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Message-ID: <164897466883.360450.8070511660014503126.tglx@xen13>
Date: Sun, 3 Apr 2022 10:44:12 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] core/urgent for v5.18-rc1
Linus,
please pull the latest core/urgent branch from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-2022-04-03
up to: 7dd5ad2d3e82: Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"
Revert the RT related signal changes. They need to be reworked and
generalized.
Thanks,
tglx
------------------>
Thomas Gleixner (1):
Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"
arch/x86/Kconfig | 1 -
include/linux/sched.h | 3 ---
kernel/Kconfig.preempt | 12 +-----------
kernel/entry/common.c | 14 --------------
kernel/signal.c | 40 ----------------------------------------
5 files changed, 1 insertion(+), 69 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;
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