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Merge remote-tracking branch 'remotes/famz/tags/block-and-testing-pull-request' into staging

# gpg: Signature made Mon 17 Jul 2017 04:47:05 BST
# gpg:                using RSA key 0xCA35624C6A9171C6
# gpg: Good signature from "Fam Zheng <famz@redhat.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 5003 7CB7 9706 0F76 F021  AD56 CA35 624C 6A91 71C6

* remotes/famz/tags/block-and-testing-pull-request:
  travis: add no-TCG build
  docker.py: Improve subprocess exit code handling
  docker.py: Drop infile parameter
  docker: Don't enable networking as a side-effect of DEBUG=1
  ssh: support I/O from any AioContext
  sheepdog: add queue_lock
  qed: protect table cache with CoMutex
  qed: introduce bdrv_qed_init_state
  block: invoke .bdrv_drain callback in coroutine context and from AioContext
  qed: move tail of qed_aio_write_main to qed_aio_write_{cow, alloc}
  vvfat: make it thread-safe
  vpc: make it thread-safe
  vdi: make it thread-safe
  coroutine-lock: add qemu_co_rwlock_downgrade and qemu_co_rwlock_upgrade
  qcow2: call CoQueue APIs under CoMutex

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2017-07-17 11:46:36 +01:00
commit 6632f6ff96
18 changed files with 355 additions and 161 deletions
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3
.travis.yml
View File

@ -86,6 +86,9 @@ matrix:
- env: CONFIG="--enable-trace-backends=ust"
TEST_CMD=""
compiler: gcc
- env: CONFIG="--disable-tcg"
TEST_CMD=""
compiler: gcc
- env: CONFIG=""
os: osx
compiler: clang

42
block/io.c
View File

@ -149,6 +149,37 @@ bool bdrv_requests_pending(BlockDriverState *bs)
return false;
}
typedef struct {
Coroutine *co;
BlockDriverState *bs;
bool done;
} BdrvCoDrainData;
static void coroutine_fn bdrv_drain_invoke_entry(void *opaque)
{
BdrvCoDrainData *data = opaque;
BlockDriverState *bs = data->bs;
bs->drv->bdrv_co_drain(bs);
/* Set data->done before reading bs->wakeup. */
atomic_mb_set(&data->done, true);
bdrv_wakeup(bs);
}
static void bdrv_drain_invoke(BlockDriverState *bs)
{
BdrvCoDrainData data = { .bs = bs, .done = false };
if (!bs->drv || !bs->drv->bdrv_co_drain) {
return;
}
data.co = qemu_coroutine_create(bdrv_drain_invoke_entry, &data);
bdrv_coroutine_enter(bs, data.co);
BDRV_POLL_WHILE(bs, !data.done);
}
static bool bdrv_drain_recurse(BlockDriverState *bs)
{
BdrvChild *child, *tmp;
@ -156,9 +187,8 @@ static bool bdrv_drain_recurse(BlockDriverState *bs)
waited = BDRV_POLL_WHILE(bs, atomic_read(&bs->in_flight) > 0);
if (bs->drv && bs->drv->bdrv_drain) {
bs->drv->bdrv_drain(bs);
}
/* Ensure any pending metadata writes are submitted to bs->file. */
bdrv_drain_invoke(bs);
QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) {
BlockDriverState *bs = child->bs;
@ -184,12 +214,6 @@ static bool bdrv_drain_recurse(BlockDriverState *bs)
return waited;
}
typedef struct {
Coroutine *co;
BlockDriverState *bs;
bool done;
} BdrvCoDrainData;
static void bdrv_co_drain_bh_cb(void *opaque)
{
BdrvCoDrainData *data = opaque;

4
block/qcow2.c
View File

@ -2025,8 +2025,6 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState *bs, uint64_t offset,
ret = 0;
fail:
qemu_co_mutex_unlock(&s->lock);
while (l2meta != NULL) {
QCowL2Meta *next;
@ -2040,6 +2038,8 @@ fail:
l2meta = next;
}
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cluster_data);
trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);

4
block/qed-cluster.c
View File

@ -85,6 +85,8 @@ static unsigned int qed_count_contiguous_clusters(BDRVQEDState *s,
*
* On failure QED_CLUSTER_L2 or QED_CLUSTER_L1 is returned for missing L2 or L1
* table offset, respectively. len is number of contiguous unallocated bytes.
*
* Called with table_lock held.
*/
int coroutine_fn qed_find_cluster(BDRVQEDState *s, QEDRequest *request,
uint64_t pos, size_t *len,
@ -112,7 +114,6 @@ int coroutine_fn qed_find_cluster(BDRVQEDState *s, QEDRequest *request,
}
ret = qed_read_l2_table(s, request, l2_offset);
qed_acquire(s);
if (ret) {
goto out;
}
@ -137,6 +138,5 @@ int coroutine_fn qed_find_cluster(BDRVQEDState *s, QEDRequest *request,
out:
*img_offset = offset;
qed_release(s);
return ret;
}

6
block/qed-l2-cache.c
View File

@ -101,6 +101,8 @@ CachedL2Table *qed_alloc_l2_cache_entry(L2TableCache *l2_cache)
/**
* Decrease an entry's reference count and free if necessary when the reference
* count drops to zero.
*
* Called with table_lock held.
*/
void qed_unref_l2_cache_entry(CachedL2Table *entry)
{
@ -122,6 +124,8 @@ void qed_unref_l2_cache_entry(CachedL2Table *entry)
*
* For a cached entry, this function increases the reference count and returns
* the entry.
*
* Called with table_lock held.
*/
CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset)
{
@ -150,6 +154,8 @@ CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset)
* N.B. This function steals a reference to the l2_table from the caller so the
* caller must obtain a new reference by issuing a call to
* qed_find_l2_cache_entry().
*
* Called with table_lock held.
*/
void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table)
{

24
block/qed-table.c
View File

@ -18,6 +18,7 @@
#include "qed.h"
#include "qemu/bswap.h"
/* Called either from qed_check or with table_lock held. */
static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
{
QEMUIOVector qiov;
@ -32,18 +33,22 @@ static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
trace_qed_read_table(s, offset, table);
if (qemu_in_coroutine()) {
qemu_co_mutex_unlock(&s->table_lock);
}
ret = bdrv_preadv(s->bs->file, offset, &qiov);
if (qemu_in_coroutine()) {
qemu_co_mutex_lock(&s->table_lock);
}
if (ret < 0) {
goto out;
}
/* Byteswap offsets */
qed_acquire(s);
noffsets = qiov.size / sizeof(uint64_t);
for (i = 0; i < noffsets; i++) {
table->offsets[i] = le64_to_cpu(table->offsets[i]);
}
qed_release(s);
ret = 0;
out:
@ -61,6 +66,8 @@ out:
* @index: Index of first element
* @n: Number of elements
* @flush: Whether or not to sync to disk
*
* Called either from qed_check or with table_lock held.
*/
static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
unsigned int index, unsigned int n, bool flush)
@ -97,16 +104,20 @@ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
/* Adjust for offset into table */
offset += start * sizeof(uint64_t);
if (qemu_in_coroutine()) {
qemu_co_mutex_unlock(&s->table_lock);
}
ret = bdrv_pwritev(s->bs->file, offset, &qiov);
if (qemu_in_coroutine()) {
qemu_co_mutex_lock(&s->table_lock);
}
trace_qed_write_table_cb(s, table, flush, ret);
if (ret < 0) {
goto out;
}
if (flush) {
qed_acquire(s);
ret = bdrv_flush(s->bs);
qed_release(s);
if (ret < 0) {
goto out;
}
@ -123,6 +134,7 @@ int qed_read_l1_table_sync(BDRVQEDState *s)
return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
}
/* Called either from qed_check or with table_lock held. */
int qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n)
{
BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
@ -136,6 +148,7 @@ int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
return qed_write_l1_table(s, index, n);
}
/* Called either from qed_check or with table_lock held. */
int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
{
int ret;
@ -154,7 +167,6 @@ int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD);
ret = qed_read_table(s, offset, request->l2_table->table);
qed_acquire(s);
if (ret) {
/* can't trust loaded L2 table anymore */
qed_unref_l2_cache_entry(request->l2_table);
@ -170,7 +182,6 @@ int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
assert(request->l2_table != NULL);
}
qed_release(s);
return ret;
}
@ -180,6 +191,7 @@ int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, uint64_t offset
return qed_read_l2_table(s, request, offset);
}
/* Called either from qed_check or with table_lock held. */
int qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
unsigned int index, unsigned int n, bool flush)
{

218
block/qed.c
View File

@ -93,6 +93,8 @@ int qed_write_header_sync(BDRVQEDState *s)
*
* This function only updates known header fields in-place and does not affect
* extra data after the QED header.
*
* No new allocating reqs can start while this function runs.
*/
static int coroutine_fn qed_write_header(BDRVQEDState *s)
{
@ -109,6 +111,8 @@ static int coroutine_fn qed_write_header(BDRVQEDState *s)
QEMUIOVector qiov;
int ret;
assert(s->allocating_acb || s->allocating_write_reqs_plugged);
buf = qemu_blockalign(s->bs, len);
iov = (struct iovec) {
.iov_base = buf,
@ -219,6 +223,8 @@ static int qed_read_string(BdrvChild *file, uint64_t offset, size_t n,
* This function only produces the offset where the new clusters should be
* written. It updates BDRVQEDState but does not make any changes to the image
* file.
*
* Called with table_lock held.
*/
static uint64_t qed_alloc_clusters(BDRVQEDState *s, unsigned int n)
{
@ -236,6 +242,8 @@ QEDTable *qed_alloc_table(BDRVQEDState *s)
/**
* Allocate a new zeroed L2 table
*
* Called with table_lock held.
*/
static CachedL2Table *qed_new_l2_table(BDRVQEDState *s)
{
@ -249,19 +257,32 @@ static CachedL2Table *qed_new_l2_table(BDRVQEDState *s)
return l2_table;
}
static void qed_plug_allocating_write_reqs(BDRVQEDState *s)
static bool qed_plug_allocating_write_reqs(BDRVQEDState *s)
{
qemu_co_mutex_lock(&s->table_lock);
/* No reentrancy is allowed. */
assert(!s->allocating_write_reqs_plugged);
if (s->allocating_acb != NULL) {
/* Another allocating write came concurrently. This cannot happen
* from bdrv_qed_co_drain, but it can happen when the timer runs.
*/
qemu_co_mutex_unlock(&s->table_lock);
return false;
}
s->allocating_write_reqs_plugged = true;
qemu_co_mutex_unlock(&s->table_lock);
return true;
}
static void qed_unplug_allocating_write_reqs(BDRVQEDState *s)
{
qemu_co_mutex_lock(&s->table_lock);
assert(s->allocating_write_reqs_plugged);
s->allocating_write_reqs_plugged = false;
qemu_co_enter_next(&s->allocating_write_reqs);
qemu_co_queue_next(&s->allocating_write_reqs);
qemu_co_mutex_unlock(&s->table_lock);
}
static void coroutine_fn qed_need_check_timer_entry(void *opaque)
@ -269,17 +290,14 @@ static void coroutine_fn qed_need_check_timer_entry(void *opaque)
BDRVQEDState *s = opaque;
int ret;
/* The timer should only fire when allocating writes have drained */
assert(!s->allocating_acb);
trace_qed_need_check_timer_cb(s);
qed_acquire(s);
qed_plug_allocating_write_reqs(s);
if (!qed_plug_allocating_write_reqs(s)) {
return;
}
/* Ensure writes are on disk before clearing flag */
ret = bdrv_co_flush(s->bs->file->bs);
qed_release(s);
if (ret < 0) {
qed_unplug_allocating_write_reqs(s);
return;
@ -301,16 +319,6 @@ static void qed_need_check_timer_cb(void *opaque)
qemu_coroutine_enter(co);
}
void qed_acquire(BDRVQEDState *s)
{
aio_context_acquire(bdrv_get_aio_context(s->bs));
}
void qed_release(BDRVQEDState *s)
{
aio_context_release(bdrv_get_aio_context(s->bs));
}
static void qed_start_need_check_timer(BDRVQEDState *s)
{
trace_qed_start_need_check_timer(s);
@ -350,7 +358,7 @@ static void bdrv_qed_attach_aio_context(BlockDriverState *bs,
}
}
static void bdrv_qed_drain(BlockDriverState *bs)
static void coroutine_fn bdrv_qed_co_drain(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
@ -359,10 +367,20 @@ static void bdrv_qed_drain(BlockDriverState *bs)
*/
if (s->need_check_timer && timer_pending(s->need_check_timer)) {
qed_cancel_need_check_timer(s);
qed_need_check_timer_cb(s);
qed_need_check_timer_entry(s);
}
}
static void bdrv_qed_init_state(BlockDriverState *bs)
{
BDRVQEDState *s = bs->opaque;
memset(s, 0, sizeof(BDRVQEDState));
s->bs = bs;
qemu_co_mutex_init(&s->table_lock);
qemu_co_queue_init(&s->allocating_write_reqs);
}
static int bdrv_qed_do_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
@ -371,9 +389,6 @@ static int bdrv_qed_do_open(BlockDriverState *bs, QDict *options, int flags,
int64_t file_size;
int ret;
s->bs = bs;
qemu_co_queue_init(&s->allocating_write_reqs);
ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header));
if (ret < 0) {
return ret;
@ -507,6 +522,7 @@ static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
return -EINVAL;
}
bdrv_qed_init_state(bs);
return bdrv_qed_do_open(bs, options, flags, errp);
}
@ -681,6 +697,7 @@ typedef struct {
BlockDriverState **file;
} QEDIsAllocatedCB;
/* Called with table_lock held. */
static void qed_is_allocated_cb(void *opaque, int ret, uint64_t offset, size_t len)
{
QEDIsAllocatedCB *cb = opaque;
@ -728,6 +745,7 @@ static int64_t coroutine_fn bdrv_qed_co_get_block_status(BlockDriverState *bs,
uint64_t offset;
int ret;
qemu_co_mutex_lock(&s->table_lock);
ret = qed_find_cluster(s, &request, cb.pos, &len, &offset);
qed_is_allocated_cb(&cb, ret, offset, len);
@ -735,6 +753,7 @@ static int64_t coroutine_fn bdrv_qed_co_get_block_status(BlockDriverState *bs,
assert(cb.status != BDRV_BLOCK_OFFSET_MASK);
qed_unref_l2_cache_entry(request.l2_table);
qemu_co_mutex_unlock(&s->table_lock);
return cb.status;
}
@ -865,6 +884,8 @@ out:
*
* The cluster offset may be an allocated byte offset in the image file, the
* zero cluster marker, or the unallocated cluster marker.
*
* Called with table_lock held.
*/
static void coroutine_fn qed_update_l2_table(BDRVQEDState *s, QEDTable *table,
int index, unsigned int n,
@ -880,6 +901,7 @@ static void coroutine_fn qed_update_l2_table(BDRVQEDState *s, QEDTable *table,
}
}
/* Called with table_lock held. */
static void coroutine_fn qed_aio_complete(QEDAIOCB *acb)
{
BDRVQEDState *s = acb_to_s(acb);
@ -903,7 +925,7 @@ static void coroutine_fn qed_aio_complete(QEDAIOCB *acb)
if (acb == s->allocating_acb) {
s->allocating_acb = NULL;
if (!qemu_co_queue_empty(&s->allocating_write_reqs)) {
qemu_co_enter_next(&s->allocating_write_reqs);
qemu_co_queue_next(&s->allocating_write_reqs);
} else if (s->header.features & QED_F_NEED_CHECK) {
qed_start_need_check_timer(s);
}
@ -912,6 +934,8 @@ static void coroutine_fn qed_aio_complete(QEDAIOCB *acb)
/**
* Update L1 table with new L2 table offset and write it out
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_l1_update(QEDAIOCB *acb)
{
@ -940,6 +964,8 @@ static int coroutine_fn qed_aio_write_l1_update(QEDAIOCB *acb)
/**
* Update L2 table with new cluster offsets and write them out
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_l2_update(QEDAIOCB *acb, uint64_t offset)
{
@ -976,50 +1002,26 @@ static int coroutine_fn qed_aio_write_l2_update(QEDAIOCB *acb, uint64_t offset)
/**
* Write data to the image file
*
* Called with table_lock *not* held.
*/
static int coroutine_fn qed_aio_write_main(QEDAIOCB *acb)
{
BDRVQEDState *s = acb_to_s(acb);
uint64_t offset = acb->cur_cluster +
qed_offset_into_cluster(s, acb->cur_pos);
int ret;
trace_qed_aio_write_main(s, acb, 0, offset, acb->cur_qiov.size);
BLKDBG_EVENT(s->bs->file, BLKDBG_WRITE_AIO);
ret = bdrv_co_pwritev(s->bs->file, offset, acb->cur_qiov.size,
&acb->cur_qiov, 0);
if (ret < 0) {
return ret;
}
if (acb->find_cluster_ret != QED_CLUSTER_FOUND) {
if (s->bs->backing) {
/*
* Flush new data clusters before updating the L2 table
*
* This flush is necessary when a backing file is in use. A crash
* during an allocating write could result in empty clusters in the
* image. If the write only touched a subregion of the cluster,
* then backing image sectors have been lost in the untouched
* region. The solution is to flush after writing a new data
* cluster and before updating the L2 table.
*/
ret = bdrv_co_flush(s->bs->file->bs);
if (ret < 0) {
return ret;
}
}
ret = qed_aio_write_l2_update(acb, acb->cur_cluster);
if (ret < 0) {
return ret;
}
}
return 0;
return bdrv_co_pwritev(s->bs->file, offset, acb->cur_qiov.size,
&acb->cur_qiov, 0);
}
/**
* Populate untouched regions of new data cluster
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_cow(QEDAIOCB *acb)
{
@ -1027,6 +1029,8 @@ static int coroutine_fn qed_aio_write_cow(QEDAIOCB *acb)
uint64_t start, len, offset;
int ret;
qemu_co_mutex_unlock(&s->table_lock);
/* Populate front untouched region of new data cluster */
start = qed_start_of_cluster(s, acb->cur_pos);
len = qed_offset_into_cluster(s, acb->cur_pos);
@ -1034,7 +1038,7 @@ static int coroutine_fn qed_aio_write_cow(QEDAIOCB *acb)
trace_qed_aio_write_prefill(s, acb, start, len, acb->cur_cluster);
ret = qed_copy_from_backing_file(s, start, len, acb->cur_cluster);
if (ret < 0) {
return ret;
goto out;
}
/* Populate back untouched region of new data cluster */
@ -1047,10 +1051,31 @@ static int coroutine_fn qed_aio_write_cow(QEDAIOCB *acb)
trace_qed_aio_write_postfill(s, acb, start, len, offset);
ret = qed_copy_from_backing_file(s, start, len, offset);
if (ret < 0) {
return ret;
goto out;
}
return qed_aio_write_main(acb);
ret = qed_aio_write_main(acb);
if (ret < 0) {
goto out;
}
if (s->bs->backing) {
/*
* Flush new data clusters before updating the L2 table
*
* This flush is necessary when a backing file is in use. A crash
* during an allocating write could result in empty clusters in the
* image. If the write only touched a subregion of the cluster,
* then backing image sectors have been lost in the untouched
* region. The solution is to flush after writing a new data
* cluster and before updating the L2 table.
*/
ret = bdrv_co_flush(s->bs->file->bs);
}
out:
qemu_co_mutex_lock(&s->table_lock);
return ret;
}
/**
@ -1073,6 +1098,8 @@ static bool qed_should_set_need_check(BDRVQEDState *s)
* @len: Length in bytes
*
* This path is taken when writing to previously unallocated clusters.
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
{
@ -1087,7 +1114,7 @@ static int coroutine_fn qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
/* Freeze this request if another allocating write is in progress */
if (s->allocating_acb != acb || s->allocating_write_reqs_plugged) {
if (s->allocating_acb != NULL) {
qemu_co_queue_wait(&s->allocating_write_reqs, NULL);
qemu_co_queue_wait(&s->allocating_write_reqs, &s->table_lock);
assert(s->allocating_acb == NULL);
}
s->allocating_acb = acb;
@ -1103,6 +1130,7 @@ static int coroutine_fn qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
if (acb->find_cluster_ret == QED_CLUSTER_ZERO) {
return 0;
}
acb->cur_cluster = 1;
} else {
acb->cur_cluster = qed_alloc_clusters(s, acb->cur_nclusters);
}
@ -1115,15 +1143,14 @@ static int coroutine_fn qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
}
}
if (acb->flags & QED_AIOCB_ZERO) {
ret = qed_aio_write_l2_update(acb, 1);
} else {
if (!(acb->flags & QED_AIOCB_ZERO)) {
ret = qed_aio_write_cow(acb);
if (ret < 0) {
return ret;
}
}
if (ret < 0) {
return ret;
}
return 0;
return qed_aio_write_l2_update(acb, acb->cur_cluster);
}
/**
@ -1134,10 +1161,17 @@ static int coroutine_fn qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
* @len: Length in bytes
*
* This path is taken when writing to already allocated clusters.
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset,
size_t len)
{
BDRVQEDState *s = acb_to_s(acb);
int r;
qemu_co_mutex_unlock(&s->table_lock);
/* Allocate buffer for zero writes */
if (acb->flags & QED_AIOCB_ZERO) {
struct iovec *iov = acb->qiov->iov;
@ -1145,7 +1179,8 @@ static int coroutine_fn qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset,
if (!iov->iov_base) {
iov->iov_base = qemu_try_blockalign(acb->bs, iov->iov_len);
if (iov->iov_base == NULL) {
return -ENOMEM;
r = -ENOMEM;
goto out;
}
memset(iov->iov_base, 0, iov->iov_len);
}
@ -1155,8 +1190,11 @@ static int coroutine_fn qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset,
acb->cur_cluster = offset;
qemu_iovec_concat(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len);
/* Do the actual write */
return qed_aio_write_main(acb);
/* Do the actual write. */
r = qed_aio_write_main(acb);
out:
qemu_co_mutex_lock(&s->table_lock);
return r;
}
/**
@ -1166,6 +1204,8 @@ static int coroutine_fn qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset,
* @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2 or QED_CLUSTER_L1
* @offset: Cluster offset in bytes
* @len: Length in bytes
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_write_data(void *opaque, int ret,
uint64_t offset, size_t len)
@ -1197,6 +1237,8 @@ static int coroutine_fn qed_aio_write_data(void *opaque, int ret,
* @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2 or QED_CLUSTER_L1
* @offset: Cluster offset in bytes
* @len: Length in bytes
*
* Called with table_lock held.
*/
static int coroutine_fn qed_aio_read_data(void *opaque, int ret,
uint64_t offset, size_t len)
@ -1204,6 +1246,9 @@ static int coroutine_fn qed_aio_read_data(void *opaque, int ret,
QEDAIOCB *acb = opaque;
BDRVQEDState *s = acb_to_s(acb);
BlockDriverState *bs = acb->bs;
int r;
qemu_co_mutex_unlock(&s->table_lock);
/* Adjust offset into cluster */
offset += qed_offset_into_cluster(s, acb->cur_pos);
@ -1212,22 +1257,23 @@ static int coroutine_fn qed_aio_read_data(void *opaque, int ret,
qemu_iovec_concat(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len);
/* Handle zero cluster and backing file reads */
/* Handle zero cluster and backing file reads, otherwise read
* data cluster directly.
*/
if (ret == QED_CLUSTER_ZERO) {
qemu_iovec_memset(&acb->cur_qiov, 0, 0, acb->cur_qiov.size);
return 0;
r = 0;
} else if (ret != QED_CLUSTER_FOUND) {
return qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
&acb->backing_qiov);
r = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
&acb->backing_qiov);
} else {
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
r = bdrv_co_preadv(bs->file, offset, acb->cur_qiov.size,
&acb->cur_qiov, 0);
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
ret = bdrv_co_preadv(bs->file, offset, acb->cur_qiov.size,
&acb->cur_qiov, 0);
if (ret < 0) {
return ret;
}
return 0;
qemu_co_mutex_lock(&s->table_lock);
return r;
}
/**
@ -1240,6 +1286,7 @@ static int coroutine_fn qed_aio_next_io(QEDAIOCB *acb)
size_t len;
int ret;
qemu_co_mutex_lock(&s->table_lock);
while (1) {
trace_qed_aio_next_io(s, acb, 0, acb->cur_pos + acb->cur_qiov.size);
@ -1279,6 +1326,7 @@ static int coroutine_fn qed_aio_next_io(QEDAIOCB *acb)
trace_qed_aio_complete(s, acb, ret);
qed_aio_complete(acb);
qemu_co_mutex_unlock(&s->table_lock);
return ret;
}
@ -1474,8 +1522,14 @@ static void bdrv_qed_invalidate_cache(BlockDriverState *bs, Error **errp)
bdrv_qed_close(bs);
memset(s, 0, sizeof(BDRVQEDState));
bdrv_qed_init_state(bs);
if (qemu_in_coroutine()) {
qemu_co_mutex_lock(&s->table_lock);
}
ret = bdrv_qed_do_open(bs, NULL, bs->open_flags, &local_err);
if (qemu_in_coroutine()) {
qemu_co_mutex_unlock(&s->table_lock);
}
if (local_err) {
error_propagate(errp, local_err);
error_prepend(errp, "Could not reopen qed layer: ");
@ -1554,7 +1608,7 @@ static BlockDriver bdrv_qed = {
.bdrv_check = bdrv_qed_check,
.bdrv_detach_aio_context = bdrv_qed_detach_aio_context,
.bdrv_attach_aio_context = bdrv_qed_attach_aio_context,
.bdrv_drain = bdrv_qed_drain,
.bdrv_co_drain = bdrv_qed_co_drain,
};
static void bdrv_qed_init(void)

11
block/qed.h
View File

@ -151,15 +151,21 @@ typedef struct QEDAIOCB {
typedef struct {
BlockDriverState *bs; /* device */
uint64_t file_size; /* length of image file, in bytes */
/* Written only by an allocating write or the timer handler (the latter
* while allocating reqs are plugged).
*/
QEDHeader header; /* always cpu-endian */
/* Protected by table_lock. */
CoMutex table_lock;
QEDTable *l1_table;
L2TableCache l2_cache; /* l2 table cache */
uint32_t table_nelems;
uint32_t l1_shift;
uint32_t l2_shift;
uint32_t l2_mask;
uint64_t file_size; /* length of image file, in bytes */
/* Allocating write request queue */
QEDAIOCB *allocating_acb;
@ -177,9 +183,6 @@ enum {
QED_CLUSTER_L1, /* cluster missing in L1 */
};
void qed_acquire(BDRVQEDState *s);
void qed_release(BDRVQEDState *s);
/**
* Header functions
*/

21
block/sheepdog.c
View File

@ -390,6 +390,7 @@ struct BDRVSheepdogState {
QLIST_HEAD(inflight_aio_head, AIOReq) inflight_aio_head;
QLIST_HEAD(failed_aio_head, AIOReq) failed_aio_head;
CoMutex queue_lock;
CoQueue overlapping_queue;
QLIST_HEAD(inflight_aiocb_head, SheepdogAIOCB) inflight_aiocb_head;
};
@ -488,7 +489,7 @@ static void wait_for_overlapping_aiocb(BDRVSheepdogState *s, SheepdogAIOCB *acb)
retry:
QLIST_FOREACH(cb, &s->inflight_aiocb_head, aiocb_siblings) {
if (AIOCBOverlapping(acb, cb)) {
qemu_co_queue_wait(&s->overlapping_queue, NULL);
qemu_co_queue_wait(&s->overlapping_queue, &s->queue_lock);
goto retry;
}
}
@ -525,8 +526,10 @@ static void sd_aio_setup(SheepdogAIOCB *acb, BDRVSheepdogState *s,
return;
}
qemu_co_mutex_lock(&s->queue_lock);
wait_for_overlapping_aiocb(s, acb);
QLIST_INSERT_HEAD(&s->inflight_aiocb_head, acb, aiocb_siblings);
qemu_co_mutex_unlock(&s->queue_lock);
}
static SocketAddress *sd_socket_address(const char *path,
@ -785,6 +788,7 @@ static coroutine_fn void reconnect_to_sdog(void *opaque)
* have to move all the inflight requests to the failed queue before
* resend_aioreq() is called.
*/
qemu_co_mutex_lock(&s->queue_lock);
QLIST_FOREACH_SAFE(aio_req, &s->inflight_aio_head, aio_siblings, next) {
QLIST_REMOVE(aio_req, aio_siblings);
QLIST_INSERT_HEAD(&s->failed_aio_head, aio_req, aio_siblings);
@ -794,8 +798,11 @@ static coroutine_fn void reconnect_to_sdog(void *opaque)
while (!QLIST_EMPTY(&s->failed_aio_head)) {
aio_req = QLIST_FIRST(&s->failed_aio_head);
QLIST_REMOVE(aio_req, aio_siblings);
qemu_co_mutex_unlock(&s->queue_lock);
resend_aioreq(s, aio_req);
qemu_co_mutex_lock(&s->queue_lock);
}
qemu_co_mutex_unlock(&s->queue_lock);
}
/*
@ -887,7 +894,10 @@ static void coroutine_fn aio_read_response(void *opaque)
*/
s->co_recv = NULL;
qemu_co_mutex_lock(&s->queue_lock);
QLIST_REMOVE(aio_req, aio_siblings);
qemu_co_mutex_unlock(&s->queue_lock);
switch (rsp.result) {
case SD_RES_SUCCESS:
break;
@ -1307,7 +1317,9 @@ static void coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
uint64_t old_oid = aio_req->base_oid;
bool create = aio_req->create;
qemu_co_mutex_lock(&s->queue_lock);
QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
qemu_co_mutex_unlock(&s->queue_lock);
if (!nr_copies) {
error_report("bug");
@ -1678,6 +1690,7 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags,
bs->total_sectors = s->inode.vdi_size / BDRV_SECTOR_SIZE;
pstrcpy(s->name, sizeof(s->name), vdi);
qemu_co_mutex_init(&s->lock);
qemu_co_mutex_init(&s->queue_lock);
qemu_co_queue_init(&s->overlapping_queue);
qemu_opts_del(opts);
g_free(buf);
@ -2438,12 +2451,16 @@ static void coroutine_fn sd_co_rw_vector(SheepdogAIOCB *acb)
static void sd_aio_complete(SheepdogAIOCB *acb)
{
BDRVSheepdogState *s;
if (acb->aiocb_type == AIOCB_FLUSH_CACHE) {
return;
}
s = acb->s;
qemu_co_mutex_lock(&s->queue_lock);
QLIST_REMOVE(acb, aiocb_siblings);
qemu_co_queue_restart_all(&acb->s->overlapping_queue);
qemu_co_queue_restart_all(&s->overlapping_queue);
qemu_co_mutex_unlock(&s->queue_lock);
}
static coroutine_fn int sd_co_writev(BlockDriverState *bs, int64_t sector_num,

24
block/ssh.c
View File

@ -888,13 +888,22 @@ static int ssh_has_zero_init(BlockDriverState *bs)
return has_zero_init;
}
typedef struct BDRVSSHRestart {
BlockDriverState *bs;
Coroutine *co;
} BDRVSSHRestart;
static void restart_coroutine(void *opaque)
{
Coroutine *co = opaque;
BDRVSSHRestart *restart = opaque;
BlockDriverState *bs = restart->bs;
BDRVSSHState *s = bs->opaque;
AioContext *ctx = bdrv_get_aio_context(bs);
DPRINTF("co=%p", co);
DPRINTF("co=%p", restart->co);
aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL);
aio_co_wake(co);
aio_co_wake(restart->co);
}
/* A non-blocking call returned EAGAIN, so yield, ensuring the
@ -905,7 +914,10 @@ static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
{
int r;
IOHandler *rd_handler = NULL, *wr_handler = NULL;
Coroutine *co = qemu_coroutine_self();
BDRVSSHRestart restart = {
.bs = bs,
.co = qemu_coroutine_self()
};
r = libssh2_session_block_directions(s->session);
@ -920,11 +932,9 @@ static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
rd_handler, wr_handler);
aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
false, rd_handler, wr_handler, NULL, co);
false, rd_handler, wr_handler, NULL, &restart);
qemu_coroutine_yield();
DPRINTF("s->sock=%d - back", s->sock);
aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, false,
NULL, NULL, NULL, NULL);
}
/* SFTP has a function `libssh2_sftp_seek64' which seeks to a position

48
block/vdi.c
View File

@ -172,7 +172,7 @@ typedef struct {
/* VDI header (converted to host endianness). */
VdiHeader header;
CoMutex write_lock;
CoRwlock bmap_lock;
Error *migration_blocker;
} BDRVVdiState;
@ -485,7 +485,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
goto fail_free_bmap;
}
qemu_co_mutex_init(&s->write_lock);
qemu_co_rwlock_init(&s->bmap_lock);
return 0;
@ -557,7 +557,9 @@ vdi_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
n_bytes, offset);
/* prepare next AIO request */
qemu_co_rwlock_rdlock(&s->bmap_lock);
bmap_entry = le32_to_cpu(s->bmap[block_index]);
qemu_co_rwlock_unlock(&s->bmap_lock);
if (!VDI_IS_ALLOCATED(bmap_entry)) {
/* Block not allocated, return zeros, no need to wait. */
qemu_iovec_memset(qiov, bytes_done, 0, n_bytes);
@ -595,6 +597,7 @@ vdi_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
uint32_t block_index;
uint32_t offset_in_block;
uint32_t n_bytes;
uint64_t data_offset;
uint32_t bmap_first = VDI_UNALLOCATED;
uint32_t bmap_last = VDI_UNALLOCATED;
uint8_t *block = NULL;
@ -614,10 +617,19 @@ vdi_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
n_bytes, offset);
/* prepare next AIO request */
qemu_co_rwlock_rdlock(&s->bmap_lock);
bmap_entry = le32_to_cpu(s->bmap[block_index]);
if (!VDI_IS_ALLOCATED(bmap_entry)) {
/* Allocate new block and write to it. */
uint64_t data_offset;
qemu_co_rwlock_upgrade(&s->bmap_lock);
bmap_entry = le32_to_cpu(s->bmap[block_index]);
if (VDI_IS_ALLOCATED(bmap_entry)) {
/* A concurrent allocation did the work for us. */
qemu_co_rwlock_downgrade(&s->bmap_lock);
goto nonallocating_write;
}
bmap_entry = s->header.blocks_allocated;
s->bmap[block_index] = cpu_to_le32(bmap_entry);
s->header.blocks_allocated++;
@ -635,30 +647,18 @@ vdi_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
memset(block + offset_in_block + n_bytes, 0,
s->block_size - n_bytes - offset_in_block);
/* Note that this coroutine does not yield anywhere from reading the
* bmap entry until here, so in regards to all the coroutines trying
* to write to this cluster, the one doing the allocation will
* always be the first to try to acquire the lock.
* Therefore, it is also the first that will actually be able to
* acquire the lock and thus the padded cluster is written before
* the other coroutines can write to the affected area. */
qemu_co_mutex_lock(&s->write_lock);
/* Write the new block under CoRwLock write-side protection,
* so this full-cluster write does not overlap a partial write
* of the same cluster, issued from the "else" branch.
*/
ret = bdrv_pwrite(bs->file, data_offset, block, s->block_size);
qemu_co_mutex_unlock(&s->write_lock);
qemu_co_rwlock_unlock(&s->bmap_lock);
} else {
uint64_t data_offset = s->header.offset_data +
(uint64_t)bmap_entry * s->block_size +
offset_in_block;
qemu_co_mutex_lock(&s->write_lock);
/* This lock is only used to make sure the following write operation
* is executed after the write issued by the coroutine allocating
* this cluster, therefore we do not need to keep it locked.
* As stated above, the allocating coroutine will always try to lock
* the mutex before all the other concurrent accesses to that
* cluster, therefore at this point we can be absolutely certain
* that that write operation has returned (there may be other writes
* in flight, but they do not concern this very operation). */
qemu_co_mutex_unlock(&s->write_lock);
nonallocating_write:
data_offset = s->header.offset_data +
(uint64_t)bmap_entry * s->block_size +
offset_in_block;
qemu_co_rwlock_unlock(&s->bmap_lock);
qemu_iovec_reset(&local_qiov);
qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);

20
block/vpc.c
View File

@ -496,12 +496,6 @@ static inline int64_t get_image_offset(BlockDriverState *bs, uint64_t offset,
return block_offset;
}
static inline int64_t get_sector_offset(BlockDriverState *bs,
int64_t sector_num, bool write)
{
return get_image_offset(bs, sector_num * BDRV_SECTOR_SIZE, write);
}
/*
* Writes the footer to the end of the image file. This is needed when the
* file grows as it overwrites the old footer
@ -696,6 +690,7 @@ static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
VHDFooter *footer = (VHDFooter*) s->footer_buf;
int64_t start, offset;
bool allocated;
int64_t ret;
int n;
if (be32_to_cpu(footer->type) == VHD_FIXED) {
@ -705,10 +700,13 @@ static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
(sector_num << BDRV_SECTOR_BITS);
}
offset = get_sector_offset(bs, sector_num, 0);
qemu_co_mutex_lock(&s->lock);
offset = get_image_offset(bs, sector_num << BDRV_SECTOR_BITS, false);
start = offset;
allocated = (offset != -1);
*pnum = 0;
ret = 0;
do {
/* All sectors in a block are contiguous (without using the bitmap) */
@ -723,15 +721,17 @@ static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
* sectors since there is always a bitmap in between. */
if (allocated) {
*file = bs->file->bs;
return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
ret = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
break;
}
if (nb_sectors == 0) {
break;
}
offset = get_sector_offset(bs, sector_num, 0);
offset = get_image_offset(bs, sector_num << BDRV_SECTOR_BITS, false);
} while (offset == -1);
return 0;
qemu_co_mutex_unlock(&s->lock);
return ret;
}
/*

8
block/vvfat.c
View File

@ -3078,8 +3078,14 @@ static int coroutine_fn
write_target_commit(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
int ret;
BDRVVVFATState* s = *((BDRVVVFATState**) bs->opaque);
return try_commit(s);
qemu_co_mutex_lock(&s->lock);
ret = try_commit(s);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static void write_target_close(BlockDriverState *bs) {

2
include/block/block_int.h
View File

@ -324,7 +324,7 @@ struct BlockDriver {
* Drain and stop any internal sources of requests in the driver, and
* remain so until next I/O callback (e.g. bdrv_co_writev) is called.
*/
void (*bdrv_drain)(BlockDriverState *bs);
void coroutine_fn (*bdrv_co_drain)(BlockDriverState *bs);
void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
Error **errp);

18
include/qemu/coroutine.h
View File

@ -228,6 +228,24 @@ void qemu_co_rwlock_init(CoRwlock *lock);
*/
void qemu_co_rwlock_rdlock(CoRwlock *lock);
/**
* Write Locks the CoRwlock from a reader. This is a bit more efficient than
* @qemu_co_rwlock_unlock followed by a separate @qemu_co_rwlock_wrlock.
* However, if the lock cannot be upgraded immediately, control is transferred
* to the caller of the current coroutine. Also, @qemu_co_rwlock_upgrade
* only overrides CoRwlock fairness if there are no concurrent readers, so
* another writer might run while @qemu_co_rwlock_upgrade blocks.
*/
void qemu_co_rwlock_upgrade(CoRwlock *lock);
/**
* Downgrades a write-side critical section to a reader. Downgrading with
* @qemu_co_rwlock_downgrade never blocks, unlike @qemu_co_rwlock_unlock
* followed by @qemu_co_rwlock_rdlock. This makes it more efficient, but
* may also sometimes be necessary for correctness.
*/
void qemu_co_rwlock_downgrade(CoRwlock *lock);
/**
* Write Locks the mutex. If the lock cannot be taken immediately because
* of a parallel reader, control is transferred to the caller of the current

5
tests/docker/Makefile.include
View File

@ -106,6 +106,8 @@ docker:
@echo ' (default is 1)'
@echo ' DEBUG=1 Stop and drop to shell in the created container'
@echo ' before running the command.'
@echo ' NETWORK=1 Enable virtual network interface with default backend.'
@echo ' NETWORK=$BACKEND Enable virtual network interface with $BACKEND.'
@echo ' NOUSER Define to disable adding current user to containers passwd.'
@echo ' NOCACHE=1 Ignore cache when build images.'
@echo ' EXECUTABLE=<path> Include executable in image.'
@ -132,7 +134,8 @@ docker-run: docker-qemu-src
$(SRC_PATH)/tests/docker/docker.py run \
$(if $(NOUSER),,-u $(shell id -u)) -t \
$(if $V,,--rm) \
$(if $(DEBUG),-i,--net=none) \
$(if $(DEBUG),-i,) \
$(if $(NETWORK),$(if $(subst $(NETWORK),,1),--net=$(NETWORK)),--net=none) \
-e TARGET_LIST=$(TARGET_LIST) \
-e EXTRA_CONFIGURE_OPTS="$(EXTRA_CONFIGURE_OPTS)" \
-e V=$V -e J=$J -e DEBUG=$(DEBUG) \

23
tests/docker/docker.py
View File

@ -112,13 +112,16 @@ class Docker(object):
signal.signal(signal.SIGTERM, self._kill_instances)
signal.signal(signal.SIGHUP, self._kill_instances)
def _do(self, cmd, quiet=True, infile=None, **kwargs):
def _do(self, cmd, quiet=True, **kwargs):
if quiet:
kwargs["stdout"] = DEVNULL
if infile:
kwargs["stdin"] = infile
return subprocess.call(self._command + cmd, **kwargs)
def _do_check(self, cmd, quiet=True, **kwargs):
if quiet:
kwargs["stdout"] = DEVNULL
return subprocess.check_call(self._command + cmd, **kwargs)
def _do_kill_instances(self, only_known, only_active=True):
cmd = ["ps", "-q"]
if not only_active:
@ -177,14 +180,14 @@ class Docker(object):
extra_files_cksum)))
tmp_df.flush()
self._do(["build", "-t", tag, "-f", tmp_df.name] + argv + \
[docker_dir],
quiet=quiet)
self._do_check(["build", "-t", tag, "-f", tmp_df.name] + argv + \
[docker_dir],
quiet=quiet)
def update_image(self, tag, tarball, quiet=True):
"Update a tagged image using "
self._do(["build", "-t", tag, "-"], quiet=quiet, infile=tarball)
self._do_check(["build", "-t", tag, "-"], quiet=quiet, stdin=tarball)
def image_matches_dockerfile(self, tag, dockerfile):
try:
@ -197,9 +200,9 @@ class Docker(object):
label = uuid.uuid1().hex
if not keep:
self._instances.append(label)
ret = self._do(["run", "--label",
"com.qemu.instance.uuid=" + label] + cmd,
quiet=quiet)
ret = self._do_check(["run", "--label",
"com.qemu.instance.uuid=" + label] + cmd,
quiet=quiet)
if not keep:
self._instances.remove(label)
return ret

35
util/qemu-coroutine-lock.c
View File

@ -402,6 +402,21 @@ void qemu_co_rwlock_unlock(CoRwlock *lock)
qemu_co_mutex_unlock(&lock->mutex);
}
void qemu_co_rwlock_downgrade(CoRwlock *lock)
{
Coroutine *self = qemu_coroutine_self();
/* lock->mutex critical section started in qemu_co_rwlock_wrlock or
* qemu_co_rwlock_upgrade.
*/
assert(lock->reader == 0);
lock->reader++;
qemu_co_mutex_unlock(&lock->mutex);
/* The rest of the read-side critical section is run without the mutex. */
self->locks_held++;
}
void qemu_co_rwlock_wrlock(CoRwlock *lock)
{
qemu_co_mutex_lock(&lock->mutex);
@ -416,3 +431,23 @@ void qemu_co_rwlock_wrlock(CoRwlock *lock)
* There is no need to update self->locks_held.
*/
}
void qemu_co_rwlock_upgrade(CoRwlock *lock)
{
Coroutine *self = qemu_coroutine_self();
qemu_co_mutex_lock(&lock->mutex);
assert(lock->reader > 0);
lock->reader--;
lock->pending_writer++;
while (lock->reader) {
qemu_co_queue_wait(&lock->queue, &lock->mutex);
}
lock->pending_writer--;
/* The rest of the write-side critical section is run with
* the mutex taken, similar to qemu_co_rwlock_wrlock. Do
* not account for the lock twice in self->locks_held.
*/
self->locks_held--;
}