From 74105e9b2d948c03786e0f86f116d5e410e8d1c6 Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Wed, 10 Oct 2018 20:21:44 +0100

Subject: [PATCH 18/49] test-bdrv-drain: Test that bdrv_drain_invoke() doesn't

 poll

RH-Author: Kevin Wolf <kwolf@redhat.com>

Message-id: <20181010202213.7372-6-kwolf@redhat.com>

Patchwork-id: 82593

O-Subject: [RHEL-8 qemu-kvm PATCH 15/44] test-bdrv-drain: Test that bdrv_drain_invoke() doesn't poll

Bugzilla: 1637976

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Thomas Huth <thuth@redhat.com>

This adds a test case that goes wrong if bdrv_drain_invoke() calls

aio_poll().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 57320ca961c2e8488e1884b4ebbcb929b6901dc6)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 tests/test-bdrv-drain.c | 102 +++++++++++++++++++++++++++++++++++++++++-------

 1 file changed, 88 insertions(+), 14 deletions(-)

diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c

index f786326..c4aa913 100644

--- a/tests/test-bdrv-drain.c

+++ b/tests/test-bdrv-drain.c

@@ -34,12 +34,16 @@ static QemuEvent done_event;

 typedef struct BDRVTestState {

     int drain_count;

     AioContext *bh_indirection_ctx;

+    bool sleep_in_drain_begin;

 } BDRVTestState;

 static void coroutine_fn bdrv_test_co_drain_begin(BlockDriverState *bs)

 {

     BDRVTestState *s = bs->opaque;

     s->drain_count++;

+    if (s->sleep_in_drain_begin) {

+        qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, 100000);

+    }

 }

 static void coroutine_fn bdrv_test_co_drain_end(BlockDriverState *bs)

@@ -80,6 +84,22 @@ static int coroutine_fn bdrv_test_co_preadv(BlockDriverState *bs,

     return 0;

 }

+static void bdrv_test_child_perm(BlockDriverState *bs, BdrvChild *c,

+                                 const BdrvChildRole *role,

+                                 BlockReopenQueue *reopen_queue,

+                                 uint64_t perm, uint64_t shared,

+                                 uint64_t *nperm, uint64_t *nshared)

+{

+    /* bdrv_format_default_perms() accepts only these two, so disguise

+     * detach_by_driver_cb_role as one of them. */

+    if (role != &child_file && role != &child_backing) {

+        role = &child_file;

+    }

+

+    bdrv_format_default_perms(bs, c, role, reopen_queue, perm, shared,

+                              nperm, nshared);

+}

+

 static BlockDriver bdrv_test = {

     .format_name            = "test",

     .instance_size          = sizeof(BDRVTestState),

@@ -90,7 +110,7 @@ static BlockDriver bdrv_test = {

     .bdrv_co_drain_begin    = bdrv_test_co_drain_begin,

     .bdrv_co_drain_end      = bdrv_test_co_drain_end,

-    .bdrv_child_perm        = bdrv_format_default_perms,

+    .bdrv_child_perm        = bdrv_test_child_perm,

 };

 static void aio_ret_cb(void *opaque, int ret)

@@ -982,13 +1002,14 @@ struct detach_by_parent_data {

     BdrvChild *child_b;

     BlockDriverState *c;

     BdrvChild *child_c;

+    bool by_parent_cb;

 };

+static struct detach_by_parent_data detach_by_parent_data;

-static void detach_by_parent_aio_cb(void *opaque, int ret)

+static void detach_indirect_bh(void *opaque)

 {

     struct detach_by_parent_data *data = opaque;

-    g_assert_cmpint(ret, ==, 0);

     bdrv_unref_child(data->parent_b, data->child_b);

     bdrv_ref(data->c);

@@ -996,6 +1017,25 @@ static void detach_by_parent_aio_cb(void *opaque, int ret)

                                       &child_file, &error_abort);

 }

+static void detach_by_parent_aio_cb(void *opaque, int ret)

+{

+    struct detach_by_parent_data *data = &detach_by_parent_data;

+

+    g_assert_cmpint(ret, ==, 0);

+    if (data->by_parent_cb) {

+        detach_indirect_bh(data);

+    }

+}

+

+static void detach_by_driver_cb_drained_begin(BdrvChild *child)

+{

+    aio_bh_schedule_oneshot(qemu_get_current_aio_context(),

+                            detach_indirect_bh, &detach_by_parent_data);

+    child_file.drained_begin(child);

+}

+

+static BdrvChildRole detach_by_driver_cb_role;

+

 /*

  * Initial graph:

  *

@@ -1003,17 +1043,25 @@ static void detach_by_parent_aio_cb(void *opaque, int ret)

  *    \ /   \

  *     A     B     C

  *

- * PA has a pending write request whose callback changes the child nodes of PB:

- * It removes B and adds C instead. The subtree of PB is drained, which will

- * indirectly drain the write request, too.

+ * by_parent_cb == true:  Test that parent callbacks don't poll

+ *

+ *     PA has a pending write request whose callback changes the child nodes of

+ *     PB: It removes B and adds C instead. The subtree of PB is drained, which

+ *     will indirectly drain the write request, too.

+ *

+ * by_parent_cb == false: Test that bdrv_drain_invoke() doesn't poll

+ *

+ *     PA's BdrvChildRole has a .drained_begin callback that schedules a BH

+ *     that does the same graph change. If bdrv_drain_invoke() calls it, the

+ *     state is messed up, but if it is only polled in the single

+ *     BDRV_POLL_WHILE() at the end of the drain, this should work fine.

  */

-static void test_detach_by_parent_cb(void)

+static void test_detach_indirect(bool by_parent_cb)

 {

     BlockBackend *blk;

     BlockDriverState *parent_a, *parent_b, *a, *b, *c;

     BdrvChild *child_a, *child_b;

     BlockAIOCB *acb;

-    struct detach_by_parent_data data;

     QEMUIOVector qiov;

     struct iovec iov = {

@@ -1022,6 +1070,12 @@ static void test_detach_by_parent_cb(void)

     };

     qemu_iovec_init_external(&qiov, &iov, 1);

+    if (!by_parent_cb) {

+        detach_by_driver_cb_role = child_file;

+        detach_by_driver_cb_role.drained_begin =

+            detach_by_driver_cb_drained_begin;

+    }

+

     /* Create all involved nodes */

     parent_a = bdrv_new_open_driver(&bdrv_test, "parent-a", BDRV_O_RDWR,

                                     &error_abort);

@@ -1037,6 +1091,13 @@ static void test_detach_by_parent_cb(void)

     blk_insert_bs(blk, parent_a, &error_abort);

     bdrv_unref(parent_a);

+    /* If we want to get bdrv_drain_invoke() to call aio_poll(), the driver

+     * callback must not return immediately. */

+    if (!by_parent_cb) {

+        BDRVTestState *s = parent_a->opaque;

+        s->sleep_in_drain_begin = true;

+    }

+

     /* Set child relationships */

     bdrv_ref(b);

     bdrv_ref(a);

@@ -1044,7 +1105,9 @@ static void test_detach_by_parent_cb(void)

     child_a = bdrv_attach_child(parent_b, a, "PB-A", &child_backing, &error_abort);

     bdrv_ref(a);

-    bdrv_attach_child(parent_a, a, "PA-A", &child_file, &error_abort);

+    bdrv_attach_child(parent_a, a, "PA-A",

+                      by_parent_cb ? &child_file : &detach_by_driver_cb_role,

+                      &error_abort);

     g_assert_cmpint(parent_a->refcnt, ==, 1);

     g_assert_cmpint(parent_b->refcnt, ==, 1);

@@ -1057,18 +1120,19 @@ static void test_detach_by_parent_cb(void)

     g_assert(QLIST_NEXT(child_b, next) == NULL);

     /* Start the evil write request */

-    data = (struct detach_by_parent_data) {

+    detach_by_parent_data = (struct detach_by_parent_data) {

         .parent_b = parent_b,

         .child_b = child_b,

         .c = c,

+        .by_parent_cb = by_parent_cb,

     };

-    acb = blk_aio_preadv(blk, 0, &qiov, 0, detach_by_parent_aio_cb, &data);

+    acb = blk_aio_preadv(blk, 0, &qiov, 0, detach_by_parent_aio_cb, NULL);

     g_assert(acb != NULL);

     /* Drain and check the expected result */

     bdrv_subtree_drained_begin(parent_b);

-    g_assert(data.child_c != NULL);

+    g_assert(detach_by_parent_data.child_c != NULL);

     g_assert_cmpint(parent_a->refcnt, ==, 1);

     g_assert_cmpint(parent_b->refcnt, ==, 1);

@@ -1076,8 +1140,8 @@ static void test_detach_by_parent_cb(void)

     g_assert_cmpint(b->refcnt, ==, 1);

     g_assert_cmpint(c->refcnt, ==, 2);

-    g_assert(QLIST_FIRST(&parent_b->children) == data.child_c);

-    g_assert(QLIST_NEXT(data.child_c, next) == child_a);

+    g_assert(QLIST_FIRST(&parent_b->children) == detach_by_parent_data.child_c);

+    g_assert(QLIST_NEXT(detach_by_parent_data.child_c, next) == child_a);

     g_assert(QLIST_NEXT(child_a, next) == NULL);

     g_assert_cmpint(parent_a->quiesce_counter, ==, 1);

@@ -1105,6 +1169,15 @@ static void test_detach_by_parent_cb(void)

     bdrv_unref(c);

 }

+static void test_detach_by_parent_cb(void)

+{

+    test_detach_indirect(true);

+}

+

+static void test_detach_by_driver_cb(void)

+{

+    test_detach_indirect(false);

+}

 int main(int argc, char **argv)

 {

@@ -1157,6 +1230,7 @@ int main(int argc, char **argv)

     g_test_add_func("/bdrv-drain/detach/drain", test_detach_by_drain);

     g_test_add_func("/bdrv-drain/detach/drain_subtree", test_detach_by_drain_subtree);

     g_test_add_func("/bdrv-drain/detach/parent_cb", test_detach_by_parent_cb);

+    g_test_add_func("/bdrv-drain/detach/driver_cb", test_detach_by_driver_cb);

     ret = g_test_run();

     qemu_event_destroy(&done_event);

-- 

1.8.3.1