linux-kernel - Re: [PATCH v2 03/45] notifier: Add atomic/blocking_notifier_has_unique

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Message-ID: <YXqCz/utp2DFJJ45@smile.fi.intel.com>
Date:   Thu, 28 Oct 2021 14:00:31 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Lee Jones <lee.jones@...aro.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
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Subject: Re: [PATCH v2 03/45] notifier: Add
 atomic/blocking_notifier_has_unique_priority()

On Thu, Oct 28, 2021 at 12:16:33AM +0300, Dmitry Osipenko wrote:
> Add atomic/blocking_notifier_has_unique_priority() helpers which return
> true if given handler has unique priority.

...

> +/**
> + *	atomic_notifier_has_unique_priority - Checks whether notifier's priority is unique
> + *	@nh: Pointer to head of the atomic notifier chain
> + *	@n: Entry in notifier chain to check
> + *
> + *	Checks whether there is another notifier in the chain with the same priority.
> + *	Must be called in process context.
> + *
> + *	Returns true if priority is unique, false otherwise.

Why this indentation?

> + */
> +bool atomic_notifier_has_unique_priority(struct atomic_notifier_head *nh,
> +		struct notifier_block *n)
> +{
> +	struct notifier_block **nl = &nh->head;
> +	unsigned long flags;
> +	bool ret = true;
> +
> +	spin_lock_irqsave(&nh->lock, flags);
> +
> +	while ((*nl) != NULL && (*nl)->priority >= n->priority) {

' != NULL' is redundant.

> +		if ((*nl)->priority == n->priority && (*nl) != n) {
> +			ret = false;
> +			break;
> +		}
> +
> +		nl = &((*nl)->next);
> +	}
> +
> +	spin_unlock_irqrestore(&nh->lock, flags);
> +
> +	return ret;
> +}

...

> +	/*
> +	 * This code gets used during boot-up, when task switching is
> +	 * not yet working and interrupts must remain disabled.  At

One space is enough.

> +	 * such times we must not call down_write().
> +	 */

> +	while ((*nl) != NULL && (*nl)->priority >= n->priority) {

' != NULL' is not needed.

> +		if ((*nl)->priority == n->priority && (*nl) != n) {
> +			ret = false;
> +			break;
> +		}
> +
> +		nl = &((*nl)->next);
> +	}

-- 
With Best Regards,
Andy Shevchenko