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linux/include/linux/signal.h
Oleg Nesterov d12619b5ff fix group stop with exit race 
do_signal_stop() counts all sub-thread and sets ->group_stop_count
accordingly.  Every thread should decrement ->group_stop_count and stop,
the last one should notify the parent.

However a sub-thread can exit before it notices the signal_pending(), or it
may be somewhere in do_exit() already.  In that case the group stop never
finishes properly.

Note: this is a minimal fix, we can add some optimizations later.  Say we
can return quickly if thread_group_empty().  Also, we can move some signal
related code from exit_notify() to exit_signals().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:27 -08:00

380 lines
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#ifndef _LINUX_SIGNAL_H
#define _LINUX_SIGNAL_H
#include <asm/signal.h>
#include <asm/siginfo.h>
#ifdef __KERNEL__
#include <linux/list.h>
/*
* Real Time signals may be queued.
*/
struct sigqueue {
struct list_head list;
int flags;
siginfo_t info;
struct user_struct *user;
};
/* flags values. */
#define SIGQUEUE_PREALLOC 1
struct sigpending {
struct list_head list;
sigset_t signal;
};
/*
* Define some primitives to manipulate sigset_t.
*/
#ifndef __HAVE_ARCH_SIG_BITOPS
#include <linux/bitops.h>
/* We don't use <linux/bitops.h> for these because there is no need to
be atomic. */
static inline void sigaddset(sigset_t *set, int _sig)
{
unsigned long sig = _sig - 1;
if (_NSIG_WORDS == 1)
set->sig[0] |= 1UL << sig;
else
set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
}
static inline void sigdelset(sigset_t *set, int _sig)
{
unsigned long sig = _sig - 1;
if (_NSIG_WORDS == 1)
set->sig[0] &= ~(1UL << sig);
else
set->sig[sig / _NSIG_BPW] &= ~(1UL << (sig % _NSIG_BPW));
}
static inline int sigismember(sigset_t *set, int _sig)
{
unsigned long sig = _sig - 1;
if (_NSIG_WORDS == 1)
return 1 & (set->sig[0] >> sig);
else
return 1 & (set->sig[sig / _NSIG_BPW] >> (sig % _NSIG_BPW));
}
static inline int sigfindinword(unsigned long word)
{
return ffz(~word);
}
#endif /* __HAVE_ARCH_SIG_BITOPS */
static inline int sigisemptyset(sigset_t *set)
{
extern void _NSIG_WORDS_is_unsupported_size(void);
switch (_NSIG_WORDS) {
case 4:
return (set->sig[3] | set->sig[2] |
set->sig[1] | set->sig[0]) == 0;
case 2:
return (set->sig[1] | set->sig[0]) == 0;
case 1:
return set->sig[0] == 0;
default:
_NSIG_WORDS_is_unsupported_size();
return 0;
}
}
#define sigmask(sig) (1UL << ((sig) - 1))
#ifndef __HAVE_ARCH_SIG_SETOPS
#include <linux/string.h>
#define _SIG_SET_BINOP(name, op) \
static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
{ \
extern void _NSIG_WORDS_is_unsupported_size(void); \
unsigned long a0, a1, a2, a3, b0, b1, b2, b3; \
\
switch (_NSIG_WORDS) { \
case 4: \
a3 = a->sig[3]; a2 = a->sig[2]; \
b3 = b->sig[3]; b2 = b->sig[2]; \
r->sig[3] = op(a3, b3); \
r->sig[2] = op(a2, b2); \
case 2: \
a1 = a->sig[1]; b1 = b->sig[1]; \
r->sig[1] = op(a1, b1); \
case 1: \
a0 = a->sig[0]; b0 = b->sig[0]; \
r->sig[0] = op(a0, b0); \
break; \
default: \
_NSIG_WORDS_is_unsupported_size(); \
} \
}
#define _sig_or(x,y) ((x) | (y))
_SIG_SET_BINOP(sigorsets, _sig_or)
#define _sig_and(x,y) ((x) & (y))
_SIG_SET_BINOP(sigandsets, _sig_and)
#define _sig_nand(x,y) ((x) & ~(y))
_SIG_SET_BINOP(signandsets, _sig_nand)
#undef _SIG_SET_BINOP
#undef _sig_or
#undef _sig_and
#undef _sig_nand
#define _SIG_SET_OP(name, op) \
static inline void name(sigset_t *set) \
{ \
extern void _NSIG_WORDS_is_unsupported_size(void); \
\
switch (_NSIG_WORDS) { \
case 4: set->sig[3] = op(set->sig[3]); \
set->sig[2] = op(set->sig[2]); \
case 2: set->sig[1] = op(set->sig[1]); \
case 1: set->sig[0] = op(set->sig[0]); \
break; \
default: \
_NSIG_WORDS_is_unsupported_size(); \
} \
}
#define _sig_not(x) (~(x))
_SIG_SET_OP(signotset, _sig_not)
#undef _SIG_SET_OP
#undef _sig_not
static inline void sigemptyset(sigset_t *set)
{
switch (_NSIG_WORDS) {
default:
memset(set, 0, sizeof(sigset_t));
break;
case 2: set->sig[1] = 0;
case 1: set->sig[0] = 0;
break;
}
}
static inline void sigfillset(sigset_t *set)
{
switch (_NSIG_WORDS) {
default:
memset(set, -1, sizeof(sigset_t));
break;
case 2: set->sig[1] = -1;
case 1: set->sig[0] = -1;
break;
}
}
/* Some extensions for manipulating the low 32 signals in particular. */
static inline void sigaddsetmask(sigset_t *set, unsigned long mask)
{
set->sig[0] |= mask;
}
static inline void sigdelsetmask(sigset_t *set, unsigned long mask)
{
set->sig[0] &= ~mask;
}
static inline int sigtestsetmask(sigset_t *set, unsigned long mask)
{
return (set->sig[0] & mask) != 0;
}
static inline void siginitset(sigset_t *set, unsigned long mask)
{
set->sig[0] = mask;
switch (_NSIG_WORDS) {
default:
memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
break;
case 2: set->sig[1] = 0;
case 1: ;
}
}
static inline void siginitsetinv(sigset_t *set, unsigned long mask)
{
set->sig[0] = ~mask;
switch (_NSIG_WORDS) {
default:
memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
break;
case 2: set->sig[1] = -1;
case 1: ;
}
}
#endif /* __HAVE_ARCH_SIG_SETOPS */
static inline void init_sigpending(struct sigpending *sig)
{
sigemptyset(&sig->signal);
INIT_LIST_HEAD(&sig->list);
}
extern void flush_sigqueue(struct sigpending *queue);
/* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
static inline int valid_signal(unsigned long sig)
{
return sig <= _NSIG ? 1 : 0;
}
extern int next_signal(struct sigpending *pending, sigset_t *mask);
extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p);
extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *);
extern long do_sigpending(void __user *, unsigned long);
extern int sigprocmask(int, sigset_t *, sigset_t *);
extern int show_unhandled_signals;
struct pt_regs;
extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie);
extern void exit_signals(struct task_struct *tsk);
extern struct kmem_cache *sighand_cachep;
int unhandled_signal(struct task_struct *tsk, int sig);
/*
* 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)
void signals_init(void);
#endif /* __KERNEL__ */
#endif /* _LINUX_SIGNAL_H */
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