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Date: Wed, 3 Jan 2024 13:04:14 +0100
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Subject: Re: [PATCH] list: Add hlist_count_nodes()
To: Marco Elver <elver@google.com>
Cc: linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
 Lucas De Marchi <lucas.demarchi@intel.com>,
 Jani Nikula <jani.nikula@intel.com>,
 Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
 Ingo Molnar <mingo@kernel.org>
References: <20240103090241.164817-1-pierre.gondois@arm.com>
 <CANpmjNPsBUJy6tkOdRSJyWrS9CMUOQhQyb7_hwmw68pjjiEDWQ@mail.gmail.com>
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From: Pierre Gondois <pierre.gondois@arm.com>
In-Reply-To: <CANpmjNPsBUJy6tkOdRSJyWrS9CMUOQhQyb7_hwmw68pjjiEDWQ@mail.gmail.com>
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Hello Marco,

On 1/3/24 12:25, Marco Elver wrote:
> On Wed, 3 Jan 2024 at 10:02, Pierre Gondois <pierre.gondois@arm.com> wrote:
>>
>> Add a function to count nodes in a hlist. hlist_count_nodes()
>> is similar to list_count_nodes().
>>
>> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
> 
> Is this patch part of another patch series? As-is, this will be dead
> code, and there's no guarantee someone will just go and delete it in
> future. Although this function looks useful, we also should avoid
> adding new dead code.

The function is indeed not used in the project right now. I needed
it for a private module. If it helps integrating the function and
not make it dead code, maybe I could add usages at the following
places:
- drivers/gpu/drm/drm_hashtab.c::print_binder_node_nilocked()
- drivers/md/bcache/sysfs.c::bch_cache_max_chain()

Regards,
Pierre

> 
>> ---
>>   include/linux/list.h | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/include/linux/list.h b/include/linux/list.h
>> index 1837caedf723..0f1b1d4a2e2e 100644
>> --- a/include/linux/list.h
>> +++ b/include/linux/list.h
>> @@ -1175,4 +1175,19 @@ static inline void hlist_move_list(struct hlist_head *old,
>>               pos && ({ n = pos->member.next; 1; });                     \
>>               pos = hlist_entry_safe(n, typeof(*pos), member))
>>
>> +/**
>> + * hlist_count_nodes - count nodes in the hlist
>> + * @head:      the head for your hlist.
>> + */
>> +static inline size_t hlist_count_nodes(struct hlist_head *head)
>> +{
>> +       struct hlist_node *pos;
>> +       size_t count = 0;
>> +
>> +       hlist_for_each(pos, head)
>> +               count++;
>> +
>> +       return count;
>> +}
>> +
>>   #endif
>> --
>> 2.25.1
>>