Pull request

-----BEGIN PGP SIGNATURE-----
 
 iQEzBAABCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl7aFK8ACgkQnKSrs4Gr
 c8gocQf9G0xxCGrh99I7BAOoiA52vTl9sSjwVzIFzmzHSCnAGaERY+wSfuipILsz
 0/DlD0KBcQqwEkIGRJ9iNJgQIkOGc5MTlgNQojjFkBuM4eHiv+Ow+TomIAOEZnmL
 qJ2rslk/bHjKpOXjiXfa5SiLcPi2z8nJkTkRo3p9sg+iVJRAQsIydBK+LZc+iInD
 CvWsOYgGySqw5CH3h+S4Kt5WBcgxiaHzUqt+kXgMqjkKewHndIKKJavHaR3+GdrN
 kG3lTDLuDZ4CCs9o0VZxKVW10VrH8RYjuF9VdRVg0KJCp24v2+o7WiiPF5DRZ/7t
 QbYZjfovdQB6jhy5HXM4RXzsOp1HIg==
 =/HM9
 -----END PGP SIGNATURE-----

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

Pull request

# gpg: Signature made Fri 05 Jun 2020 10:47:27 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/tags/block-pull-request:
  block: Factor out bdrv_run_co()
  exec: Rename qemu_ram_writeback() as qemu_ram_msync()
  hw/block: Let the NVMe emulated device be target-agnostic
  memory: Extract memory_region_msync() from memory_region_writeback()
  memory: Rename memory_region_do_writeback -> memory_region_writeback
  fuzz: run the main-loop in fork-server process
  fuzz: add mangled object name to linker script
  fuzz: fix typo in i440fx-qtest-reboot arguments
  fuzz: add datadir for oss-fuzz compatability
  io_uring: use io_uring_cq_ready() to check for ready cqes
  io_uring: retry io_uring_submit() if it fails with errno=EINTR

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

block/io.c

@@ -35,8 +35,6 @@
 #include "qemu/main-loop.h"
 #include "sysemu/replay.h"
 
-#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
-
 /* Maximum bounce buffer for copy-on-read and write zeroes, in bytes */
 #define MAX_BOUNCE_BUFFER (32768 << BDRV_SECTOR_BITS)
 
@@ -891,29 +889,63 @@ static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
     return 0;
 }
 
+typedef int coroutine_fn BdrvRequestEntry(void *opaque);
+typedef struct BdrvRunCo {
+    BdrvRequestEntry *entry;
+    void *opaque;
+    int ret;
+    bool done;
+    Coroutine *co; /* Coroutine, running bdrv_run_co_entry, for debugging */
+} BdrvRunCo;
+
+static void coroutine_fn bdrv_run_co_entry(void *opaque)
+{
+    BdrvRunCo *arg = opaque;
+
+    arg->ret = arg->entry(arg->opaque);
+    arg->done = true;
+    aio_wait_kick();
+}
+
+static int bdrv_run_co(BlockDriverState *bs, BdrvRequestEntry *entry,
+                       void *opaque)
+{
+    if (qemu_in_coroutine()) {
+        /* Fast-path if already in coroutine context */
+        return entry(opaque);
+    } else {
+        BdrvRunCo s = { .entry = entry, .opaque = opaque };
+
+        s.co = qemu_coroutine_create(bdrv_run_co_entry, &s);
+        bdrv_coroutine_enter(bs, s.co);
+
+        BDRV_POLL_WHILE(bs, !s.done);
+
+        return s.ret;
+    }
+}
+
 typedef struct RwCo {
     BdrvChild *child;
     int64_t offset;
     QEMUIOVector *qiov;
     bool is_write;
-    int ret;
     BdrvRequestFlags flags;
 } RwCo;
 
-static void coroutine_fn bdrv_rw_co_entry(void *opaque)
+static int coroutine_fn bdrv_rw_co_entry(void *opaque)
 {
     RwCo *rwco = opaque;
 
     if (!rwco->is_write) {
-        rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset,
+        return bdrv_co_preadv(rwco->child, rwco->offset,
-                                   rwco->qiov->size, rwco->qiov,
+                              rwco->qiov->size, rwco->qiov,
-                                   rwco->flags);
+                              rwco->flags);
     } else {
-        rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset,
+        return bdrv_co_pwritev(rwco->child, rwco->offset,
-                                    rwco->qiov->size, rwco->qiov,
+                               rwco->qiov->size, rwco->qiov,
-                                    rwco->flags);
+                               rwco->flags);
     }
-    aio_wait_kick();
 }
 
 /*
@@ -923,25 +955,15 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
                         QEMUIOVector *qiov, bool is_write,
                         BdrvRequestFlags flags)
 {
-    Coroutine *co;
     RwCo rwco = {
         .child = child,
         .offset = offset,
         .qiov = qiov,
         .is_write = is_write,
-        .ret = NOT_DONE,
         .flags = flags,
     };
 
-    if (qemu_in_coroutine()) {
+    return bdrv_run_co(child->bs, bdrv_rw_co_entry, &rwco);
-        /* Fast-path if already in coroutine context */
-        bdrv_rw_co_entry(&rwco);
-    } else {
-        co = qemu_coroutine_create(bdrv_rw_co_entry, &rwco);
-        bdrv_coroutine_enter(child->bs, co);
-        BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
-    }
-    return rwco.ret;
 }
 
 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
@@ -2229,8 +2251,6 @@ typedef struct BdrvCoBlockStatusData {
     int64_t *pnum;
     int64_t *map;
     BlockDriverState **file;
-    int ret;
-    bool done;
 } BdrvCoBlockStatusData;
 
 int coroutine_fn bdrv_co_block_status_from_file(BlockDriverState *bs,
@@ -2484,16 +2504,14 @@ static int coroutine_fn bdrv_co_block_status_above(BlockDriverState *bs,
 }
 
 /* Coroutine wrapper for bdrv_block_status_above() */
-static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque)
+static int coroutine_fn bdrv_block_status_above_co_entry(void *opaque)
 {
     BdrvCoBlockStatusData *data = opaque;
 
-    data->ret = bdrv_co_block_status_above(data->bs, data->base,
+    return bdrv_co_block_status_above(data->bs, data->base,
-                                           data->want_zero,
+                                      data->want_zero,
-                                           data->offset, data->bytes,
+                                      data->offset, data->bytes,
-                                           data->pnum, data->map, data->file);
+                                      data->pnum, data->map, data->file);
-    data->done = true;
-    aio_wait_kick();
 }
 
 /*
@@ -2508,7 +2526,6 @@ static int bdrv_common_block_status_above(BlockDriverState *bs,
                                           int64_t *map,
                                           BlockDriverState **file)
 {
-    Coroutine *co;
     BdrvCoBlockStatusData data = {
         .bs = bs,
         .base = base,
@@ -2518,18 +2535,9 @@ static int bdrv_common_block_status_above(BlockDriverState *bs,
         .pnum = pnum,
         .map = map,
         .file = file,
-        .done = false,
     };
 
-    if (qemu_in_coroutine()) {
+    return bdrv_run_co(bs, bdrv_block_status_above_co_entry, &data);
-        /* Fast-path if already in coroutine context */
-        bdrv_block_status_above_co_entry(&data);
-    } else {
-        co = qemu_coroutine_create(bdrv_block_status_above_co_entry, &data);
-        bdrv_coroutine_enter(bs, co);
-        BDRV_POLL_WHILE(bs, !data.done);
-    }
-    return data.ret;
 }
 
 int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
@@ -2630,7 +2638,6 @@ typedef struct BdrvVmstateCo {
     QEMUIOVector        *qiov;
     int64_t             pos;
     bool                is_read;
-    int                 ret;
 } BdrvVmstateCo;
 
 static int coroutine_fn
@@ -2658,33 +2665,25 @@ bdrv_co_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
     return ret;
 }
 
-static void coroutine_fn bdrv_co_rw_vmstate_entry(void *opaque)
+static int coroutine_fn bdrv_co_rw_vmstate_entry(void *opaque)
 {
     BdrvVmstateCo *co = opaque;
-    co->ret = bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read);
+
-    aio_wait_kick();
+    return bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read);
 }
 
 static inline int
 bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
                 bool is_read)
 {
-    if (qemu_in_coroutine()) {
+    BdrvVmstateCo data = {
-        return bdrv_co_rw_vmstate(bs, qiov, pos, is_read);
+        .bs         = bs,
-    } else {
+        .qiov       = qiov,
-        BdrvVmstateCo data = {
+        .pos        = pos,
-            .bs         = bs,
+        .is_read    = is_read,
-            .qiov       = qiov,
+    };
-            .pos        = pos,
-            .is_read    = is_read,
-            .ret        = -EINPROGRESS,
-        };
-        Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry, &data);
 
-        bdrv_coroutine_enter(bs, co);
+    return bdrv_run_co(bs, bdrv_co_rw_vmstate_entry, &data);
-        BDRV_POLL_WHILE(bs, data.ret == -EINPROGRESS);
-        return data.ret;
-    }
 }
 
 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
@@ -2762,18 +2761,9 @@ void bdrv_aio_cancel_async(BlockAIOCB *acb)
 /**************************************************************/
 /* Coroutine block device emulation */
 
-typedef struct FlushCo {
+static int coroutine_fn bdrv_flush_co_entry(void *opaque)
-    BlockDriverState *bs;
-    int ret;
-} FlushCo;
-
-
-static void coroutine_fn bdrv_flush_co_entry(void *opaque)
 {
-    FlushCo *rwco = opaque;
+    return bdrv_co_flush(opaque);
-
-    rwco->ret = bdrv_co_flush(rwco->bs);
-    aio_wait_kick();
 }
 
 int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
@@ -2890,36 +2880,20 @@ early_exit:
 
 int bdrv_flush(BlockDriverState *bs)
 {
-    Coroutine *co;
+    return bdrv_run_co(bs, bdrv_flush_co_entry, bs);
-    FlushCo flush_co = {
-        .bs = bs,
-        .ret = NOT_DONE,
-    };
-
-    if (qemu_in_coroutine()) {
-        /* Fast-path if already in coroutine context */
-        bdrv_flush_co_entry(&flush_co);
-    } else {
-        co = qemu_coroutine_create(bdrv_flush_co_entry, &flush_co);
-        bdrv_coroutine_enter(bs, co);
-        BDRV_POLL_WHILE(bs, flush_co.ret == NOT_DONE);
-    }
-
-    return flush_co.ret;
 }
 
 typedef struct DiscardCo {
     BdrvChild *child;
     int64_t offset;
     int64_t bytes;
-    int ret;
 } DiscardCo;
-static void coroutine_fn bdrv_pdiscard_co_entry(void *opaque)
+
+static int coroutine_fn bdrv_pdiscard_co_entry(void *opaque)
 {
     DiscardCo *rwco = opaque;
 
-    rwco->ret = bdrv_co_pdiscard(rwco->child, rwco->offset, rwco->bytes);
+    return bdrv_co_pdiscard(rwco->child, rwco->offset, rwco->bytes);
-    aio_wait_kick();
 }
 
 int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
@@ -3038,24 +3012,13 @@ out:
 
 int bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes)
 {
-    Coroutine *co;
     DiscardCo rwco = {
         .child = child,
         .offset = offset,
         .bytes = bytes,
-        .ret = NOT_DONE,
     };
 
-    if (qemu_in_coroutine()) {
+    return bdrv_run_co(child->bs, bdrv_pdiscard_co_entry, &rwco);
-        /* Fast-path if already in coroutine context */
-        bdrv_pdiscard_co_entry(&rwco);
-    } else {
-        co = qemu_coroutine_create(bdrv_pdiscard_co_entry, &rwco);
-        bdrv_coroutine_enter(child->bs, co);
-        BDRV_POLL_WHILE(child->bs, rwco.ret == NOT_DONE);
-    }
-
-    return rwco.ret;
 }
 
 int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf)
@@ -3463,21 +3426,19 @@ typedef struct TruncateCo {
     PreallocMode prealloc;
     BdrvRequestFlags flags;
     Error **errp;
-    int ret;
 } TruncateCo;
 
-static void coroutine_fn bdrv_truncate_co_entry(void *opaque)
+static int coroutine_fn bdrv_truncate_co_entry(void *opaque)
 {
     TruncateCo *tco = opaque;
-    tco->ret = bdrv_co_truncate(tco->child, tco->offset, tco->exact,
+
-                                tco->prealloc, tco->flags, tco->errp);
+    return bdrv_co_truncate(tco->child, tco->offset, tco->exact,
-    aio_wait_kick();
+                            tco->prealloc, tco->flags, tco->errp);
 }
 
 int bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
                   PreallocMode prealloc, BdrvRequestFlags flags, Error **errp)
 {
-    Coroutine *co;
     TruncateCo tco = {
         .child      = child,
         .offset     = offset,
@@ -3485,17 +3446,7 @@ int bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
         .prealloc   = prealloc,
         .flags      = flags,
         .errp       = errp,
-        .ret        = NOT_DONE,
     };
 
-    if (qemu_in_coroutine()) {
+    return bdrv_run_co(child->bs, bdrv_truncate_co_entry, &tco);
-        /* Fast-path if already in coroutine context */
-        bdrv_truncate_co_entry(&tco);
-    } else {
-        co = qemu_coroutine_create(bdrv_truncate_co_entry, &tco);
-        bdrv_coroutine_enter(child->bs, co);
-        BDRV_POLL_WHILE(child->bs, tco.ret == NOT_DONE);
-    }
-
-    return tco.ret;
 }

block/io_uring.c

@@ -231,7 +231,7 @@ static int ioq_submit(LuringState *s)
         trace_luring_io_uring_submit(s, ret);
         /* Prevent infinite loop if submission is refused */
         if (ret <= 0) {
-            if (ret == -EAGAIN) {
+            if (ret == -EAGAIN || ret == -EINTR) {
                 continue;
             }
             break;
@@ -277,13 +277,10 @@ static void qemu_luring_completion_cb(void *opaque)
 static bool qemu_luring_poll_cb(void *opaque)
 {
     LuringState *s = opaque;
-    struct io_uring_cqe *cqes;
 
-    if (io_uring_peek_cqe(&s->ring, &cqes) == 0) {
+    if (io_uring_cq_ready(&s->ring)) {
-        if (cqes) {
+        luring_process_completions_and_submit(s);
-            luring_process_completions_and_submit(s);
+        return true;
-            return true;
-        }
     }
 
     return false;

exec.c

@@ -2127,7 +2127,7 @@ int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp)
  * Otherwise no-op.
  * @Note: this is supposed to be a synchronous op.
  */
-void qemu_ram_writeback(RAMBlock *block, ram_addr_t start, ram_addr_t length)
+void qemu_ram_msync(RAMBlock *block, ram_addr_t start, ram_addr_t length)
 {
     /* The requested range should fit in within the block range */
     g_assert((start + length) <= block->used_length);

hw/block/Makefile.objs

@@ -13,6 +13,6 @@ common-obj-$(CONFIG_SH4) += tc58128.o
 
 obj-$(CONFIG_VIRTIO_BLK) += virtio-blk.o
 obj-$(CONFIG_VHOST_USER_BLK) += vhost-user-blk.o
-obj-$(CONFIG_NVME_PCI) += nvme.o
+common-obj-$(CONFIG_NVME_PCI) += nvme.o
 
 obj-y += dataplane/

hw/block/nvme.c

@@ -46,8 +46,7 @@
 #include "qapi/visitor.h"
 #include "sysemu/hostmem.h"
 #include "sysemu/block-backend.h"
-#include "exec/ram_addr.h"
+#include "exec/memory.h"
-
 #include "qemu/log.h"
 #include "qemu/module.h"
 #include "qemu/cutils.h"
@@ -1207,8 +1206,7 @@ static uint64_t nvme_mmio_read(void *opaque, hwaddr addr, unsigned size)
          */
         if (addr == 0xE08 &&
             (NVME_PMRCAP_PMRWBM(n->bar.pmrcap) & 0x02)) {
-            qemu_ram_writeback(n->pmrdev->mr.ram_block,
+            memory_region_msync(&n->pmrdev->mr, 0, n->pmrdev->size);
-                               0, n->pmrdev->size);
         }
         memcpy(&val, ptr + addr, size);
     } else {

include/exec/memory.h

@@ -1473,15 +1473,26 @@ void *memory_region_get_ram_ptr(MemoryRegion *mr);
  */
 void memory_region_ram_resize(MemoryRegion *mr, ram_addr_t newsize,
                               Error **errp);
+
 /**
- * memory_region_do_writeback: Trigger cache writeback or msync for
+ * memory_region_msync: Synchronize selected address range of
+ * a memory mapped region
+ *
+ * @mr: the memory region to be msync
+ * @addr: the initial address of the range to be sync
+ * @size: the size of the range to be sync
+ */
+void memory_region_msync(MemoryRegion *mr, hwaddr addr, hwaddr size);
+
+/**
+ * memory_region_writeback: Trigger cache writeback for
  * selected address range
  *
  * @mr: the memory region to be updated
  * @addr: the initial address of the range to be written back
  * @size: the size of the range to be written back
  */
-void memory_region_do_writeback(MemoryRegion *mr, hwaddr addr, hwaddr size);
+void memory_region_writeback(MemoryRegion *mr, hwaddr addr, hwaddr size);
 
 /**
  * memory_region_set_log: Turn dirty logging on or off for a region.

include/exec/ram_addr.h

@@ -136,12 +136,12 @@ void qemu_ram_free(RAMBlock *block);
 
 int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp);
 
-void qemu_ram_writeback(RAMBlock *block, ram_addr_t start, ram_addr_t length);
+void qemu_ram_msync(RAMBlock *block, ram_addr_t start, ram_addr_t length);
 
 /* Clear whole block of mem */
 static inline void qemu_ram_block_writeback(RAMBlock *block)
 {
-    qemu_ram_writeback(block, 0, block->used_length);
+    qemu_ram_msync(block, 0, block->used_length);
 }
 
 #define DIRTY_CLIENTS_ALL     ((1 << DIRTY_MEMORY_NUM) - 1)

include/sysemu/sysemu.h

@@ -15,6 +15,8 @@ extern const char *qemu_name;
 extern QemuUUID qemu_uuid;
 extern bool qemu_uuid_set;
 
+void qemu_add_data_dir(const char *path);
+
 void qemu_add_exit_notifier(Notifier *notify);
 void qemu_remove_exit_notifier(Notifier *notify);
 

memory.c

@@ -2197,15 +2197,21 @@ void memory_region_ram_resize(MemoryRegion *mr, ram_addr_t newsize, Error **errp
     qemu_ram_resize(mr->ram_block, newsize, errp);
 }
 
+void memory_region_msync(MemoryRegion *mr, hwaddr addr, hwaddr size)
+{
+    if (mr->ram_block) {
+        qemu_ram_msync(mr->ram_block, addr, size);
+    }
+}
 
-void memory_region_do_writeback(MemoryRegion *mr, hwaddr addr, hwaddr size)
+void memory_region_writeback(MemoryRegion *mr, hwaddr addr, hwaddr size)
 {
     /*
      * Might be extended case needed to cover
      * different types of memory regions
      */
-    if (mr->ram_block && mr->dirty_log_mask) {
+    if (mr->dirty_log_mask) {
-        qemu_ram_writeback(mr->ram_block, addr, size);
+        memory_region_msync(mr, addr, size);
     }
 }
 

softmmu/vl.c

@@ -1993,7 +1993,7 @@ char *qemu_find_file(int type, const char *name)
     return NULL;
 }
 
-static void qemu_add_data_dir(const char *path)
+void qemu_add_data_dir(const char *path)
 {
     int i;
 

target/arm/helper.c

@@ -6813,7 +6813,7 @@ static void dccvap_writefn(CPUARMState *env, const ARMCPRegInfo *opaque,
         mr = memory_region_from_host(haddr, &offset);
 
         if (mr) {
-            memory_region_do_writeback(mr, offset, dline_size);
+            memory_region_writeback(mr, offset, dline_size);
         }
     }
 }

tests/qtest/fuzz/fork_fuzz.ld

@@ -28,6 +28,11 @@ SECTIONS
 
       /* Internal Libfuzzer TracePC object which contains the ValueProfileMap */
       FuzzerTracePC*(.bss*);
+      /*
+       * In case the above line fails, explicitly specify the (mangled) name of
+       * the object we care about
+       */
+       *(.bss._ZN6fuzzer3TPCE);
   }
   .data.fuzz_end : ALIGN(4K)
   {

tests/qtest/fuzz/fuzz.c

@@ -137,6 +137,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
 {
 
     char *target_name;
+    char *dir;
 
     /* Initialize qgraph and modules */
     qos_graph_init();
@@ -147,6 +148,20 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
     target_name = strstr(**argv, "-target-");
     if (target_name) {        /* The binary name specifies the target */
         target_name += strlen("-target-");
+        /*
+         * With oss-fuzz, the executable is kept in the root of a directory (we
+         * cannot assume the path). All data (including bios binaries) must be
+         * in the same dir, or a subdir. Thus, we cannot place the pc-bios so
+         * that it would be in exec_dir/../pc-bios.
+         * As a workaround, oss-fuzz allows us to use argv[0] to get the
+         * location of the executable. Using this we add exec_dir/pc-bios to
+         * the datadirs.
+         */
+        dir = g_build_filename(g_path_get_dirname(**argv), "pc-bios", NULL);
+        if (g_file_test(dir, G_FILE_TEST_IS_DIR)) {
+            qemu_add_data_dir(dir);
+        }
+        g_free(dir);
     } else if (*argc > 1) {  /* The target is specified as an argument */
         target_name = (*argv)[1];
         if (!strstr(target_name, "--fuzz-target=")) {

tests/qtest/fuzz/i440fx_fuzz.c

@@ -151,12 +151,13 @@ static void i440fx_fuzz_qos_fork(QTestState *s,
         i440fx_fuzz_qos(s, Data, Size);
         _Exit(0);
     } else {
+        flush_events(s);
         wait(NULL);
     }
 }
 
 static const char *i440fx_qtest_argv = TARGET_NAME " -machine accel=qtest"
-                                       "-m 0 -display none";
+                                       " -m 0 -display none";
 static const char *i440fx_argv(FuzzTarget *t)
 {
     return i440fx_qtest_argv;

tests/qtest/fuzz/virtio_net_fuzz.c

@@ -122,6 +122,7 @@ static void virtio_net_fork_fuzz(QTestState *s,
         flush_events(s);
         _Exit(0);
     } else {
+        flush_events(s);
         wait(NULL);
     }
 }
@@ -134,6 +135,7 @@ static void virtio_net_fork_fuzz_check_used(QTestState *s,
         flush_events(s);
         _Exit(0);
     } else {
+        flush_events(s);
         wait(NULL);
     }
 }

tests/qtest/fuzz/virtio_scsi_fuzz.c

@@ -145,6 +145,7 @@ static void virtio_scsi_fork_fuzz(QTestState *s,
         flush_events(s);
         _Exit(0);
     } else {
+        flush_events(s);
         wait(NULL);
     }
 }
@@ -164,6 +165,7 @@ static void virtio_scsi_with_flag_fuzz(QTestState *s,
         }
         _Exit(0);
     } else {
+        flush_events(s);
         wait(NULL);
     }
 }