linux-kernel - [tip:smp/hotplug] s390: Prevent hotplug rwsem recursion

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Date:   Fri, 26 May 2017 01:46:46 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     heiko.carstens@...ibm.com, mingo@...nel.org,
        paulmck@...ux.vnet.ibm.com, bigeasy@...utronix.de,
        rostedt@...dmis.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de,
        schwidefsky@...ibm.com
Subject: [tip:smp/hotplug] s390: Prevent hotplug rwsem recursion

Commit-ID:  5d5dbc4ef27e72104dea6102e4d1a1bf5a8ed971
Gitweb:     http://git.kernel.org/tip/5d5dbc4ef27e72104dea6102e4d1a1bf5a8ed971
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Wed, 24 May 2017 10:15:39 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 26 May 2017 10:10:46 +0200

s390: Prevent hotplug rwsem recursion

The text patching functions which are invoked from jump_label and kprobes
code are protected against cpu hotplug at the call sites.

Use stop_machine_cpuslocked() to avoid recursion on the cpu hotplug
rwsem. stop_machine_cpuslocked() contains a lockdep assertion to catch any
unprotected callers.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: linux-s390@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Sebastian Siewior <bigeasy@...utronix.de>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Link: http://lkml.kernel.org/r/20170524081549.354513406@linutronix.de

---
 arch/s390/kernel/jump_label.c | 2 +-
 arch/s390/kernel/kprobes.c    | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c
index 6aa630a..262506c 100644
--- a/arch/s390/kernel/jump_label.c
+++ b/arch/s390/kernel/jump_label.c
@@ -93,7 +93,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
 	args.entry = entry;
 	args.type = type;
 
-	stop_machine(__sm_arch_jump_label_transform, &args, NULL);
+	stop_machine_cpuslocked(__sm_arch_jump_label_transform, &args, NULL);
 }
 
 void arch_jump_label_transform_static(struct jump_entry *entry,
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 3d6a997..6842e45 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -196,7 +196,7 @@ void arch_arm_kprobe(struct kprobe *p)
 {
 	struct swap_insn_args args = {.p = p, .arm_kprobe = 1};
 
-	stop_machine(swap_instruction, &args, NULL);
+	stop_machine_cpuslocked(swap_instruction, &args, NULL);
 }
 NOKPROBE_SYMBOL(arch_arm_kprobe);
 
@@ -204,7 +204,7 @@ void arch_disarm_kprobe(struct kprobe *p)
 {
 	struct swap_insn_args args = {.p = p, .arm_kprobe = 0};
 
-	stop_machine(swap_instruction, &args, NULL);
+	stop_machine_cpuslocked(swap_instruction, &args, NULL);
 }
 NOKPROBE_SYMBOL(arch_disarm_kprobe);