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From 4ef2c464a54b0b618d933641ac0a7012e629fed9 Mon Sep 17 00:00:00 2001
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From: Maxim Levitsky <mlevitsk@redhat.com>
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Date: Wed, 11 Mar 2020 10:51:42 +0000
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Subject: [PATCH 01/20] block/nbd: Fix hang in .bdrv_close()
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RH-Author: Maxim Levitsky <mlevitsk@redhat.com>
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Message-id: <20200311105147.13208-2-mlevitsk@redhat.com>
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Patchwork-id: 94224
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O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH v2 1/6] block/nbd: Fix hang in .bdrv_close()
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Bugzilla: 1640894
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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From: Max Reitz <mreitz@redhat.com>
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When nbd_close() is called from a coroutine, the connection_co never
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gets to run, and thus nbd_teardown_connection() hangs.
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This is because aio_co_enter() only puts the connection_co into the main
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coroutine's wake-up queue, so this main coroutine needs to yield and
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wait for connection_co to terminate.
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Suggested-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Message-Id: <20200122164532.178040-2-mreitz@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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(cherry picked from commit 78c81a3f108870d325b0a39d88711366afe6f703)
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Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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block/nbd.c | 14 +++++++++++++-
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1 file changed, 13 insertions(+), 1 deletion(-)
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diff --git a/block/nbd.c b/block/nbd.c
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index 5f18f78..a73f0d9 100644
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--- a/block/nbd.c
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+++ b/block/nbd.c
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@@ -70,6 +70,7 @@ typedef struct BDRVNBDState {
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CoMutex send_mutex;
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CoQueue free_sema;
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Coroutine *connection_co;
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+ Coroutine *teardown_co;
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QemuCoSleepState *connection_co_sleep_ns_state;
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bool drained;
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bool wait_drained_end;
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@@ -203,7 +204,15 @@ static void nbd_teardown_connection(BlockDriverState *bs)
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qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
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}
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}
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- BDRV_POLL_WHILE(bs, s->connection_co);
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+ if (qemu_in_coroutine()) {
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+ s->teardown_co = qemu_coroutine_self();
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+ /* connection_co resumes us when it terminates */
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+ qemu_coroutine_yield();
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+ s->teardown_co = NULL;
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+ } else {
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+ BDRV_POLL_WHILE(bs, s->connection_co);
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+ }
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+ assert(!s->connection_co);
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}
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static bool nbd_client_connecting(BDRVNBDState *s)
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@@ -395,6 +404,9 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
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s->ioc = NULL;
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}
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+ if (s->teardown_co) {
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+ aio_co_wake(s->teardown_co);
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+ }
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aio_wait_kick();
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}
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--
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1.8.3.1
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