[libvirt] [PATCH 2/2] qemu_conf: add set_debug_threads_name configuration key

[Marc-André Lureau]

When debug-threads is enabled, individual threads are given a separate
name (on Linux)

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=1140121

Signed-off-by: Marc-André Lureau <marcandre.lureau at redhat.com>
---
 src/qemu/libvirtd_qemu.aug         |  1 +
 src/qemu/qemu.conf                 |  6 ++++++
 src/qemu/qemu_command.c            | 14 ++++++++++----
 src/qemu/qemu_conf.c               |  1 +
 src/qemu/qemu_conf.h               |  1 +
 src/qemu/test_libvirtd_qemu.aug.in |  1 +
 6 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
index b6f6dc4..8a5e656 100644
--- a/src/qemu/libvirtd_qemu.aug
+++ b/src/qemu/libvirtd_qemu.aug
@@ -69,6 +69,7 @@ module Libvirtd_qemu =
                  | bool_entry "clear_emulator_capabilities"
                  | str_entry "bridge_helper"
                  | bool_entry "set_process_name"
+                 | bool_entry "set_debug_threads_name"
                  | int_entry "max_processes"
                  | int_entry "max_files"
                  | str_entry "stdio_handler"
diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
index 4fa5e8a..12800e9 100644
--- a/src/qemu/qemu.conf
+++ b/src/qemu/qemu.conf
@@ -380,6 +380,12 @@
 #
 #set_process_name = 1
 
+# If enabled, QEMU will name the individual QEMU threads to be
+# helpful, e.g. 'CPU/KVM 0' or 'migration'. these show up in top once
+# the H key is pressed, and also show up in a core dump, making it
+# easy to figure out which thread is which.
+#
+#set_debug_threads_name = 0
 
 # If max_processes is set to a positive integer, libvirt will use
 # it to set the maximum number of processes that can be run by qemu
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 000c29d..8c95181 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -7081,6 +7081,7 @@ qemuBuildCommandLine(virConnectPtr conn,
     virBuffer boot_buf = VIR_BUFFER_INITIALIZER;
     char *boot_order_str = NULL, *boot_opts_str = NULL;
     virBuffer fdc_opts = VIR_BUFFER_INITIALIZER;
+    virBuffer name_opts = VIR_BUFFER_INITIALIZER;
     char *fdc_opts_str = NULL;
     int bootCD = 0, bootFloppy = 0, bootDisk = 0, bootHostdevNet = 0;
 
@@ -7106,13 +7107,18 @@ qemuBuildCommandLine(virConnectPtr conn,
     virCommandAddEnvPassCommon(cmd);
 
     virCommandAddArg(cmd, "-name");
+    virBufferAsprintf(&name_opts, "%s", def->name);
     if (cfg->setProcessName &&
         virQEMUCapsGet(qemuCaps, QEMU_CAPS_NAME_PROCESS)) {
-        virCommandAddArgFormat(cmd, "%s,process=qemu:%s",
-                               def->name, def->name);
-    } else {
-        virCommandAddArg(cmd, def->name);
+        virBufferAsprintf(&name_opts, ",process=qemu:%s", def->name);
+    }
+    if (cfg->setDebugThreadsName &&
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_NAME_DEBUG_THREADS)) {
+        virBufferAddLit(&name_opts, ",debug-threads=on");
     }
+    if (virBufferCheckError(&name_opts) < 0)
+        goto error;
+    virCommandAddArg(cmd, virBufferContentAndReset(&name_opts));
 
     if (!standalone)
         virCommandAddArg(cmd, "-S"); /* freeze CPU */
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 77ef4fe..c827d71 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -794,6 +794,7 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
     GET_VALUE_BOOL("clear_emulator_capabilities", cfg->clearEmulatorCapabilities);
     GET_VALUE_BOOL("allow_disk_format_probing", cfg->allowDiskFormatProbing);
     GET_VALUE_BOOL("set_process_name", cfg->setProcessName);
+    GET_VALUE_BOOL("set_debug_threads_name", cfg->setDebugThreadsName);
     GET_VALUE_ULONG("max_processes", cfg->maxProcesses);
     GET_VALUE_ULONG("max_files", cfg->maxFiles);
 
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index a714b84..0869bfd 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -143,6 +143,7 @@ struct _virQEMUDriverConfig {
     bool clearEmulatorCapabilities;
     bool allowDiskFormatProbing;
     bool setProcessName;
+    bool setDebugThreadsName;
 
     int maxProcesses;
     int maxFiles;
diff --git a/src/qemu/test_libvirtd_qemu.aug.in b/src/qemu/test_libvirtd_qemu.aug.in
index 8bec743..bf11ef9 100644
--- a/src/qemu/test_libvirtd_qemu.aug.in
+++ b/src/qemu/test_libvirtd_qemu.aug.in
@@ -59,6 +59,7 @@ module Test_libvirtd_qemu =
 { "bridge_helper" = "/usr/libexec/qemu-bridge-helper" }
 { "clear_emulator_capabilities" = "1" }
 { "set_process_name" = "1" }
+{ "set_debug_threads_name" = "0" }
 { "max_processes" = "0" }
 { "max_files" = "0" }
 { "mac_filter" = "1" }
-- 
2.5.0