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    SubjectRe: [PATCH 2/3] led-triggers: use atomic kzalloc during led trigger registering
    On Thu, Mar 08, 2012 at 05:11:02PM +0800, Bryan Wu wrote:
    > kzalloc might cause sleep and will generate some warning detected by lockdep,
    > when call led_trigger_register_simple on each cpu cores in SMP. This patch fix
    > this.
    The obvious (and IMHO better) alternative is to call
    led_trigger_register_simple from non-atomic context.

    For registering this should be OK, shouldn't it?

    Best regards
    Uwe

    >
    > [ 1.999938] ------------[ cut here ]------------
    > [ 2.004791] WARNING: at kernel/lockdep.c:2664 lockdep_trace_alloc+0xd8/0xf0()
    > [ 2.012298] Modules linked in:
    > [ 2.015563] [<c001b0cc>] (unwind_backtrace+0x0/0xf0) from [<c0052408>] (warn_slowpath_common+0x4c/0x64)
    > [ 2.025451] [<c0052408>] (warn_slowpath_common+0x4c/0x64) from [<c005243c>] (warn_slowpath_null+0x1c/0x24)
    > [ 2.035583] [<c005243c>] (warn_slowpath_null+0x1c/0x24) from [<c008be28>] (lockdep_trace_alloc+0xd8/0xf0)
    > [ 2.045684] [<c008be28>] (lockdep_trace_alloc+0xd8/0xf0) from [<c00feeb4>] (kmem_cache_alloc_trace+0x2c/0x148)
    > [ 2.056213] [<c00feeb4>] (kmem_cache_alloc_trace+0x2c/0x148) from [<c03770a0>] (led_trigger_register_simple+0x20/0x74)
    > [ 2.067474] [<c03770a0>] (led_trigger_register_simple+0x20/0x74) from [<c0627a30>] (ledtrig_cpu_register+0x4c/0x8c)
    > [ 2.078460] [<c0627a30>] (ledtrig_cpu_register+0x4c/0x8c) from [<c0094ca4>] (generic_smp_call_function_single_interrupt+0xcc/0x138)
    > [ 2.090911] [<c0094ca4>] (generic_smp_call_function_single_interrupt+0xcc/0x138) from [<c0008408>] (do_IPI+0xb0/0x128)
    > [ 2.102172] [<c0008408>] (do_IPI+0xb0/0x128) from [<c045921c>] (__irq_svc+0x3c/0x100)
    > [ 2.110412] Exception stack(0xc07adf70 to 0xc07adfb8)
    > [ 2.115722] df60: c07c80f8 0000fb45 00000000 c07c80f8
    > [ 2.124328] df80: c07ac000 c0837be4 c0464b64 c07c9d8c 00000000 411fc092 00000000 00000000
    > [ 2.132934] dfa0: c0649760 c07adfb8 c07c5c58 c0014d50 20000013 ffffffff
    > [ 2.139892] [<c045921c>] (__irq_svc+0x3c/0x100) from [<c0014d50>] (default_idle+0x30/0x38)
    > [ 2.148590] [<c0014d50>] (default_idle+0x30/0x38) from [<c0014f74>] (cpu_idle+0xb4/0xf4)
    > [ 2.157135] [<c0014f74>] (cpu_idle+0xb4/0xf4) from [<c0602778>] (start_kernel+0x2a8/0x2fc)
    > [ 2.165832] [<c0602778>] (start_kernel+0x2a8/0x2fc) from [<80008040>] (0x80008040)
    > [ 2.173797] ---[ end trace 97549d21d8dad3f5 ]---
    >
    > Signed-off-by: Bryan Wu <bryan.wu@canonical.com>
    > ---
    > drivers/leds/led-triggers.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)
    >
    > diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
    > index 46b4c76..74d0ba7 100644
    > --- a/drivers/leds/led-triggers.c
    > +++ b/drivers/leds/led-triggers.c
    > @@ -255,7 +255,7 @@ void led_trigger_register_simple(const char *name, struct led_trigger **tp)
    > struct led_trigger *trigger;
    > int err;
    >
    > - trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
    > + trigger = kzalloc(sizeof(struct led_trigger), GFP_ATOMIC);
    >
    > if (trigger) {
    > trigger->name = name;
    > --
    > 1.7.9
    >
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
    >

    --
    Pengutronix e.K. | Uwe Kleine-König |
    Industrial Linux Solutions | http://www.pengutronix.de/ |
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