Commit e235f419 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'core-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull RT signal fix from Thomas Gleixner:
 "Revert the RT related signal changes. They need to be reworked and
  generalized"

* tag 'core-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"
parents 63d12cc3 7dd5ad2d

arch/x86/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -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

include/linux/sched.h

+0 −3
Original line number Diff line number Diff line
@@ -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;

kernel/Kconfig.preempt

+1 −11
Original line number Diff line number Diff line
@@ -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

kernel/entry/common.c

+0 −14
Original line number Diff line number Diff line
@@ -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(&current->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);

kernel/signal.c

+0 −40
Original line number Diff line number Diff line
@@ -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;