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[sanitizer] Fix log_path behavior with StopTheWorld. 

Summary:
Fix race on report_fd/report_fd_pid between the parent process and the
tracer task.

Reviewers: samsonov

Reviewed By: samsonov

CC: llvm-commits, kcc, dvyukov

Differential Revision: http://llvm-reviews.chandlerc.com/D2306

llvm-svn: 196385
This commit is contained in:
Sergey Matveev 2013-12-04 14:37:01 +00:00
parent 06dd15a01a
commit 7bc300c8fc
4 changed files with 32 additions and 3 deletions
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7
compiler-rt/lib/sanitizer_common/sanitizer_common.cc
View File

@ -42,6 +42,13 @@ char report_path_prefix[sizeof(report_path_prefix)];
// child thread will be different from |report_fd_pid|.
uptr report_fd_pid = 0;
// PID of the tracer task in StopTheWorld. It shares the address space with the
// main process, but has a different PID and thus requires special handling.
uptr stoptheworld_tracer_pid = 0;
// Cached pid of parent process - if the parent process dies, we want to keep
// writing to the same log file.
uptr stoptheworld_tracer_ppid = 0;
static DieCallbackType DieCallback;
void SetDieCallback(DieCallbackType callback) {
DieCallback = callback;

2
compiler-rt/lib/sanitizer_common/sanitizer_common.h
View File

@ -136,6 +136,8 @@ extern fd_t report_fd;
extern bool log_to_file;
extern char report_path_prefix[4096];
extern uptr report_fd_pid;
extern uptr stoptheworld_tracer_pid;
extern uptr stoptheworld_tracer_ppid;
uptr OpenFile(const char *filename, bool write);
// Opens the file 'file_name" and reads up to 'max_len' bytes.

11
compiler-rt/lib/sanitizer_common/sanitizer_posix.cc
View File

@ -198,10 +198,15 @@ char *FindPathToBinary(const char *name) {
}
void MaybeOpenReportFile() {
if (!log_to_file || (report_fd_pid == internal_getpid())) return;
if (!log_to_file) return;
uptr pid = internal_getpid();
// If in tracer, use the parent's file.
if (pid == stoptheworld_tracer_pid)
pid = stoptheworld_tracer_ppid;
if (report_fd_pid == pid) return;
InternalScopedBuffer<char> report_path_full(4096);
internal_snprintf(report_path_full.data(), report_path_full.size(),
"%s.%d", report_path_prefix, internal_getpid());
"%s.%d", report_path_prefix, pid);
uptr openrv = OpenFile(report_path_full.data(), true);
if (internal_iserror(openrv)) {
report_fd = kStderrFd;
@ -214,7 +219,7 @@ void MaybeOpenReportFile() {
internal_close(report_fd);
}
report_fd = openrv;
report_fd_pid = internal_getpid();
report_fd_pid = pid;
}
void RawWrite(const char *buffer) {

15
compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
View File

@ -356,6 +356,20 @@ class StopTheWorldScope {
int process_was_dumpable_;
};
// When sanitizer output is being redirected to file (i.e. by using log_path),
// the tracer should write to the parent's log instead of trying to open a new
// file. Alert the logging code to the fact that we have a tracer.
struct ScopedSetTracerPID {
explicit ScopedSetTracerPID(uptr tracer_pid) {
stoptheworld_tracer_pid = tracer_pid;
stoptheworld_tracer_ppid = internal_getpid();
}
~ScopedSetTracerPID() {
stoptheworld_tracer_pid = 0;
stoptheworld_tracer_ppid = 0;
}
};
void StopTheWorld(StopTheWorldCallback callback, void *argument) {
StopTheWorldScope in_stoptheworld;
// Prepare the arguments for TracerThread.
@ -379,6 +393,7 @@ void StopTheWorld(StopTheWorldCallback callback, void *argument) {
Report("Failed spawning a tracer thread (errno %d).\n", local_errno);
tracer_thread_argument.mutex.Unlock();
} else {
ScopedSetTracerPID scoped_set_tracer_pid(tracer_pid);
// On some systems we have to explicitly declare that we want to be traced
// by the tracer thread.
#ifdef PR_SET_PTRACER