Merge remote-tracking branch 'remotes/vsementsov/tags/pull-jobs-2021-06-25' into staging

block: Make block-copy API thread-safe

# gpg: Signature made Fri 25 Jun 2021 13:40:24 BST
# gpg:                using RSA key 8B9C26CDB2FD147C880E86A1561F24C1F19F79FB
# gpg: Good signature from "Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>" [unknown]
# 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: 8B9C 26CD B2FD 147C 880E  86A1 561F 24C1 F19F 79FB

* remotes/vsementsov/tags/pull-jobs-2021-06-25:
  block-copy: atomic .cancelled and .finished fields in BlockCopyCallState
  block-copy: add CoMutex lock
  block-copy: move progress_set_remaining in block_copy_task_end
  block-copy: streamline choice of copy_range vs. read/write
  block-copy: small refactor in block_copy_task_entry and block_copy_common
  co-shared-resource: protect with a mutex
  progressmeter: protect with a mutex
  blockjob: let ratelimit handle a speed of 0
  block-copy: let ratelimit handle a speed of 0
  ratelimit: treat zero speed as unlimited

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 19 insertions, 5 deletions

diff --git a/util/qemu-co-shared-resource.c b/util/qemu-co-shared-resource.c
index 1c83cd9d29..a66cc07e75 100644
--- a/util/qemu-co-shared-resource.c
+++ b/util/qemu-co-shared-resource.c
@@ -28,10 +28,13 @@
 #include "qemu/co-shared-resource.h"
 
 struct SharedResource {
-    uint64_t total;
-    uint64_t available;
+    uint64_t total; /* Set in shres_create() and not changed anymore */
 
+    /* State fields protected by lock */
+    uint64_t available;
     CoQueue queue;
+
+    QemuMutex lock;
 };
 
 SharedResource *shres_create(uint64_t total)
@@ -40,6 +43,7 @@ SharedResource *shres_create(uint64_t total)
 
     s->total = s->available = total;
     qemu_co_queue_init(&s->queue);
+    qemu_mutex_init(&s->lock);
 
     return s;
 }
@@ -47,10 +51,12 @@ SharedResource *shres_create(uint64_t total)
 void shres_destroy(SharedResource *s)
 {
     assert(s->available == s->total);
+    qemu_mutex_destroy(&s->lock);
     g_free(s);
 }
 
-bool co_try_get_from_shres(SharedResource *s, uint64_t n)
+/* Called with lock held. */
+static bool co_try_get_from_shres_locked(SharedResource *s, uint64_t n)
 {
     if (s->available >= n) {
         s->available -= n;
@@ -60,16 +66,24 @@ bool co_try_get_from_shres(SharedResource *s, uint64_t n)
     return false;
 }
 
+bool co_try_get_from_shres(SharedResource *s, uint64_t n)
+{
+    QEMU_LOCK_GUARD(&s->lock);
+    return co_try_get_from_shres_locked(s, n);
+}
+
 void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n)
 {
     assert(n <= s->total);
-    while (!co_try_get_from_shres(s, n)) {
-        qemu_co_queue_wait(&s->queue, NULL);
+    QEMU_LOCK_GUARD(&s->lock);
+    while (!co_try_get_from_shres_locked(s, n)) {
+        qemu_co_queue_wait(&s->queue, &s->lock);
     }
 }
 
 void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n)
 {
+    QEMU_LOCK_GUARD(&s->lock);
     assert(s->total - s->available >= n);
     s->available += n;
     qemu_co_queue_restart_all(&s->queue);