From 7dd5ad2d3e82fb55229e3fe18e09160878e77e20 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 31 Mar 2022 10:36:55 +0200 Subject: [PATCH] Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels" Revert commit bf9ad37dc8a. It needs to be better encapsulated and generalized. Signed-off-by: Thomas Gleixner Cc: "Eric W. Biederman" Cc: Oleg Nesterov Cc: Sebastian Andrzej Siewior --- arch/x86/Kconfig | 1 - include/linux/sched.h | 3 --- kernel/Kconfig.preempt | 10 ---------- kernel/entry/common.c | 14 -------------- kernel/signal.c | 40 ---------------------------------------- 5 files changed, 68 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7340d9f01b62..442a426e8a68 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -122,7 +122,6 @@ config X86 select ARCH_WANT_GENERAL_HUGETLB select ARCH_WANT_HUGE_PMD_SHARE select ARCH_WANT_LD_ORPHAN_WARN - select ARCH_WANTS_RT_DELAYED_SIGNALS select ARCH_WANTS_THP_SWAP if X86_64 select ARCH_HAS_PARANOID_L1D_FLUSH select BUILDTIME_TABLE_SORT diff --git a/include/linux/sched.h b/include/linux/sched.h index 4a6fdd2a679f..d5e3c00b74e1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1090,9 +1090,6 @@ struct task_struct { /* Restored if set_restore_sigmask() was used: */ sigset_t saved_sigmask; struct sigpending pending; -#ifdef CONFIG_RT_DELAYED_SIGNALS - struct kernel_siginfo forced_info; -#endif unsigned long sas_ss_sp; size_t sas_ss_size; unsigned int sas_ss_flags; diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index 8c6de5a9ecc4..c2f1fd95a821 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -133,14 +133,4 @@ config SCHED_CORE which is the likely usage by Linux distributions, there should be no measurable impact on performance. -config ARCH_WANTS_RT_DELAYED_SIGNALS - bool - help - This option is selected by architectures where raising signals - can happen in atomic contexts on PREEMPT_RT enabled kernels. This - option delays raising the signal until the return to user space - loop where it is also delivered. X86 requires this to deliver - signals from trap handlers which run on IST stacks. -config RT_DELAYED_SIGNALS - def_bool PREEMPT_RT && ARCH_WANTS_RT_DELAYED_SIGNALS diff --git a/kernel/entry/common.c b/kernel/entry/common.c index ef8d94a98b7e..e57a224d6b79 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -142,18 +142,6 @@ void noinstr exit_to_user_mode(void) /* Workaround to allow gradual conversion of architecture code */ void __weak arch_do_signal_or_restart(struct pt_regs *regs) { } -#ifdef CONFIG_RT_DELAYED_SIGNALS -static inline void raise_delayed_signal(void) -{ - if (unlikely(current->forced_info.si_signo)) { - force_sig_info(¤t->forced_info); - current->forced_info.si_signo = 0; - } -} -#else -static inline void raise_delayed_signal(void) { } -#endif - static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, unsigned long ti_work) { @@ -168,8 +156,6 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, if (ti_work & _TIF_NEED_RESCHED) schedule(); - raise_delayed_signal(); - if (ti_work & _TIF_UPROBE) uprobe_notify_resume(regs); diff --git a/kernel/signal.c b/kernel/signal.c index 368a34c25bbf..30cd1ca43bcd 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1307,43 +1307,6 @@ enum sig_handler { HANDLER_EXIT, /* Only visible as the process exit code */ }; -/* - * On some archictectures, PREEMPT_RT has to delay sending a signal from a - * trap since it cannot 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 CONFIG_RT_DELAYED_SIGNALS -static inline bool force_sig_delayed(struct kernel_siginfo *info, - struct task_struct *t) -{ - if (!in_atomic()) - return false; - - if (WARN_ON_ONCE(t->forced_info.si_signo)) - return true; - - if (is_si_special(info)) { - WARN_ON_ONCE(info != SEND_SIG_PRIV); - t->forced_info.si_signo = info->si_signo; - 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 true; -} -#else -static inline bool force_sig_delayed(struct kernel_siginfo *info, - struct task_struct *t) -{ - return false; -} -#endif - /* * Force a signal that the process can't ignore: if necessary * we unblock the signal and change any SIG_IGN to SIG_DFL. @@ -1364,9 +1327,6 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, struct k_sigaction *action; int sig = info->si_signo; - if (force_sig_delayed(info, t)) - return 0; - spin_lock_irqsave(&t->sighand->siglock, flags); action = &t->sighand->action[sig-1]; ignored = action->sa.sa_handler == SIG_IGN;