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SubjectRe: [PATCH v5 5/6] dcdbas: make use of smp_call_on_cpu()
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On 06/04/16 16:17, Juergen Gross wrote:
> Use smp_call_on_cpu() to raise SMI on cpu 0.
> Make call secure by adding get_online_cpus() to avoid e.g. suspend
> resume cycles in between.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>

Could please some maintainer comment on this patch?


Juergen

> ---
> V4: add call to get_online_cpus()
> ---
> drivers/firmware/dcdbas.c | 51 ++++++++++++++++++++++++-----------------------
> 1 file changed, 26 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c
> index 829eec8..2fe1a13 100644
> --- a/drivers/firmware/dcdbas.c
> +++ b/drivers/firmware/dcdbas.c
> @@ -23,6 +23,7 @@
> #include <linux/platform_device.h>
> #include <linux/dma-mapping.h>
> #include <linux/errno.h>
> +#include <linux/cpu.h>
> #include <linux/gfp.h>
> #include <linux/init.h>
> #include <linux/kernel.h>
> @@ -238,33 +239,14 @@ static ssize_t host_control_on_shutdown_store(struct device *dev,
> return count;
> }
>
> -/**
> - * dcdbas_smi_request: generate SMI request
> - *
> - * Called with smi_data_lock.
> - */
> -int dcdbas_smi_request(struct smi_cmd *smi_cmd)
> +static int raise_smi(void *par)
> {
> - cpumask_var_t old_mask;
> - int ret = 0;
> + struct smi_cmd *smi_cmd = par;
>
> - if (smi_cmd->magic != SMI_CMD_MAGIC) {
> - dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n",
> - __func__);
> - return -EBADR;
> - }
> -
> - /* SMI requires CPU 0 */
> - if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
> - return -ENOMEM;
> -
> - cpumask_copy(old_mask, &current->cpus_allowed);
> - set_cpus_allowed_ptr(current, cpumask_of(0));
> if (smp_processor_id() != 0) {
> dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n",
> __func__);
> - ret = -EBUSY;
> - goto out;
> + return -EBUSY;
> }
>
> /* generate SMI */
> @@ -280,9 +262,28 @@ int dcdbas_smi_request(struct smi_cmd *smi_cmd)
> : "memory"
> );
>
> -out:
> - set_cpus_allowed_ptr(current, old_mask);
> - free_cpumask_var(old_mask);
> + return 0;
> +}
> +/**
> + * dcdbas_smi_request: generate SMI request
> + *
> + * Called with smi_data_lock.
> + */
> +int dcdbas_smi_request(struct smi_cmd *smi_cmd)
> +{
> + int ret;
> +
> + if (smi_cmd->magic != SMI_CMD_MAGIC) {
> + dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n",
> + __func__);
> + return -EBADR;
> + }
> +
> + /* SMI requires CPU 0 */
> + get_online_cpus();
> + ret = smp_call_on_cpu(0, raise_smi, smi_cmd, true);
> + put_online_cpus();
> +
> return ret;
> }
>
>

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