From f2545b2d4ce13e068897ef60ae64dffe215f4152 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 24 May 2017 10:15:35 +0200 Subject: 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 Acked-by: Ingo Molnar Acked-by: "David S. Miller" Cc: Paul E. McKenney Cc: Chris Metcalf Cc: Peter Zijlstra Cc: Sebastian Siewior Cc: Steven Rostedt Cc: Jason Baron Cc: Ralf Baechle Link: http://lkml.kernel.org/r/20170524081549.025830817@linutronix.de --- arch/mips/kernel/jump_label.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/mips') diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c index 3e586daa3a32..32e3168316cd 100644 --- a/arch/mips/kernel/jump_label.c +++ b/arch/mips/kernel/jump_label.c @@ -58,7 +58,6 @@ void arch_jump_label_transform(struct jump_entry *e, insn.word = 0; /* nop */ } - get_online_cpus(); mutex_lock(&text_mutex); if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) { insn_p->halfword[0] = insn.word >> 16; @@ -70,7 +69,6 @@ void arch_jump_label_transform(struct jump_entry *e, (unsigned long)insn_p + sizeof(*insn_p)); mutex_unlock(&text_mutex); - put_online_cpus(); } #endif /* HAVE_JUMP_LABEL */ -- cgit