From 49b24afcb11d682d82747f706e3bd6174fe84062 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 16 Dec 2015 10:30:47 +0100 Subject: exec: always call qemu_get_ram_ptr within rcu_read_lock 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 --- exec.c | 22 +++++----------------- 1 file changed, 5 insertions(+), 17 deletions(-) (limited to 'exec.c') diff --git a/exec.c b/exec.c index dd11ef9e34..af954388f5 100644 --- a/exec.c +++ b/exec.c @@ -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) { -- cgit v1.2.3