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[Qemu-devel] [PATCH 15/16] async: remove unnecessary inc/dec pairs
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 15/16] async: remove unnecessary inc/dec pairs |
Date: |
Fri, 13 Jan 2017 14:17:30 +0100 |
Pull the increment/decrement pair out of aio_bh_poll and into the
callers.
Signed-off-by: Paolo Bonzini <address@hidden>
---
aio-posix.c | 8 +++-----
aio-win32.c | 8 ++++----
async.c | 12 ++++++------
3 files changed, 13 insertions(+), 15 deletions(-)
diff --git a/aio-posix.c b/aio-posix.c
index 51e92b8..2537bcd 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -425,9 +425,8 @@ static bool aio_dispatch_handlers(AioContext *ctx)
void aio_dispatch(AioContext *ctx)
{
- aio_bh_poll(ctx);
-
qemu_lockcnt_inc(&ctx->list_lock);
+ aio_bh_poll(ctx);
aio_dispatch_handlers(ctx);
qemu_lockcnt_dec(&ctx->list_lock);
@@ -678,16 +677,15 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
npfd = 0;
- qemu_lockcnt_dec(&ctx->list_lock);
progress |= aio_bh_poll(ctx);
if (ret > 0) {
- qemu_lockcnt_inc(&ctx->list_lock);
progress |= aio_dispatch_handlers(ctx);
- qemu_lockcnt_dec(&ctx->list_lock);
}
+ qemu_lockcnt_dec(&ctx->list_lock);
+
progress |= timerlistgroup_run_timers(&ctx->tlg);
return progress;
diff --git a/aio-win32.c b/aio-win32.c
index 442a179..bca496a 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -253,8 +253,6 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE
event)
bool progress = false;
AioHandler *tmp;
- qemu_lockcnt_inc(&ctx->list_lock);
-
/*
* We have to walk very carefully in case aio_set_fd_handler is
* called while we're walking.
@@ -305,14 +303,15 @@ static bool aio_dispatch_handlers(AioContext *ctx, HANDLE
event)
}
}
- qemu_lockcnt_dec(&ctx->list_lock);
return progress;
}
void aio_dispatch(AioContext *ctx)
{
+ qemu_lockcnt_inc(&ctx->list_lock);
aio_bh_poll(ctx);
aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE);
+ qemu_lockcnt_dec(&ctx->list_lock);
timerlistgroup_run_timers(&ctx->tlg);
}
@@ -349,7 +348,6 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
}
- qemu_lockcnt_dec(&ctx->list_lock);
first = true;
/* ctx->notifier is always registered. */
@@ -392,6 +390,8 @@ bool aio_poll(AioContext *ctx, bool blocking)
progress |= aio_dispatch_handlers(ctx, event);
} while (count > 0);
+ qemu_lockcnt_dec(&ctx->list_lock);
+
progress |= timerlistgroup_run_timers(&ctx->tlg);
return progress;
}
diff --git a/async.c b/async.c
index 1839aa5..c471b1e 100644
--- a/async.c
+++ b/async.c
@@ -89,15 +89,16 @@ void aio_bh_call(QEMUBH *bh)
bh->cb(bh->opaque);
}
-/* Multiple occurrences of aio_bh_poll cannot be called concurrently */
+/* Multiple occurrences of aio_bh_poll cannot be called concurrently.
+ * The count in ctx->list_lock is incremented before the call, and is
+ * not affected by the call.
+ */
int aio_bh_poll(AioContext *ctx)
{
QEMUBH *bh, **bhp, *next;
int ret;
bool deleted = false;
- qemu_lockcnt_inc(&ctx->list_lock);
-
ret = 0;
for (bh = atomic_rcu_read(&ctx->first_bh); bh; bh = next) {
next = atomic_rcu_read(&bh->next);
@@ -122,11 +123,10 @@ int aio_bh_poll(AioContext *ctx)
/* remove deleted bhs */
if (!deleted) {
- qemu_lockcnt_dec(&ctx->list_lock);
return ret;
}
- if (qemu_lockcnt_dec_and_lock(&ctx->list_lock)) {
+ if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) {
bhp = &ctx->first_bh;
while (*bhp) {
bh = *bhp;
@@ -137,7 +137,7 @@ int aio_bh_poll(AioContext *ctx)
bhp = &bh->next;
}
}
- qemu_lockcnt_unlock(&ctx->list_lock);
+ qemu_lockcnt_inc_and_unlock(&ctx->list_lock);
}
return ret;
}
--
2.9.3
- Re: [Qemu-devel] [PATCH 01/16] aio: introduce aio_co_schedule and aio_co_wake, (continued)
- [Qemu-devel] [PATCH 06/16] nbd: do not block on partial reply header reads, Paolo Bonzini, 2017/01/13
- [Qemu-devel] [PATCH 08/16] qed: introduce qed_aio_start_io and qed_aio_next_io_cb, Paolo Bonzini, 2017/01/13
- [Qemu-devel] [PATCH 09/16] aio: push aio_context_acquire/release down to dispatching, Paolo Bonzini, 2017/01/13
- [Qemu-devel] [PATCH 15/16] async: remove unnecessary inc/dec pairs,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 13/16] block: explicitly acquire aiocontext in aio callbacks that need it, Paolo Bonzini, 2017/01/13
- [Qemu-devel] [PATCH 16/16] block: document fields protected by AioContext lock, Paolo Bonzini, 2017/01/13
- [Qemu-devel] [PATCH 10/16] block: explicitly acquire aiocontext in timers that need it, Paolo Bonzini, 2017/01/13
- Re: [Qemu-devel] [PATCH 10/16] block: explicitly acquire aiocontext in timers that need it, Stefan Hajnoczi, 2017/01/18