linux-kernel - Re: [PATCH] remoteproc: core: Remove state checking before changing state

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Message-ID: <CANLsYkyHVcoF_fM836vES9gsj0b39aqC6s=9UNeRuAQMZjggRQ@mail.gmail.com>
Date:   Thu, 24 Mar 2022 10:53:27 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Shengjiu Wang <shengjiu.wang@....com>
Cc:     bjorn.andersson@...aro.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, shengjiu.wang@...il.com
Subject: Re: [PATCH] remoteproc: core: Remove state checking before changing state

On Wed, 23 Mar 2022 at 03:42, Shengjiu Wang <shengjiu.wang@....com> wrote:
>
> There is no mutex protecting of these state checking, which
> can't garantee there is no another instance is trying to do
> same operation.
>
> The reference counter rproc->power is used to manage state
> changing and there is mutex protection in each operation
> function for multi instance case.
>
> So remove this state checking in rproc_cdev_write() and
> state_store(), just let reference counter rproc->power to
> manage the behaviors.
>
> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> ---
>  drivers/remoteproc/remoteproc_cdev.c  | 11 -----------
>  drivers/remoteproc/remoteproc_sysfs.c | 11 -----------
>  2 files changed, 22 deletions(-)
>
> diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c
> index 906ff3c4dfdd..687f205fd70a 100644
> --- a/drivers/remoteproc/remoteproc_cdev.c
> +++ b/drivers/remoteproc/remoteproc_cdev.c
> @@ -32,21 +32,10 @@ static ssize_t rproc_cdev_write(struct file *filp, const char __user *buf, size_
>                 return -EFAULT;
>
>         if (!strncmp(cmd, "start", len)) {
> -               if (rproc->state == RPROC_RUNNING ||
> -                   rproc->state == RPROC_ATTACHED)
> -                       return -EBUSY;
> -
>                 ret = rproc_boot(rproc);
>         } else if (!strncmp(cmd, "stop", len)) {
> -               if (rproc->state != RPROC_RUNNING &&
> -                   rproc->state != RPROC_ATTACHED)
> -                       return -EINVAL;
> -
>                 ret = rproc_shutdown(rproc);
>         } else if (!strncmp(cmd, "detach", len)) {
> -               if (rproc->state != RPROC_ATTACHED)
> -                       return -EINVAL;
> -
>                 ret = rproc_detach(rproc);
>         } else {
>                 dev_err(&rproc->dev, "Unrecognized option\n");
> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> index 51a04bc6ba7a..8c7ea8922638 100644
> --- a/drivers/remoteproc/remoteproc_sysfs.c
> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> @@ -194,23 +194,12 @@ static ssize_t state_store(struct device *dev,
>         int ret = 0;
>
>         if (sysfs_streq(buf, "start")) {
> -               if (rproc->state == RPROC_RUNNING ||
> -                   rproc->state == RPROC_ATTACHED)
> -                       return -EBUSY;
> -

As per my previous comment the above conditions need to be moved into
rproc_boot().

>                 ret = rproc_boot(rproc);
>                 if (ret)
>                         dev_err(&rproc->dev, "Boot failed: %d\n", ret);
>         } else if (sysfs_streq(buf, "stop")) {
> -               if (rproc->state != RPROC_RUNNING &&
> -                   rproc->state != RPROC_ATTACHED)
> -                       return -EINVAL;
> -
>                 ret = rproc_shutdown(rproc);
>         } else if (sysfs_streq(buf, "detach")) {
> -               if (rproc->state != RPROC_ATTACHED)
> -                       return -EINVAL;
> -

This patch should have been part of a patch series with your other
work sent on March 18th[1].

Thanks,
Mathieu

[1]. [PATCH] remoteproc: core: check rproc->power value before decreasing it

>                 ret = rproc_detach(rproc);
>         } else {
>                 dev_err(&rproc->dev, "Unrecognised option: %s\n", buf);
> --
> 2.17.1
>