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Date: Thu, 31 Mar 2022 08:46:05 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Oleg Nesterov <oleg@...hat.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: core/urgent] Revert "signal, x86: Delay calling signals in
atomic on RT enabled kernels"
The following commit has been merged into the core/urgent branch of tip:
Commit-ID: 7dd5ad2d3e82fb55229e3fe18e09160878e77e20
Gitweb: https://git.kernel.org/tip/7dd5ad2d3e82fb55229e3fe18e09160878e77e20
Author: Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Thu, 31 Mar 2022 10:36:55 +02:00
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Thu, 31 Mar 2022 10:36:55 +02:00
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 <tglx@...utronix.de>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
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 7340d9f..442a426 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 4a6fdd2..d5e3c00 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 8c6de5a..c2f1fd9 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 ef8d94a..e57a224 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 368a34c..30cd1ca 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1308,43 +1308,6 @@ enum sig_handler {
};
/*
- * 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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