diff mbox

[RFC,07/13] block: add thread_aio_context TLS variable

Message ID 1371203313-26490-8-git-send-email-stefanha@redhat.com
State New
Headers show

Commit Message

Stefan Hajnoczi June 14, 2013, 9:48 a.m. UTC 
BH and fd handler APIs need to know which AioContext (event loop) to run
inside.  Passing it around everywhere is not feasible since it would
require adding arguments to any call-chain that invokes BH and fd
handler APIs (hint: there are many and they change).

Instead make the AioContext pointer thread-local.  This way, any
function that needs to use an AioContext can find it.  In particular:
the iothread and vcpu threads share the main AioContext since they hold
the global mutex while running.  Dataplane threads will use their own
AioContexts.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 async.c             | 2 ++
 cpus.c              | 2 ++
 include/block/aio.h | 4 ++++
 main-loop.c         | 1 +
 4 files changed, 9 insertions(+)
diff mbox

Patch

diff --git a/async.c b/async.c
index 90fe906..765cbc0 100644
--- a/async.c
+++ b/async.c
@@ -27,6 +27,8 @@ 
 #include "block/thread-pool.h"
 #include "qemu/main-loop.h"
 
+DEFINE_TLS(AioContext*, thread_aio_context);
+
 /***********************************************************/
 /* bottom halves (can be seen as timers which expire ASAP) */
 
diff --git a/cpus.c b/cpus.c
index c232265..529d612 100644
--- a/cpus.c
+++ b/cpus.c
@@ -741,6 +741,7 @@  static void *qemu_kvm_cpu_thread_fn(void *arg)
     qemu_thread_get_self(cpu->thread);
     cpu->thread_id = qemu_get_thread_id();
     cpu_single_env = env;
+    *alloc_thread_aio_context() = qemu_get_aio_context();
 
     r = kvm_init_vcpu(cpu);
     if (r < 0) {
@@ -815,6 +816,7 @@  static void tcg_exec_all(void);
 static void tcg_signal_cpu_creation(CPUState *cpu, void *data)
 {
     cpu->thread_id = qemu_get_thread_id();
+    *alloc_thread_aio_context() = qemu_get_aio_context();
     cpu->created = true;
 }
 
diff --git a/include/block/aio.h b/include/block/aio.h
index 1836793..6ee9369 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -17,6 +17,7 @@ 
 #include "qemu-common.h"
 #include "qemu/queue.h"
 #include "qemu/event_notifier.h"
+#include "qemu/tls.h"
 
 typedef struct BlockDriverAIOCB BlockDriverAIOCB;
 typedef void BlockDriverCompletionFunc(void *opaque, int ret);
@@ -74,6 +75,9 @@  typedef struct AioContext {
 /* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
 typedef int (AioFlushEventNotifierHandler)(EventNotifier *e);
 
+/* Each thread can have a default AioContext */
+DECLARE_TLS(AioContext*, thread_aio_context);
+
 /**
  * aio_context_new: Allocate a new AioContext.
  *
diff --git a/main-loop.c b/main-loop.c
index cf36645..51eeb0f 100644
--- a/main-loop.c
+++ b/main-loop.c
@@ -142,6 +142,7 @@  int qemu_init_main_loop(void)
 
     gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
     qemu_aio_context = aio_context_new();
+    *get_thread_aio_context() = qemu_aio_context;
     src = aio_get_g_source(qemu_aio_context);
     g_source_attach(src, NULL);
     g_source_unref(src);