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| author | Stephen Boyd <sboyd@codeaurora.org> | 2015-06-19 23:37:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-08-03 19:29:19 +0300 |
| commit | ec5ea3004ddc46c09c6805119cedb7b8f516b997 (patch) | |
| tree | 005d4f1a81e69fe91ac54567048cf0fa4659b273 | |
| parent | a0238976f43770541b4f899415f0e75800df2d4a (diff) | |
| download | linux-ec5ea3004ddc46c09c6805119cedb7b8f516b997.tar.xz | |
ARM: 8393/1: smp: Fix suspicious RCU usage with ipi tracepoints
commit 398f74569cebbf06bc6b069442bcd0e9616ca465 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm/kernel/smp.c | 4 |
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); } |