diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/signal.h | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/include/linux/signal.h b/include/linux/signal.h index 14749056dd6..3fa0fab4a04 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -243,6 +243,131 @@ extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, extern struct kmem_cache *sighand_cachep; +/* + * In POSIX a signal is sent either to a specific thread (Linux task) + * or to the process as a whole (Linux thread group). How the signal + * is sent determines whether it's to one thread or the whole group, + * which determines which signal mask(s) are involved in blocking it + * from being delivered until later. When the signal is delivered, + * either it's caught or ignored by a user handler or it has a default + * effect that applies to the whole thread group (POSIX process). + * + * The possible effects an unblocked signal set to SIG_DFL can have are: + * ignore - Nothing Happens + * terminate - kill the process, i.e. all threads in the group, + * similar to exit_group. The group leader (only) reports + * WIFSIGNALED status to its parent. + * coredump - write a core dump file describing all threads using + * the same mm and then kill all those threads + * stop - stop all the threads in the group, i.e. TASK_STOPPED state + * + * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored. + * Other signals when not blocked and set to SIG_DFL behaves as follows. + * The job control signals also have other special effects. + * + * +--------------------+------------------+ + * | POSIX signal | default action | + * +--------------------+------------------+ + * | SIGHUP | terminate | + * | SIGINT | terminate | + * | SIGQUIT | coredump | + * | SIGILL | coredump | + * | SIGTRAP | coredump | + * | SIGABRT/SIGIOT | coredump | + * | SIGBUS | coredump | + * | SIGFPE | coredump | + * | SIGKILL | terminate(+) | + * | SIGUSR1 | terminate | + * | SIGSEGV | coredump | + * | SIGUSR2 | terminate | + * | SIGPIPE | terminate | + * | SIGALRM | terminate | + * | SIGTERM | terminate | + * | SIGCHLD | ignore | + * | SIGCONT | ignore(*) | + * | SIGSTOP | stop(*)(+) | + * | SIGTSTP | stop(*) | + * | SIGTTIN | stop(*) | + * | SIGTTOU | stop(*) | + * | SIGURG | ignore | + * | SIGXCPU | coredump | + * | SIGXFSZ | coredump | + * | SIGVTALRM | terminate | + * | SIGPROF | terminate | + * | SIGPOLL/SIGIO | terminate | + * | SIGSYS/SIGUNUSED | coredump | + * | SIGSTKFLT | terminate | + * | SIGWINCH | ignore | + * | SIGPWR | terminate | + * | SIGRTMIN-SIGRTMAX | terminate | + * +--------------------+------------------+ + * | non-POSIX signal | default action | + * +--------------------+------------------+ + * | SIGEMT | coredump | + * +--------------------+------------------+ + * + * (+) For SIGKILL and SIGSTOP the action is "always", not just "default". + * (*) Special job control effects: + * When SIGCONT is sent, it resumes the process (all threads in the group) + * from TASK_STOPPED state and also clears any pending/queued stop signals + * (any of those marked with "stop(*)"). This happens regardless of blocking, + * catching, or ignoring SIGCONT. When any stop signal is sent, it clears + * any pending/queued SIGCONT signals; this happens regardless of blocking, + * catching, or ignored the stop signal, though (except for SIGSTOP) the + * default action of stopping the process may happen later or never. + */ + +#ifdef SIGEMT +#define SIGEMT_MASK rt_sigmask(SIGEMT) +#else +#define SIGEMT_MASK 0 +#endif + +#if SIGRTMIN > BITS_PER_LONG +#define rt_sigmask(sig) (1ULL << ((sig)-1)) +#else +#define rt_sigmask(sig) sigmask(sig) +#endif +#define siginmask(sig, mask) (rt_sigmask(sig) & (mask)) + +#define SIG_KERNEL_ONLY_MASK (\ + rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP)) + +#define SIG_KERNEL_STOP_MASK (\ + rt_sigmask(SIGSTOP) | rt_sigmask(SIGTSTP) | \ + rt_sigmask(SIGTTIN) | rt_sigmask(SIGTTOU) ) + +#define SIG_KERNEL_COREDUMP_MASK (\ + rt_sigmask(SIGQUIT) | rt_sigmask(SIGILL) | \ + rt_sigmask(SIGTRAP) | rt_sigmask(SIGABRT) | \ + rt_sigmask(SIGFPE) | rt_sigmask(SIGSEGV) | \ + rt_sigmask(SIGBUS) | rt_sigmask(SIGSYS) | \ + rt_sigmask(SIGXCPU) | rt_sigmask(SIGXFSZ) | \ + SIGEMT_MASK ) + +#define SIG_KERNEL_IGNORE_MASK (\ + rt_sigmask(SIGCONT) | rt_sigmask(SIGCHLD) | \ + rt_sigmask(SIGWINCH) | rt_sigmask(SIGURG) ) + +#define sig_kernel_only(sig) \ + (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_ONLY_MASK)) +#define sig_kernel_coredump(sig) \ + (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_COREDUMP_MASK)) +#define sig_kernel_ignore(sig) \ + (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_IGNORE_MASK)) +#define sig_kernel_stop(sig) \ + (((sig) < SIGRTMIN) && siginmask(sig, SIG_KERNEL_STOP_MASK)) + +#define sig_needs_tasklist(sig) ((sig) == SIGCONT) + +#define sig_user_defined(t, signr) \ + (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \ + ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN)) + +#define sig_fatal(t, signr) \ + (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \ + (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL) + #endif /* __KERNEL__ */ #endif /* _LINUX_SIGNAL_H */ |