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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: 45ed695ac1 ("ARM64: add IPI tracepoints")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
hifive-unleashed-5.1
Stephen Boyd 2015-06-24 13:14:18 -07:00 committed by Catalin Marinas
parent 86dca36e6b
commit be081d9bf3
1 changed files with 2 additions and 2 deletions
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4
arch/arm64/kernel/smp.c
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@ -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);
}