Is there some reason that syslog() sleeps in __kernel_vsyscall() when invoked from a signal handler? Is it that I am not allowed to call any system calls from inside a signal handler?
I use syslog() from a daemon client/server sys. app. that (tries) to log whenever a child exits. I've registered a sigChld handler via sigaction(using SA_SIGINFO semantics), and everything works fine and is fully functional, including calls to syslog() in the normal program flow. However, if I try to use syslog() from inside the signal handler itself, it never returns. Tracing the program with gdb, I get: Attaching to program: lfsad, process 8845 `system-supplied DSO at 0xffffe000' has disappeared; keeping its symbols. [Thread debugging using libthread_db enabled] [New Thread -1211890000 (LWP 8845)] Loaded symbols for /usr/lib/libxml2.so.2 Loaded symbols for /lib/libz.so.1 Loaded symbols for /lib/libm.so.6 Loaded symbols for /lib/librt.so.1 Loaded symbols for /lib/libc.so.6 Loaded symbols for /lib/libdl.so.2 Loaded symbols for /lib/ld-linux.so.2 Loaded symbols for /lib/libpthread.so.0 Reading symbols from /lib/libnss_files.so.2...done. Loaded symbols for /lib/libnss_files.so.2 0xffffe410 in __kernel_vsyscall () (gdb) bt #0 0xffffe410 in __kernel_vsyscall () #1 0xb7d2457e in __lll_mutex_lock_wait () from /lib/libc.so.6 #2 0xb7d14d6d in _L_mutex_lock_621 () from /lib/libc.so.6 #3 0x08511b18 in ?? () #4 0xbf86b64d in ?? () #5 0xbf86b628 in ?? () #6 0xbf86b578 in ?? () #7 0xb7d76320 in ?? () from /lib/libc.so.6 #8 0xfbad8001 in ?? () #9 0x00000014 in ?? () #10 0x00000000 in ?? () If I check its status in /proc/8845/status, I see that its sleeping. If I remove the call to syslog() in the signal handler, everything is fine, no sleeping, and the rest of the syslog() work fine. Am I doing something wrong? Thanks, John - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
