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From: Alexander Bulekov <alxndr@bu.edu>
To: qemu-devel@nongnu.org
Cc: Alexander Bulekov <alxndr@bu.edu>,
	pbonzini@redhat.com, bsd@redhat.com, stefanha@redhat.com,
	darren.kenny@oracle.com
Subject: [PATCH v10 14/22] main: keep rcu_atfork callback enabled for qtest
Date: Wed, 19 Feb 2020 23:11:10 -0500	[thread overview]
Message-ID: <20200220041118.23264-15-alxndr@bu.edu> (raw)
In-Reply-To: <20200220041118.23264-1-alxndr@bu.edu>

The qtest-based fuzzer makes use of forking to reset-state between
tests. Keep the callback enabled, so the call_rcu thread gets created
within the child process.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 softmmu/vl.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/softmmu/vl.c b/softmmu/vl.c
index 46a48d09df..78f6530620 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -3813,7 +3813,17 @@ void qemu_init(int argc, char **argv, char **envp)
     set_memory_options(&ram_slots, &maxram_size, machine_class);
 
     os_daemonize();
-    rcu_disable_atfork();
+
+    /*
+     * If QTest is enabled, keep the rcu_atfork enabled, since system processes
+     * may be forked testing purposes (e.g. fork-server based fuzzing) The fork
+     * should happen before a signle cpu instruction is executed, to prevent
+     * deadlocks. See commit 73c6e40, rcu: "completely disable pthread_atfork
+     * callbacks as soon as possible"
+     */
+    if (!qtest_enabled()) {
+        rcu_disable_atfork();
+    }
 
     if (pid_file && !qemu_write_pidfile(pid_file, &err)) {
         error_reportf_err(err, "cannot create PID file: ");
-- 
2.25.0



  parent reply	other threads:[~2020-02-20  4:14 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-20  4:10 [PATCH v10 00/22] Add virtual device fuzzing support Alexander Bulekov
2020-02-20  4:10 ` [PATCH v10 01/22] softmmu: move vl.c to softmmu/ Alexander Bulekov
2020-02-20 10:33   ` Darren Kenny
2020-02-21 13:56   ` Stefan Hajnoczi
2020-02-20  4:10 ` [PATCH v10 02/22] softmmu: split off vl.c:main() into main.c Alexander Bulekov
2020-02-20  4:10 ` [PATCH v10 03/22] module: check module wasn't already initialized Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 04/22] fuzz: add FUZZ_TARGET module type Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 05/22] qtest: add qtest_server_send abstraction Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 06/22] libqtest: add a layer of abstraction to send/recv Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 07/22] libqtest: make bufwrite rely on the TransportOps Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 08/22] qtest: add in-process incoming command handler Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 09/22] libqos: rename i2c_send and i2c_recv Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 10/22] libqos: split qos-test and libqos makefile vars Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 11/22] libqos: move useful qos-test funcs to qos_external Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 12/22] fuzz: add fuzzer skeleton Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 13/22] exec: keep ram block across fork when using qtest Alexander Bulekov
2020-02-20  4:11 ` Alexander Bulekov [this message]
2020-02-20  4:11 ` [PATCH v10 15/22] fuzz: support for fork-based fuzzing Alexander Bulekov
2020-02-20 10:34   ` Darren Kenny
2020-02-20  4:11 ` [PATCH v10 16/22] fuzz: add support for qos-assisted fuzz targets Alexander Bulekov
2020-02-20 10:35   ` Darren Kenny
2020-02-20  4:11 ` [PATCH v10 17/22] fuzz: add target/fuzz makefile rules Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 18/22] fuzz: add configure flag --enable-fuzzing Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 19/22] fuzz: add i440fx fuzz targets Alexander Bulekov
2020-02-20  4:11 ` [PATCH v10 20/22] fuzz: add virtio-net fuzz target Alexander Bulekov
2020-02-20 10:35   ` Darren Kenny
2020-02-20  4:11 ` [PATCH v10 21/22] fuzz: add virtio-scsi " Alexander Bulekov
2020-02-20 10:38   ` Darren Kenny
2020-02-21 13:57   ` Stefan Hajnoczi
2020-02-20  4:11 ` [PATCH v10 22/22] fuzz: add documentation to docs/devel/ Alexander Bulekov
2020-02-21 15:17 ` [PATCH v10 00/22] Add virtual device fuzzing support Stefan Hajnoczi

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