Merge remote-tracking branch 'remotes/stefanha-gitlab/tags/block-pull-request' into staging

Pull request

(Resent due to an email preparation mistake.)

# gpg: Signature made Mon 24 May 2021 14:01:42 BST
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha-gitlab/tags/block-pull-request:
  coroutine-sleep: introduce qemu_co_sleep
  coroutine-sleep: replace QemuCoSleepState pointer with struct in the API
  coroutine-sleep: move timer out of QemuCoSleepState
  coroutine-sleep: allow qemu_co_sleep_wake that wakes nothing
  coroutine-sleep: disallow NULL QemuCoSleepState** argument
  coroutine-sleep: use a stack-allocated timer
  bitops.h: Improve find_xxx_bit() documentation
  multi-process: Initialize variables declared with g_auto*

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

7 files changed, 79 insertions, 70 deletions

diff --git a/block/block-copy.c b/block/block-copy.c
index 9b4af00614..c2e5090412 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -50,7 +50,7 @@ typedef struct BlockCopyCallState {
     /* State */
     int ret;
     bool finished;
-    QemuCoSleepState *sleep_state;
+    QemuCoSleep sleep;
     bool cancelled;
 
     /* OUT parameters */
@@ -625,8 +625,8 @@ block_copy_dirty_clusters(BlockCopyCallState *call_state)
                 if (ns > 0) {
                     block_copy_task_end(task, -EAGAIN);
                     g_free(task);
-                    qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, ns,
-                                              &call_state->sleep_state);
+                    qemu_co_sleep_ns_wakeable(&call_state->sleep,
+                                              QEMU_CLOCK_REALTIME, ns);
                     continue;
                 }
             }
@@ -674,9 +674,7 @@ out:
 
 void block_copy_kick(BlockCopyCallState *call_state)
 {
-    if (call_state->sleep_state) {
-        qemu_co_sleep_wake(call_state->sleep_state);
-    }
+    qemu_co_sleep_wake(&call_state->sleep);
 }
 
 /*
diff --git a/block/nbd.c b/block/nbd.c
index 1d4668d42d..616f9ae6c4 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -116,7 +116,7 @@ typedef struct BDRVNBDState {
     CoQueue free_sema;
     Coroutine *connection_co;
     Coroutine *teardown_co;
-    QemuCoSleepState *connection_co_sleep_ns_state;
+    QemuCoSleep reconnect_sleep;
     bool drained;
     bool wait_drained_end;
     int in_flight;
@@ -289,9 +289,7 @@ static void coroutine_fn nbd_client_co_drain_begin(BlockDriverState *bs)
     BDRVNBDState *s = (BDRVNBDState *)bs->opaque;
 
     s->drained = true;
-    if (s->connection_co_sleep_ns_state) {
-        qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
-    }
+    qemu_co_sleep_wake(&s->reconnect_sleep);
 
     nbd_co_establish_connection_cancel(bs, false);
 
@@ -330,9 +328,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
 
     s->state = NBD_CLIENT_QUIT;
     if (s->connection_co) {
-        if (s->connection_co_sleep_ns_state) {
-            qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
-        }
+        qemu_co_sleep_wake(&s->reconnect_sleep);
         nbd_co_establish_connection_cancel(bs, true);
     }
     if (qemu_in_coroutine()) {
@@ -689,8 +685,8 @@ static coroutine_fn void nbd_co_reconnect_loop(BDRVNBDState *s)
             }
             bdrv_inc_in_flight(s->bs);
         } else {
-            qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, timeout,
-                                      &s->connection_co_sleep_ns_state);
+            qemu_co_sleep_ns_wakeable(&s->reconnect_sleep,
+                                      QEMU_CLOCK_REALTIME, timeout);
             if (s->drained) {
                 continue;
             }
diff --git a/hw/remote/memory.c b/hw/remote/memory.c
index 2d4174614a..472ed2a272 100644
--- a/hw/remote/memory.c
+++ b/hw/remote/memory.c
@@ -41,10 +41,9 @@ void remote_sysmem_reconfig(MPQemuMsg *msg, Error **errp)
 
     remote_sysmem_reset();
 
-    for (region = 0; region < msg->num_fds; region++) {
-        g_autofree char *name;
+    for (region = 0; region < msg->num_fds; region++, suffix++) {
+        g_autofree char *name = g_strdup_printf("remote-mem-%u", suffix);
         subregion = g_new(MemoryRegion, 1);
-        name = g_strdup_printf("remote-mem-%u", suffix++);
         memory_region_init_ram_from_fd(subregion, NULL,
                                        name, sysmem_info->sizes[region],
                                        true, msg->fds[region],
diff --git a/hw/remote/proxy.c b/hw/remote/proxy.c
index 4fa4be079d..6dda705fc2 100644
--- a/hw/remote/proxy.c
+++ b/hw/remote/proxy.c
@@ -347,13 +347,12 @@ static void probe_pci_info(PCIDevice *dev, Error **errp)
                    PCI_BASE_ADDRESS_SPACE_IO : PCI_BASE_ADDRESS_SPACE_MEMORY;
 
         if (size) {
-            g_autofree char *name;
+            g_autofree char *name = g_strdup_printf("bar-region-%d", i);
             pdev->region[i].dev = pdev;
             pdev->region[i].present = true;
             if (type == PCI_BASE_ADDRESS_SPACE_MEMORY) {
                 pdev->region[i].memory = true;
             }
-            name = g_strdup_printf("bar-region-%d", i);
             memory_region_init_io(&pdev->region[i].mr, OBJECT(pdev),
                                   &proxy_mr_ops, &pdev->region[i],
                                   name, size);
diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
index 3acbf3384c..a72f69fea8 100644
--- a/include/qemu/bitops.h
+++ b/include/qemu/bitops.h
@@ -140,7 +140,8 @@ static inline int test_bit(long nr, const unsigned long *addr)
  * @addr: The address to start the search at
  * @size: The maximum size to search
  *
- * Returns the bit number of the first set bit, or size.
+ * Returns the bit number of the last set bit,
+ * or @size if there is no set bit in the bitmap.
  */
 unsigned long find_last_bit(const unsigned long *addr,
                             unsigned long size);
@@ -150,6 +151,9 @@ unsigned long find_last_bit(const unsigned long *addr,
  * @addr: The address to base the search on
  * @offset: The bitnumber to start searching at
  * @size: The bitmap size in bits
+ *
+ * Returns the bit number of the next set bit,
+ * or @size if there are no further set bits in the bitmap.
  */
 unsigned long find_next_bit(const unsigned long *addr,
                             unsigned long size,
@@ -160,6 +164,9 @@ unsigned long find_next_bit(const unsigned long *addr,
  * @addr: The address to base the search on
  * @offset: The bitnumber to start searching at
  * @size: The bitmap size in bits
+ *
+ * Returns the bit number of the next cleared bit,
+ * or @size if there are no further clear bits in the bitmap.
  */
 
 unsigned long find_next_zero_bit(const unsigned long *addr,
@@ -171,7 +178,8 @@ unsigned long find_next_zero_bit(const unsigned long *addr,
  * @addr: The address to start the search at
  * @size: The maximum size to search
  *
- * Returns the bit number of the first set bit.
+ * Returns the bit number of the first set bit,
+ * or @size if there is no set bit in the bitmap.
  */
 static inline unsigned long find_first_bit(const unsigned long *addr,
                                            unsigned long size)
@@ -194,7 +202,8 @@ static inline unsigned long find_first_bit(const unsigned long *addr,
  * @addr: The address to start the search at
  * @size: The maximum size to search
  *
- * Returns the bit number of the first cleared bit.
+ * Returns the bit number of the first cleared bit,
+ * or @size if there is no clear bit in the bitmap.
  */
 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
                                                 unsigned long size)
diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h
index ce5b9c6851..292e61aef0 100644
--- a/include/qemu/coroutine.h
+++ b/include/qemu/coroutine.h
@@ -291,20 +291,27 @@ void qemu_co_rwlock_wrlock(CoRwlock *lock);
  */
 void qemu_co_rwlock_unlock(CoRwlock *lock);
 
-typedef struct QemuCoSleepState QemuCoSleepState;
+typedef struct QemuCoSleep {
+    Coroutine *to_wake;
+} QemuCoSleep;
 
 /**
- * Yield the coroutine for a given duration. During this yield, @sleep_state
- * (if not NULL) is set to an opaque pointer, which may be used for
- * qemu_co_sleep_wake(). Be careful, the pointer is set back to zero when the
- * timer fires. Don't save the obtained value to other variables and don't call
- * qemu_co_sleep_wake from another aio context.
+ * Yield the coroutine for a given duration. Initializes @w so that,
+ * during this yield, it can be passed to qemu_co_sleep_wake() to
+ * terminate the sleep.
  */
-void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
-                                            QemuCoSleepState **sleep_state);
+void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
+                                            QEMUClockType type, int64_t ns);
+
+/**
+ * Yield the coroutine until the next call to qemu_co_sleep_wake.
+ */
+void coroutine_fn qemu_co_sleep(QemuCoSleep *w);
+
 static inline void coroutine_fn qemu_co_sleep_ns(QEMUClockType type, int64_t ns)
 {
-    qemu_co_sleep_ns_wakeable(type, ns, NULL);
+    QemuCoSleep w = { 0 };
+    qemu_co_sleep_ns_wakeable(&w, type, ns);
 }
 
 /**
@@ -313,7 +320,7 @@ static inline void coroutine_fn qemu_co_sleep_ns(QEMUClockType type, int64_t ns)
  * qemu_co_sleep_ns() and should be checked to be non-NULL before calling
  * qemu_co_sleep_wake().
  */
-void qemu_co_sleep_wake(QemuCoSleepState *sleep_state);
+void qemu_co_sleep_wake(QemuCoSleep *w);
 
 /**
  * Yield until a file descriptor becomes readable
diff --git a/util/qemu-coroutine-sleep.c b/util/qemu-coroutine-sleep.c
index 8c4dac4fd7..571ab521ff 100644
--- a/util/qemu-coroutine-sleep.c
+++ b/util/qemu-coroutine-sleep.c
@@ -19,43 +19,34 @@
 
 static const char *qemu_co_sleep_ns__scheduled = "qemu_co_sleep_ns";
 
-struct QemuCoSleepState {
+void qemu_co_sleep_wake(QemuCoSleep *w)
+{
     Coroutine *co;
-    QEMUTimer *ts;
-    QemuCoSleepState **user_state_pointer;
-};
 
-void qemu_co_sleep_wake(QemuCoSleepState *sleep_state)
-{
-    /* Write of schedule protected by barrier write in aio_co_schedule */
-    const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled,
-                                           qemu_co_sleep_ns__scheduled, NULL);
+    co = w->to_wake;
+    w->to_wake = NULL;
+    if (co) {
+        /* Write of schedule protected by barrier write in aio_co_schedule */
+        const char *scheduled = qatomic_cmpxchg(&co->scheduled,
+                                                qemu_co_sleep_ns__scheduled, NULL);
 
-    assert(scheduled == qemu_co_sleep_ns__scheduled);
-    if (sleep_state->user_state_pointer) {
-        *sleep_state->user_state_pointer = NULL;
+        assert(scheduled == qemu_co_sleep_ns__scheduled);
+        aio_co_wake(co);
     }
-    timer_del(sleep_state->ts);
-    aio_co_wake(sleep_state->co);
 }
 
 static void co_sleep_cb(void *opaque)
 {
-    qemu_co_sleep_wake(opaque);
+    QemuCoSleep *w = opaque;
+    qemu_co_sleep_wake(w);
 }
 
-void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
-                                            QemuCoSleepState **sleep_state)
+void coroutine_fn qemu_co_sleep(QemuCoSleep *w)
 {
-    AioContext *ctx = qemu_get_current_aio_context();
-    QemuCoSleepState state = {
-        .co = qemu_coroutine_self(),
-        .ts = aio_timer_new(ctx, type, SCALE_NS, co_sleep_cb, &state),
-        .user_state_pointer = sleep_state,
-    };
+    Coroutine *co = qemu_coroutine_self();
 
-    const char *scheduled = qatomic_cmpxchg(&state.co->scheduled, NULL,
-                                           qemu_co_sleep_ns__scheduled);
+    const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
+                                            qemu_co_sleep_ns__scheduled);
     if (scheduled) {
         fprintf(stderr,
                 "%s: Co-routine was already scheduled in '%s'\n",
@@ -63,17 +54,27 @@ void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
         abort();
     }
 
-    if (sleep_state) {
-        *sleep_state = &state;
-    }
-    timer_mod(state.ts, qemu_clock_get_ns(type) + ns);
+    w->to_wake = co;
     qemu_coroutine_yield();
-    if (sleep_state) {
-        /*
-         * Note that *sleep_state is cleared during qemu_co_sleep_wake
-         * before resuming this coroutine.
-         */
-        assert(*sleep_state == NULL);
-    }
-    timer_free(state.ts);
+
+    /* w->to_wake is cleared before resuming this coroutine.  */
+    assert(w->to_wake == NULL);
+}
+
+void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
+                                            QEMUClockType type, int64_t ns)
+{
+    AioContext *ctx = qemu_get_current_aio_context();
+    QEMUTimer ts;
+
+    aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w);
+    timer_mod(&ts, qemu_clock_get_ns(type) + ns);
+
+    /*
+     * The timer will fire in the current AiOContext, so the callback
+     * must happen after qemu_co_sleep yields and there is no race
+     * between timer_mod and qemu_co_sleep.
+     */
+    qemu_co_sleep(w);
+    timer_del(&ts);
 }