| From be081d9bf3e163a9ed1ca2f0f14f08424c7f9016 Mon Sep 17 00:00:00 2001 |
| From: Stephen Boyd <sboyd@codeaurora.org> |
| Date: Wed, 24 Jun 2015 13:14:18 -0700 |
| Subject: ARM64: smp: Fix suspicious RCU usage with ipi tracepoints |
| |
| From: Stephen Boyd <sboyd@codeaurora.org> |
| |
| commit be081d9bf3e163a9ed1ca2f0f14f08424c7f9016 upstream. |
| |
| 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> |
| Fixes: 45ed695ac10a ("ARM64: add IPI tracepoints") |
| Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> |
| Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm64/kernel/smp.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/arch/arm64/kernel/smp.c |
| +++ b/arch/arm64/kernel/smp.c |
| @@ -569,7 +569,7 @@ void handle_IPI(int ipinr, struct pt_reg |
| 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]); |
| } |
| |
| @@ -612,7 +612,7 @@ void handle_IPI(int ipinr, struct pt_reg |
| } |
| |
| if ((unsigned)ipinr < NR_IPI) |
| - trace_ipi_exit(ipi_types[ipinr]); |
| + trace_ipi_exit_rcuidle(ipi_types[ipinr]); |
| set_irq_regs(old_regs); |
| } |
| |
