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authorPeter Maydell <peter.maydell@linaro.org>2017-04-18 16:18:15 +0100
committerPeter Maydell <peter.maydell@linaro.org>2017-04-18 16:18:15 +0100
commitd1263f8f1805ffe6a9da8520a6aa96062bc794f4 (patch)
treec5fa1810e634b8bd725bd2eaafccffb4362c1552
parent9c6b899f7a46893ab3b671e341a2234e9c0c060e (diff)
parent91af091f92358c2ff828fa1def1a7bea9b701cdf (diff)
downloadqemu-arm-d1263f8f1805ffe6a9da8520a6aa96062bc794f4.tar.gz
Merge remote-tracking branch 'remotes/famz/tags/block-pull-request' into staging
# gpg: Signature made Tue 18 Apr 2017 15:58:32 BST # gpg: using RSA key 0xCA35624C6A9171C6 # gpg: Good signature from "Fam Zheng <famz@redhat.com>" # gpg: WARNING: This key is not certified with sufficiently trusted signatures! # gpg: It is not certain that the signature belongs to the owner. # Primary key fingerprint: 5003 7CB7 9706 0F76 F021 AD56 CA35 624C 6A91 71C6 * remotes/famz/tags/block-pull-request: block: Drain BH in bdrv_drained_begin block: Walk bs->children carefully in bdrv_drain_recurse Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
-rw-r--r--block/io.c23
-rw-r--r--include/block/block.h22
2 files changed, 34 insertions, 11 deletions
diff --git a/block/io.c b/block/io.c
index 8706bfa578..a7142e00e8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -158,7 +158,7 @@ bool bdrv_requests_pending(BlockDriverState *bs)
static bool bdrv_drain_recurse(BlockDriverState *bs)
{
- BdrvChild *child;
+ BdrvChild *child, *tmp;
bool waited;
waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0);
@@ -167,8 +167,25 @@ static bool bdrv_drain_recurse(BlockDriverState *bs)
bs->drv->bdrv_drain(bs);
}
- QLIST_FOREACH(child, &bs->children, next) {
- waited |= bdrv_drain_recurse(child->bs);
+ QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
+ BlockDriverState *bs = child->bs;
+ bool in_main_loop =
+ qemu_get_current_aio_context() == qemu_get_aio_context();
+ assert(bs->refcnt > 0);
+ if (in_main_loop) {
+ /* In case the recursive bdrv_drain_recurse processes a
+ * block_job_defer_to_main_loop BH and modifies the graph,
+ * let's hold a reference to bs until we are done.
+ *
+ * IOThread doesn't have such a BH, and it is not safe to call
+ * bdrv_unref without BQL, so skip doing it there.
+ */
+ bdrv_ref(bs);
+ }
+ waited |= bdrv_drain_recurse(bs);
+ if (in_main_loop) {
+ bdrv_unref(bs);
+ }
}
return waited;
diff --git a/include/block/block.h b/include/block/block.h
index 97d4330292..5ddc0cf21b 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -381,12 +381,13 @@ void bdrv_drain_all(void);
#define BDRV_POLL_WHILE(bs, cond) ({ \
bool waited_ = false; \
+ bool busy_ = true; \
BlockDriverState *bs_ = (bs); \
AioContext *ctx_ = bdrv_get_aio_context(bs_); \
if (aio_context_in_iothread(ctx_)) { \
- while ((cond)) { \
- aio_poll(ctx_, true); \
- waited_ = true; \
+ while ((cond) || busy_) { \
+ busy_ = aio_poll(ctx_, (cond)); \
+ waited_ |= !!(cond) | busy_; \
} \
} else { \
assert(qemu_get_current_aio_context() == \
@@ -398,11 +399,16 @@ void bdrv_drain_all(void);
*/ \
assert(!bs_->wakeup); \
bs_->wakeup = true; \
- while ((cond)) { \
- aio_context_release(ctx_); \
- aio_poll(qemu_get_aio_context(), true); \
- aio_context_acquire(ctx_); \
- waited_ = true; \
+ while (busy_) { \
+ if ((cond)) { \
+ waited_ = busy_ = true; \
+ aio_context_release(ctx_); \
+ aio_poll(qemu_get_aio_context(), true); \
+ aio_context_acquire(ctx_); \
+ } else { \
+ busy_ = aio_poll(ctx_, false); \
+ waited_ |= busy_; \
+ } \
} \
bs_->wakeup = false; \
} \