {

		if (c->vm_start == addr)

		if (c->vm_active && c->vm_start == addr)

			goto out;

	}

	c = NULL;
@@ -319,6 +321,7 @@ EXPORT_SYMBOL(dma_mmap_writecombine); 


/*

 * free a page as defined by the above mapping.

 * Must not be called with IRQs disabled.

 */

void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)

{
@@ -326,14 +329,18 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr 
	unsigned long flags, addr;

	pte_t *ptep;



	WARN_ON(irqs_disabled());



	size = PAGE_ALIGN(size);



	spin_lock_irqsave(&consistent_lock, flags);



	c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);

	if (!c)

		goto no_area;



	c->vm_active = 0;

	spin_unlock_irqrestore(&consistent_lock, flags);



	if ((c->vm_end - c->vm_start) != size) {

		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",

		       __func__, c->vm_end - c->vm_start, size);
@@ -372,8 +379,8 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr 


	flush_tlb_kernel_range(c->vm_start, c->vm_end);



	spin_lock_irqsave(&consistent_lock, flags);

	list_del(&c->vm_list);



	spin_unlock_irqrestore(&consistent_lock, flags);



	kfree(c);

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