An earlier commit(c0c8c1) Dan removed global log buffer feature entirely
because of duplicate log messages. An improvement is introduced. That is
dumping stack trace instead of log buffer upon libvirt crash.
Signed-off-by: Zhou Yimin <zhouyimin@xxxxxxxxxx>
Signed-off-by: Wang Rui <moon.wangrui@xxxxxxxxxx>
---
When libvirt receives fatal signal, the log output shows as following.
Caught abort signal dumping stack trace:
====== start of stack trace =====
/usr/lib64/libvirt.so.0(+0x1d4fde)[0x7f001b1b0fde]
/lib64/libpthread.so.0(+0xf800)[0x7f00182ed800]
/lib64/libc.so.6(gsignal+0x35)[0x7f0017b91b55]
/lib64/libc.so.6(abort+0x181)[0x7f0017b93131]
/lib64/libc.so.6(+0x70e0f)[0x7f0017bcfe0f]
/lib64/libc.so.6(+0x76618)[0x7f0017bd5618]
/lib64/libc.so.6(+0x76c3f)[0x7f0017bd5c3f]
/lib64/libc.so.6(+0x78fee)[0x7f0017bd7fee]
/lib64/libc.so.6(__libc_malloc+0x77)[0x7f0017bda747]
/usr/lib64/libvirt.so.0(virReallocN+0x65)[0x7f001b03c06d]
/usr/lib64/libvirt.so.0(+0x7ebbc)[0x7f001b05abbc]
/usr/lib64/libvirt.so.0(virFileReadLimFD+0x50)[0x7f001b05ad4a]
/usr/lib64/libvirt.so.0(virFileReadAll+0xa6)[0x7f001b05c7d1]
/usr/lib64/libvirt.so.0(virProcessGetStartTime+0x9a)[0x7f001b080ee9]
/usr/lib64/libvirt.so.0(virNetSocketGetUNIXIdentity+0xc1)[0x7f001b1bf709]
/usr/lib64/libvirt.so.0(virNetServerClientGetUNIXIdentity+0x68)[0x7f001b1b35b6]
/usr/sbin/libvirtd(+0x20103)[0x7f001bb8f103]
/usr/sbin/libvirtd(+0x20347)[0x7f001bb8f347]
/usr/lib64/libvirt.so.0(+0x1db9bd)[0x7f001b1b79bd]
/usr/lib64/libvirt.so.0(virNetServerProgramDispatch+0x209)[0x7f001b1b7dff]
/usr/lib64/libvirt.so.0(+0x1d5448)[0x7f001b1b1448]
/usr/lib64/libvirt.so.0(+0x1d572a)[0x7f001b1b172a]
/usr/lib64/libvirt.so.0(+0xb3964)[0x7f001b08f964]
/usr/lib64/libvirt.so.0(+0xb2dd0)[0x7f001b08edd0]
/lib64/libpthread.so.0(+0x77f6)[0x7f00182e57f6]
/lib64/libc.so.6(clone+0x6d)[0x7f0017c3a09d]
====== end of stack trace =====
src/libvirt_private.syms | 1 +
src/rpc/virnetserver.c | 43 +++++++++++++++++++++++
src/util/virlog.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++
src/util/virlog.h | 2 ++
4 files changed, 134 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index c3332c9..d781595 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1501,6 +1501,7 @@ virLogGetFilters;
virLogGetNbFilters;
virLogGetNbOutputs;
virLogGetOutputs;
+virLogEmergencyDumpAll;
virLogLock;
virLogMessage;
virLogParseDefaultPriority;
diff --git a/src/rpc/virnetserver.c b/src/rpc/virnetserver.c
index 7e3fc0a..2845098 100644
--- a/src/rpc/virnetserver.c
+++ b/src/rpc/virnetserver.c
@@ -340,6 +340,32 @@ static int virNetServerDispatchNewClient(virNetServerServicePtr svc,
return 0;
}
+static void
+virNetServerFatalSignal(int sig, siginfo_t *siginfo ATTRIBUTE_UNUSED,
+ void *context ATTRIBUTE_UNUSED)
+{
+ struct sigaction sig_action;
+ int origerrno;
+
+ origerrno = errno;
+ virLogEmergencyDumpAll(sig);
+
+ /*
+ * If the signal is fatal, avoid looping over this handler
+ * by deactivating it
+ */
+#ifdef SIGUSR2
+ if (sig != SIGUSR2) {
+#endif
+ memset(&sig_action, 0, sizeof(sig_action));
+ sig_action.sa_handler = SIG_DFL;
+ sigaction(sig, &sig_action, NULL);
+ raise(sig);
+#ifdef SIGUSR2
+ }
+#endif
+ errno = origerrno;
+}
virNetServerPtr virNetServerNew(size_t min_workers,
size_t max_workers,
@@ -401,6 +427,23 @@ virNetServerPtr virNetServerNew(size_t min_workers,
sig_action.sa_handler = SIG_IGN;
sigaction(SIGPIPE, &sig_action, NULL);
+ /*
+ * catch fatal errors to dump stack trace, also hook to USR2 for dynamic
+ * debugging purposes or testing
+ */
+ sig_action.sa_sigaction = virNetServerFatalSignal;
+ sig_action.sa_flags = SA_SIGINFO;
+ sigaction(SIGFPE, &sig_action, NULL);
+ sigaction(SIGSEGV, &sig_action, NULL);
+ sigaction(SIGILL, &sig_action, NULL);
+ sigaction(SIGABRT, &sig_action, NULL);
+#ifdef SIGBUS
+ sigaction(SIGBUS, &sig_action, NULL);
+#endif
+#ifdef SIGUSR2
+ sigaction(SIGUSR2, &sig_action, NULL);
+#endif
+
return srv;
error:
diff --git a/src/util/virlog.c b/src/util/virlog.c
index 056950e..081b194 100644
--- a/src/util/virlog.c
+++ b/src/util/virlog.c
@@ -30,6 +30,7 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
+#include <signal.h>
#include <execinfo.h>
#include <regex.h>
#if HAVE_SYSLOG_H
@@ -661,6 +662,93 @@ virLogStackTraceToFd(int fd)
}
static void
+virLogDumpAllFD(const char *msg, int len)
+{
+ size_t i;
+ bool found = false;
+
+ if (len <= 0)
+ len = strlen(msg);
+
+ for (i = 0; i < virLogNbOutputs; i++) {
+ if (virLogOutputs[i].f == virLogOutputToFd) {
+ int fd = (intptr_t) virLogOutputs[i].data;
+
+ if (fd >= 0) {
+ if (msg)
+ ignore_value(safewrite(fd, msg, len));
+ else
+ virLogStackTraceToFd(fd);
+
+ found = true;
+ }
+ }
+ }
+ if (!found) {
+ if (msg)
+ ignore_value(safewrite(STDERR_FILENO, msg, len));
+ else
+ virLogStackTraceToFd(STDERR_FILENO);
+ }
+}
+
+/**
+ * virLogEmergencyDumpAll:
+ * @signum: the signal number
+ *
+ * Emergency function called, possibly from a signal handler.
+ * It need to output the stack trace through the log output
+ * which are safe to use from a signal handler.
+ * In case none is found it is emitted to standard error.
+ */
+void
+virLogEmergencyDumpAll(int signum)
+{
+ switch (signum) {
+#ifdef SIGFPE
+ case SIGFPE:
+ virLogDumpAllFD("Caught signal Floating-point exception", -1);
+ break;
+#endif
+#ifdef SIGSEGV
+ case SIGSEGV:
+ virLogDumpAllFD("Caught Segmentation violation", -1);
+ break;
+#endif
+#ifdef SIGILL
+ case SIGILL:
+ virLogDumpAllFD("Caught illegal instruction", -1);
+ break;
+#endif
+#ifdef SIGABRT
+ case SIGABRT:
+ virLogDumpAllFD("Caught abort signal", -1);
+ break;
+#endif
+#ifdef SIGBUS
+ case SIGBUS:
+ virLogDumpAllFD("Caught bus error", -1);
+ break;
+#endif
+#ifdef SIGUSR2
+ case SIGUSR2:
+ virLogDumpAllFD("Caught User-defined signal 2", -1);
+ break;
+#endif
+ default:
+ virLogDumpAllFD("Caught unexpected signal", -1);
+ break;
+ }
+
+ virLogDumpAllFD(" dumping stack trace:\n", -1);
+ virLogDumpAllFD("\n\n ====== start of stack trace =====\n\n", -1);
+
+ virLogDumpAllFD(NULL, 1);
+
+ virLogDumpAllFD("\n\n ====== end of stack trace =====\n\n", -1);
+}
+
+static void
virLogOutputToFd(virLogSourcePtr source ATTRIBUTE_UNUSED,
virLogPriority priority ATTRIBUTE_UNUSED,
const char *filename ATTRIBUTE_UNUSED,
diff --git a/src/util/virlog.h b/src/util/virlog.h
index 5b38891..628a2b1 100644
--- a/src/util/virlog.h
+++ b/src/util/virlog.h
@@ -201,6 +201,8 @@ extern void virLogVMessage(virLogSourcePtr source,
const char *fmt,
va_list vargs) ATTRIBUTE_FMT_PRINTF(7, 0);
+extern void virLogEmergencyDumpAll(int signum);
+
bool virLogProbablyLogMessage(const char *str);
#endif
--
1.7.12.4
--
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