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authorStephen Boyd <sboyd@codeaurora.org>2015-06-19 21:37:56 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-06-29 11:02:55 +0100
commit398f74569cebbf06bc6b069442bcd0e9616ca465 (patch)
treea27eece3fe448444a64b0a704dc02dd40883fb9e /arch/arm/kernel
parentb953c0d234bc72e8489d3bf51a276c5c4ec85345 (diff)
ARM: 8393/1: smp: Fix suspicious RCU usage with ipi tracepoints
John Stultz reports an RCU splat on boot with ARM ipi trace events enabled. =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc7-00033-gb5bed2f #153 Not tainted ------------------------------- include/trace/events/ipi.h:68 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/0/0. stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.0-rc7-00033-gb5bed2f #153 Hardware name: Qualcomm (Flattened Device Tree) [<c0216b08>] (unwind_backtrace) from [<c02136e8>] (show_stack+0x10/0x14) [<c02136e8>] (show_stack) from [<c075e678>] (dump_stack+0x70/0xbc) [<c075e678>] (dump_stack) from [<c0215a80>] (handle_IPI+0x428/0x604) [<c0215a80>] (handle_IPI) from [<c020942c>] (gic_handle_irq+0x54/0x5c) [<c020942c>] (gic_handle_irq) from [<c0766604>] (__irq_svc+0x44/0x7c) Exception stack(0xc09f3f48 to 0xc09f3f90) 3f40: 00000001 00000001 00000000 c09f73b8 c09f4528 c0a5de9c 3f60: c076b4f0 00000000 00000000 c09ef108 c0a5cec1 00000001 00000000 c09f3f90 3f80: c026bf60 c0210ab8 20000113 ffffffff [<c0766604>] (__irq_svc) from [<c0210ab8>] (arch_cpu_idle+0x20/0x3c) [<c0210ab8>] (arch_cpu_idle) from [<c02647f0>] (cpu_startup_entry+0x2c0/0x5dc) [<c02647f0>] (cpu_startup_entry) from [<c099bc1c>] (start_kernel+0x358/0x3c4) [<c099bc1c>] (start_kernel) from [<8020807c>] (0x8020807c) 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. Fixes: 365ec7b17327 ("ARM: add IPI tracepoints") Reported-by: John Stultz <john.stultz@linaro.org> Tested-by: John Stultz <john.stultz@linaro.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r--arch/arm/kernel/smp.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index cca5b8758185..f11d82527076 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -576,7 +576,7 @@ 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]);
}
@@ -635,7 +635,7 @@ 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);
}