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[Qemu-devel] [PATCH 05/18] block: access wakeup with atomic ops
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 05/18] block: access wakeup with atomic ops |
Date: |
Thu, 11 May 2017 16:41:55 +0200 |
Signed-off-by: Paolo Bonzini <address@hidden>
---
v1->v2: add comment [Fam]
block/io.c | 3 ++-
block/nfs.c | 4 +++-
block/sheepdog.c | 3 ++-
include/block/block.h | 5 +++--
include/block/block_int.h | 7 +++++--
5 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/block/io.c b/block/io.c
index 28d2de6d93..dcb2b72f91 100644
--- a/block/io.c
+++ b/block/io.c
@@ -501,7 +501,8 @@ static void dummy_bh_cb(void *opaque)
void bdrv_wakeup(BlockDriverState *bs)
{
- if (bs->wakeup) {
+ /* The barrier (or an atomic op) is in the caller. */
+ if (atomic_read(&bs->wakeup)) {
aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
}
}
diff --git a/block/nfs.c b/block/nfs.c
index 6541dec1fc..ec75c6c4ca 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -736,7 +736,9 @@ nfs_get_allocated_file_size_cb(int ret, struct nfs_context
*nfs, void *data,
if (task->ret < 0) {
error_report("NFS Error: %s", nfs_get_error(nfs));
}
- task->complete = 1;
+
+ /* Set task->complete before reading bs->wakeup. */
+ atomic_mb_set(&task->complete, 1);
bdrv_wakeup(task->bs);
}
diff --git a/block/sheepdog.c b/block/sheepdog.c
index b2a5998188..dad998a2c7 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -704,7 +704,8 @@ out:
srco->co = NULL;
srco->ret = ret;
- srco->finished = true;
+ /* Set srco->finished before reading bs->wakeup. */
+ atomic_mb_set(&srco->finished, true);
if (srco->bs) {
bdrv_wakeup(srco->bs);
}
diff --git a/include/block/block.h b/include/block/block.h
index 144df0ddfb..bad445acd8 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -398,7 +398,8 @@ void bdrv_drain_all(void);
* block_job_defer_to_main_loop for how to do it). \
*/ \
assert(!bs_->wakeup); \
- bs_->wakeup = true; \
+ /* Set bs->wakeup before evaluating cond. */ \
+ atomic_mb_set(&bs_->wakeup, true); \
while (busy_) { \
if ((cond)) { \
waited_ = busy_ = true; \
@@ -410,7 +411,7 @@ void bdrv_drain_all(void);
waited_ |= busy_; \
} \
} \
- bs_->wakeup = false; \
+ atomic_set(&bs_->wakeup, false); \
} \
waited_; })
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 8db83c2b2d..0799098060 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -590,8 +590,6 @@ struct BlockDriverState {
/* Callback before write request is processed */
NotifierWithReturnList before_write_notifiers;
- bool wakeup;
-
/* Offset after the highest byte written to */
uint64_t wr_highest_offset;
@@ -622,6 +620,11 @@ struct BlockDriverState {
unsigned int in_flight;
unsigned int serialising_in_flight;
+ /* Internal to BDRV_POLL_WHILE and bdrv_wakeup. Accessed with atomic
+ * ops.
+ */
+ bool wakeup;
+
/* do we need to tell the quest if we have a volatile write cache? */
int enable_write_cache;
--
2.12.2
- [Qemu-devel] [PATCH v2 00/18] Block layer thread safety, part 1, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 01/18] block: access copy_on_read with atomic ops, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 04/18] block: access serialising_in_flight with atomic ops, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 03/18] block: access io_limits_disabled with atomic ops, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 02/18] block: access quiesce_counter with atomic ops, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 05/18] block: access wakeup with atomic ops,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 09/18] throttle-groups: protect throttled requests with a CoMutex, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 06/18] block: access io_plugged with atomic ops, Paolo Bonzini, 2017/05/11
- [Qemu-devel] [PATCH 08/18] throttle-groups: do not use qemu_co_enter_next, Paolo Bonzini, 2017/05/11