Re: [PATCH 25/26] kprobes: Convert to raw_spinlocks

[Frederic Weisbecker]

On Mon, Jan 11, 2010 at 10:26:55PM +0100, John Kacur wrote:
> Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks.
> 
> See also dc23e836d8d25fe5aa4057d54dae2094fbc614f6
> 
> Signed-off-by: John Kacur <jkacur@xxxxxxxxxx>
> ---
>  include/linux/kprobes.h |    2 +-
>  kernel/kprobes.c        |   34 +++++++++++++++++-----------------
>  2 files changed, 18 insertions(+), 18 deletions(-)
> 
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 1b672f7..620df87 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -170,7 +170,7 @@ struct kretprobe {
>  	int nmissed;
>  	size_t data_size;
>  	struct hlist_head free_instances;
> -	spinlock_t lock;
> +	raw_spinlock_t lock;
>  };


Indeed, this lock seems to be taken when a probe triggers, which
can happen in about every places/context.

Please add a comment to explain this though.

(Adding Masami in Cc).

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