From: Stephen Boyd <sboyd@codeaurora.org>
Date: Wed, 24 Jun 2015 20:14:18 +0000 (-0700)
Subject: ARM64: smp: Fix suspicious RCU usage with ipi tracepoints
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=be081d9bf3e163a9ed1ca2f0f14f08424c7f9016;p=linux-beck.git

ARM64: smp: Fix suspicious RCU usage with ipi tracepoints

John Stultz reported an RCU splat on ARM with ipi trace events
enabled. It looks like the same problem exists on ARM64.

At this point in the IPI handling path we haven't called
irq_enter() yet, so RCU doesn't know that we're about to exit
idle and properly warns that we're using RCU from an idle CPU.
Use trace_ipi_entry_rcuidle() instead of trace_ipi_entry() so
that RCU is informed about our exit from idle.

Cc: John Stultz <john.stultz@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # 3.17+
Fixes: 45ed695ac10a ("ARM64: add IPI tracepoints")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 4b2121bd7f9c..a1883bfdd9d6 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -693,7 +693,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 	struct pt_regs *old_regs = set_irq_regs(regs);
 
 	if ((unsigned)ipinr < NR_IPI) {
-		trace_ipi_entry(ipi_types[ipinr]);
+		trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
 	}
 
@@ -736,7 +736,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 	}
 
 	if ((unsigned)ipinr < NR_IPI)
-		trace_ipi_exit(ipi_types[ipinr]);
+		trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 	set_irq_regs(old_regs);
 }