diff options
| -rw-r--r-- | arch/x86/include/asm/signal.h | 13 | ||||
| -rw-r--r-- | arch/x86/kernel/signal.c | 9 | ||||
| -rw-r--r-- | include/linux/sched.h | 4 | ||||
| -rw-r--r-- | kernel/signal.c | 37 |
4 files changed, 61 insertions, 2 deletions
diff --git a/arch/x86/include/asm/signal.h b/arch/x86/include/asm/signal.h index 598457cbd0f8..1213ebd7bee7 100644 --- a/arch/x86/include/asm/signal.h +++ b/arch/x86/include/asm/signal.h @@ -31,6 +31,19 @@ typedef struct { unsigned long sig[_NSIG_WORDS]; } sigset_t; +/* + * Because some traps use the IST stack, we must keep + * preemption disabled while calling do_trap(), but do_trap() + * may call force_sig_info() which will grab the signal spin_locks + * for the task, which in PREEMPT_RT_FULL are mutexes. + * By defining ARCH_RT_DELAYS_SIGNAL_SEND the force_sig_info() will + * set TIF_NOTIFY_RESUME and set up the signal to be sent on exit + * of the trap. + */ +#if defined(CONFIG_PREEMPT_RT_FULL) && defined(CONFIG_X86_64) +#define ARCH_RT_DELAYS_SIGNAL_SEND +#endif + #else /* Here we must cater to libcs that poke about in kernel headers. */ diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 115eac431483..c67d83fe0d00 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -824,6 +824,15 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) mce_notify_process(); #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ +#ifdef ARCH_RT_DELAYS_SIGNAL_SEND + if (unlikely(current->forced_info.si_signo)) { + struct task_struct *t = current; + force_sig_info(t->forced_info.si_signo, + &t->forced_info, t); + t->forced_info.si_signo = 0; + } +#endif + /* deal with pending signal delivery */ if (thread_info_flags & _TIF_SIGPENDING) do_signal(regs); diff --git a/include/linux/sched.h b/include/linux/sched.h index b546194cc4d8..bd5caa1cd436 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1440,6 +1440,10 @@ struct task_struct { sigset_t blocked, real_blocked; sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */ struct sigpending pending; +#ifdef CONFIG_PREEMPT_RT_FULL + /* TODO: move me into ->restart_block ? */ + struct siginfo forced_info; +#endif unsigned long sas_ss_sp; size_t sas_ss_size; diff --git a/kernel/signal.c b/kernel/signal.c index a05a4db27173..65cb5b459765 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1312,8 +1312,8 @@ int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, * We don't want to have recursive SIGSEGV's etc, for example, * that is why we also clear SIGNAL_UNKILLABLE. */ -int -force_sig_info(int sig, struct siginfo *info, struct task_struct *t) +static int +do_force_sig_info(int sig, struct siginfo *info, struct task_struct *t) { unsigned long int flags; int ret, blocked, ignored; @@ -1338,6 +1338,39 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) return ret; } +int force_sig_info(int sig, struct siginfo *info, struct task_struct *t) +{ +/* + * On some archs, PREEMPT_RT has to delay sending a signal from a trap + * since it can not enable preemption, and the signal code's spin_locks + * turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME which will + * send the signal on exit of the trap. + */ +#ifdef ARCH_RT_DELAYS_SIGNAL_SEND + if (in_atomic()) { + if (WARN_ON_ONCE(t != current)) + return 0; + if (WARN_ON_ONCE(t->forced_info.si_signo)) + return 0; + + if (is_si_special(info)) { + WARN_ON_ONCE(info != SEND_SIG_PRIV); + t->forced_info.si_signo = sig; + t->forced_info.si_errno = 0; + t->forced_info.si_code = SI_KERNEL; + t->forced_info.si_pid = 0; + t->forced_info.si_uid = 0; + } else { + t->forced_info = *info; + } + + set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + return 0; + } +#endif + return do_force_sig_info(sig, info, t); +} + /* * Nuke all other threads in the group. */ |