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[Qemu-devel] [PULL 02/22] exec: Atomic access to bounce buffer
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 02/22] exec: Atomic access to bounce buffer |
Date: |
Tue, 28 Apr 2015 16:40:09 +0200 |
From: Fam Zheng <address@hidden>
There could be a race condition when two processes call
address_space_map concurrently and both want to use the bounce buffer.
Add an in_use flag in BounceBuffer to sync it.
Signed-off-by: Fam Zheng <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
exec.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index 874ecfc..5a1c700 100644
--- a/exec.c
+++ b/exec.c
@@ -2482,6 +2482,7 @@ typedef struct {
void *buffer;
hwaddr addr;
hwaddr len;
+ bool in_use;
} BounceBuffer;
static BounceBuffer bounce;
@@ -2570,7 +2571,7 @@ void *address_space_map(AddressSpace *as,
l = len;
mr = address_space_translate(as, addr, &xlat, &l, is_write);
if (!memory_access_is_direct(mr, is_write)) {
- if (bounce.buffer) {
+ if (atomic_xchg(&bounce.in_use, true)) {
return NULL;
}
/* Avoid unbounded allocations */
@@ -2640,6 +2641,7 @@ void address_space_unmap(AddressSpace *as, void *buffer,
hwaddr len,
qemu_vfree(bounce.buffer);
bounce.buffer = NULL;
memory_region_unref(bounce.mr);
+ atomic_mb_set(&bounce.in_use, false);
cpu_notify_map_clients();
}
--
2.3.5
- [Qemu-devel] [PULL 00/22] Memory, TCG, NBD, build system changes for 2015-04-27, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 01/22] translate-all: use glib for all page descriptor allocations, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 02/22] exec: Atomic access to bounce buffer,
Paolo Bonzini <=
- [Qemu-devel] [PULL 04/22] exec: Protect map_client_list with mutex, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 03/22] linux-user, bsd-user: Remove two calls to cpu_exec_init_all, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 05/22] exec: Notify cpu_register_map_client caller if the bounce buffer is available, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 06/22] dma-helpers: Fix race condition of continue_after_map_failure and dma_aio_cancel, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 07/22] memory: add memory_region_ram_resize, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 08/22] acpi-build: remove dependency from ram_addr.h, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 09/22] sun4m: fix slavio sysctrl and led register sizes, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 10/22] sb16: remove useless mixer_write_indexw, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 11/22] gus: clean up MemoryRegionPortio, Paolo Bonzini, 2015/04/28
- [Qemu-devel] [PULL 12/22] ide: there is only one data port, Paolo Bonzini, 2015/04/28