Bug 18559
| Summary: | pthread_self and signal handler (SIGPIPE) | ||
|---|---|---|---|
| Product: | Base System | Reporter: | hwc <hwc> |
| Component: | misc | Assignee: | Jason Evans <jasone> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | ||
| Priority: | Normal | ||
| Version: | Unspecified | ||
| Hardware: | Any | ||
| OS: | Any | ||
Responsible Changed From-To: freebsd-bugs->jasone Over to maintainer. State Changed From-To: open->analyzed The problem seems to be that the main thread doesn't have SIGPIPE masked. In a threaded program, to ensure signals are delivered to the desired thread, you should set the signal mask accordingly. POSIX states that threads are selected for signal delivery in the following order: o Threads in sigwait with the signal in the wait mask (signal handler not installed) o Threads in sigsuspend with the signal being unblocked in the threads mask In lieu of finding a thread for one of the above, it is unspecified which thread should be selected for signal delivery. Our threads library chooses the first thread it finds with the signal unmasked. A properly written program should explicitly set the signal mask for threads that want to handle signals. Please try doing that and report back if things are not working as expected. State Changed From-To: analyzed->closed No additional feedback after analysis (5 1/2 months ago). |
I don't knwow is this a bug.... In the thread before use send(...) I'v use signal(SIGPIPE,sig_handler); In sig_handler, fprintf(g_log,"%d\t",pthread_self()) but I found, in sig_handler, the thread_self return main's thread_id, not the thread that use "send" ... I'v use this code in linux, in sig_handler, the thread_self return "send" thread id, as I'm assumed.. Is freebsd normal ? I'v traced /usr/src/lib/libc_r/uthread_sig.c -rw-r--r-- 1 root wheel 20777 3/22 09:19 uthread_sig.c when SIGPIPE occurs, in _thread_sig_handler(int sig, int code, ucontext_t * scp) the _thread_run (global variable, pthread_self?) is the the "send" thread, but the _thread_sig_handle(sig, scp); return the main thread I'v modified some code in _thread_sig_handle, /usr/src/lib/libc_r/uthread_sig.c, line 323 if ((_thread_sigact[sig - 1].sa_handler == SIG_IGN) || (_thread_sigact[sig - 1].sa_handler == SIG_DFL)) handler_installed = 0; else handler_installed = 1; /**** my code added begin***/ if (sig==SIGPIPE && handler_installed==1 && !sigismember(&_thread_run->sigmask, sig)) signaled_thread = _thread_run; else /**** my code end***/ for (pthread = TAILQ_FIRST(&_waitingq); pthread != NULL; pthread = pthread_next) { /* * Grab the next thread before possibly destroying * the link entry. */ pthread_next = TAILQ_NEXT(pthread, pqe); if (sig==SIGPIPE && handler_installed==1) { if (!sigismember(&_thread_run->sigmask, sig)) { signaled_thread = _thread_run; Seems fine...... I don't know will it produce side effect?