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authorThomas Gleixner <tglx@linutronix.de>2017-05-24 10:15:35 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-05-26 10:10:45 +0200
commitf2545b2d4ce13e068897ef60ae64dffe215f4152 (patch)
tree8f8808b01165daf8e5450f0d5a7fe25f322fb5a6 /arch/sparc/kernel/jump_label.c
parentperf/tracing/cpuhotplug: Fix locking order (diff)
downloadlinux-f2545b2d4ce13e068897ef60ae64dffe215f4152.tar.xz
linux-f2545b2d4ce13e068897ef60ae64dffe215f4152.zip
jump_label: Reorder hotplug lock and jump_label_lock
The conversion of the hotplug locking to a percpu rwsem unearthed lock ordering issues all over the place. The jump_label code has two issues: 1) Nested get_online_cpus() invocations 2) Ordering problems vs. the cpus rwsem and the jump_label_mutex To cure these, the following lock order has been established; cpus_rwsem -> jump_label_lock -> text_mutex Even if not all architectures need protection against CPU hotplug, taking cpus_rwsem before jump_label_lock is now mandatory in code pathes which actually modify code and therefor need text_mutex protection. Move the get_online_cpus() invocations into the core jump label code and establish the proper lock order where required. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: "David S. Miller" <davem@davemloft.net> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Ralf Baechle <ralf@linux-mips.org> Link: http://lkml.kernel.org/r/20170524081549.025830817@linutronix.de
Diffstat (limited to 'arch/sparc/kernel/jump_label.c')
-rw-r--r--arch/sparc/kernel/jump_label.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/sparc/kernel/jump_label.c b/arch/sparc/kernel/jump_label.c
index 07933b9e9ce0..93adde1ac166 100644
--- a/arch/sparc/kernel/jump_label.c
+++ b/arch/sparc/kernel/jump_label.c
@@ -41,12 +41,10 @@ void arch_jump_label_transform(struct jump_entry *entry,
val = 0x01000000;
}
- get_online_cpus();
mutex_lock(&text_mutex);
*insn = val;
flushi(insn);
mutex_unlock(&text_mutex);
- put_online_cpus();
}
#endif