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exec: always call qemu_get_ram_ptr within rcu_read_lock

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Simplify the code and document the assumption.  The only caller
that is not within rcu_read_lock is memory_region_get_ram_ptr.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2015-12-16 10:30:47 +01:00
parent c8ee0a445a
commit 49b24afcb1
3 changed files with 22 additions and 23 deletions
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22
exec.c
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@ -1786,19 +1786,11 @@ void *qemu_get_ram_block_host_ptr(ram_addr_t addr)
* or address_space_rw instead. For local memory (e.g. video ram) that the
* device owns, use memory_region_get_ram_ptr.
*
* By the time this function returns, the returned pointer is not protected
* by RCU anymore. If the caller is not within an RCU critical section and
* does not hold the iothread lock, it must have other means of protecting the
* pointer, such as a reference to the region that includes the incoming
* ram_addr_t.
* Called within RCU critical section.
*/
void *qemu_get_ram_ptr(ram_addr_t addr)
{
RAMBlock *block;
void *ptr;
rcu_read_lock();
block = qemu_get_ram_block(addr);
RAMBlock *block = qemu_get_ram_block(addr);
if (xen_enabled() && block->host == NULL) {
/* We need to check if the requested address is in the RAM
@ -1806,17 +1798,12 @@ void *qemu_get_ram_ptr(ram_addr_t addr)
* In that case just map until the end of the page.
*/
if (block->offset == 0) {
ptr = xen_map_cache(addr, 0, 0);
goto unlock;
return xen_map_cache(addr, 0, 0);
}
block->host = xen_map_cache(block->offset, block->max_length, 1);
}
ptr = ramblock_ptr(block, addr - block->offset);
unlock:
rcu_read_unlock();
return ptr;
return ramblock_ptr(block, addr - block->offset);
}
/* Return a host pointer to guest's ram. Similar to qemu_get_ram_ptr
@ -1954,6 +1941,7 @@ MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
return block->mr;
}
/* Called within RCU critical section. */
static void notdirty_mem_write(void *opaque, hwaddr ram_addr,
uint64_t val, unsigned size)
{