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| author | Daniel P. Berrange <berrange@redhat.com> | 2016-10-04 14:35:51 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2016-10-12 09:35:54 +0200 |
| commit | 8ed5372874377af4a84a330eeaff1d9d663ca930 (patch) | |
| tree | 56df50260e123fea831136b9f3a4b9066cb34430 | |
| parent | 7f1b588f20d027730676e627713ae3bbf6baab04 (diff) | |
| download | focaccia-qemu-8ed5372874377af4a84a330eeaff1d9d663ca930.tar.gz focaccia-qemu-8ed5372874377af4a84a330eeaff1d9d663ca930.zip | |
trace: don't abort qemu if ftrace can't be initialized
If the ftrace backend is compiled into QEMU, any attempt to start QEMU while non-root will fail due to the inability to open /sys/kernel/debug/tracing/tracing_on. Add a fallback into the code so that it connects up the trace_marker_fd variable to /dev/null when getting EACCES on the 'trace_on' file. This allows QEMU to run, with ftrace turned into a no-op. [Fixed s/setting/getting/ and s/EACCESS/EACCES/ errors pointed out by Eric Blake <eblake@redhat.com>. --Stefan] Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 1475588159-30598-13-git-send-email-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
| -rw-r--r-- | trace/ftrace.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/trace/ftrace.c b/trace/ftrace.c index e953922f5b..3588bb0eb4 100644 --- a/trace/ftrace.c +++ b/trace/ftrace.c @@ -51,6 +51,12 @@ bool ftrace_init(void) snprintf(path, PATH_MAX, "%s/tracing/tracing_on", debugfs); trace_fd = open(path, O_WRONLY); if (trace_fd < 0) { + if (errno == EACCES) { + trace_marker_fd = open("/dev/null", O_WRONLY); + if (trace_marker_fd != -1) { + return true; + } + } perror("Could not open ftrace 'tracing_on' file"); return false; } else { |