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[Qemu-devel] [PATCH 02/17] block-backend: allow blk_prw from coroutine c
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 02/17] block-backend: allow blk_prw from coroutine context |
Date: |
Fri, 20 Jan 2017 17:43:07 +0100 |
qcow2_create2 calls this. Do not run a nested event loop, as that
breaks when aio_co_wake tries to queue the coroutine on the co_queue_wakeup
list of the currently running one.
Reviewed-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
block/block-backend.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index efbf398..1177598 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -880,7 +880,6 @@ static int blk_prw(BlockBackend *blk, int64_t offset,
uint8_t *buf,
{
QEMUIOVector qiov;
struct iovec iov;
- Coroutine *co;
BlkRwCo rwco;
iov = (struct iovec) {
@@ -897,9 +896,14 @@ static int blk_prw(BlockBackend *blk, int64_t offset,
uint8_t *buf,
.ret = NOT_DONE,
};
- co = qemu_coroutine_create(co_entry, &rwco);
- qemu_coroutine_enter(co);
- BDRV_POLL_WHILE(blk_bs(blk), rwco.ret == NOT_DONE);
+ if (qemu_in_coroutine()) {
+ /* Fast-path if already in coroutine context */
+ co_entry(&rwco);
+ } else {
+ Coroutine *co = qemu_coroutine_create(co_entry, &rwco);
+ qemu_coroutine_enter(co);
+ BDRV_POLL_WHILE(blk_bs(blk), rwco.ret == NOT_DONE);
+ }
return rwco.ret;
}
--
2.9.3