Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
aio-posix.c | 54 ++++++++++++++++++++++++++++++++----------------------
1 file changed, 32 insertions(+), 22 deletions(-)
diff --git a/aio-posix.c b/aio-posix.c
index 450da51..cbdc6e4 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -16,7 +16,7 @@
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "block/block.h"
-#include "qemu/queue.h"
+#include "qemu/rcu_queue.h"
#include "qemu/sockets.h"
#ifdef CONFIG_EPOLL
#include <sys/epoll.h>
@@ -213,6 +213,8 @@ void aio_set_fd_handler(AioContext *ctx,
bool is_new = false;
bool deleted = false;
+ qemu_lockcnt_lock(&ctx->list_lock);
+
node = find_aio_handler(ctx, fd);
/* Are we deleting the fd handler? */
@@ -220,14 +222,14 @@ void aio_set_fd_handler(AioContext *ctx,
if (node) {
g_source_remove_poll(&ctx->source, &node->pfd);
- /* If the lock is held, just mark the node as deleted */
- if (ctx->walking_handlers) {
+ /* If aio_poll is in progress, just mark the node as deleted */
+ if (qemu_lockcnt_count(&ctx->list_lock)) {
node->deleted = 1;
node->pfd.revents = 0;
} else {
/* Otherwise, delete it for real. We can't just mark it as
* deleted because deleted nodes are only cleaned up after
- * releasing the walking_handlers lock.
+ * releasing the list_lock.
*/
QLIST_REMOVE(node, node);
deleted = true;
@@ -238,7 +240,7 @@ void aio_set_fd_handler(AioContext *ctx,
/* Alloc and insert if it's not already there */
node = g_new0(AioHandler, 1);
node->pfd.fd = fd;
- QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
+ QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node);
g_source_add_poll(&ctx->source, &node->pfd);
is_new = true;
@@ -254,6 +256,7 @@ void aio_set_fd_handler(AioContext *ctx,
}
aio_epoll_update(ctx, node, is_new);
+ qemu_lockcnt_unlock(&ctx->list_lock);
aio_notify(ctx);
if (deleted) {
g_free(node);
@@ -277,20 +280,30 @@ bool aio_prepare(AioContext *ctx)
bool aio_pending(AioContext *ctx)
{
AioHandler *node;
+ bool result = false;
- QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ /*
+ * We have to walk very carefully in case aio_set_fd_handler is
+ * called while we're walking.
+ */
+ qemu_lockcnt_inc(&ctx->list_lock);
+
+ QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
int revents;
revents = node->pfd.revents & node->pfd.events;
if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
- return true;
+ result = true;
+ break;
}
if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
- return true;
+ result = true;
+ break;
}
}
+ qemu_lockcnt_dec(&ctx->list_lock);
- return false;
+ return result;
}
bool aio_dispatch(AioContext *ctx)
@@ -311,13 +324,12 @@ bool aio_dispatch(AioContext *ctx)
* We have to walk very carefully in case aio_set_fd_handler is
* called while we're walking.
*/
- ctx->walking_handlers++;
+ qemu_lockcnt_inc(&ctx->list_lock);
- QLIST_FOREACH_SAFE(node, &ctx->aio_handlers, node, tmp) {
+ QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) {
int revents;
- revents = node->pfd.revents & node->pfd.events;
- node->pfd.revents = 0;
+ revents = atomic_xchg(&node->pfd.revents, 0) & node->pfd.events;
if (!node->deleted &&
(revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
@@ -337,16 +349,15 @@ bool aio_dispatch(AioContext *ctx)
}
if (node->deleted) {
- ctx->walking_handlers--;
- if (!ctx->walking_handlers) {
+ if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
QLIST_REMOVE(node, node);
g_free(node);
+ qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
}
- ctx->walking_handlers++;
}
}
- ctx->walking_handlers--;
+ qemu_lockcnt_dec(&ctx->list_lock);
/* Run our timers */
progress |= timerlistgroup_run_timers(&ctx->tlg);
@@ -421,12 +432,11 @@ bool aio_poll_internal(AioContext *ctx, bool blocking)
atomic_add(&ctx->notify_me, 2);
}
- ctx->walking_handlers++;
-
+ qemu_lockcnt_inc(&ctx->list_lock);
assert(npfd == 0);
/* fill pollfds */
- QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+ QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
if (!node->deleted && node->pfd.events
&& !aio_epoll_enabled(ctx)
&& aio_node_check(ctx, node->is_external)) {
@@ -463,12 +473,12 @@ bool aio_poll_internal(AioContext *ctx, bool blocking)
/* if we have any readable fds, dispatch event */
if (ret > 0) {
for (i = 0; i < npfd; i++) {
- nodes[i]->pfd.revents = pollfds[i].revents;
+ atomic_or(&nodes[i]->pfd.revents, pollfds[i].revents);
}
}
npfd = 0;
- ctx->walking_handlers--;
+ qemu_lockcnt_dec(&ctx->list_lock);
/* Run dispatch even if there were no readable fds to run timers */
if (aio_dispatch(ctx)) {
--
2.5.0
