Re: [PATCH v2 4/5] blk-iocost: fix sleeping in atomic context warnning

Tejun Heo
2022-11-22T21:10:35Z

On Thu, Nov 17, 2022 at 07:28:50PM +0800, Yu Kuai wrote:
> Hi, Tejun!
>
> 在 2022/11/15 6:07, Tejun Heo 写道:
>
> >
> > Any chance I can persuade you into updating match_NUMBER() helpers to not
> > use match_strdup()? They can easily disable irq/preemption and use percpu
> > buffers and we won't need most of this patchset.
>
> Does the following patch match your proposal?
>
> diff --git a/lib/parser.c b/lib/parser.c
> index bcb23484100e..ded652471919 100644
> --- a/lib/parser.c
> +++ b/lib/parser.c
> @@ -11,6 +11,24 @@
> #include <linux/slab.h>
> #include <linux/string.h>
>
> +#define U64_MAX_SIZE 20
> +
> +static DEFINE_PER_CPU(char, buffer[U64_MAX_SIZE]);
> +
> +static char *get_buffer(void)
> +{
> + preempt_disable();
> + local_irq_disable();
> +
> + return this_cpu_ptr(buffer);
> +}
> +
> +static void put_buffer(void)
> +{
> + local_irq_enable();
> + preempt_enable();
> +}
> +
>
> Then match_strdup() and kfree() in match_NUMBER() can be replaced with
> get_buffer() and put_buffer().

Sorry about the late reply. Yeah, something like this.

Thanks.

--
tejun