From: Thomas Gleixner <tglx@linutronix.de>
To: Yunfeng Ye <yeyunfeng@huawei.com>
Cc: Bart Van Assche <bvanassche@acm.org>,
dsterba@suse.cz, bhelgaas@google.com,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
sakari.ailus@linux.intel.com,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
David Sterba <dsterba@suse.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] async: Let kfree() out of the critical area of the lock
Date: Fri, 15 Nov 2019 19:32:26 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.21.1911151931420.28787@nanos.tec.linutronix.de> (raw)
In-Reply-To: <9bfecf17-3c1b-414e-b271-4fd2d884faa3@huawei.com>
On Fri, 11 Oct 2019, Yunfeng Ye wrote:
> The async_lock is big global lock, and kfree() is not always cheap, it
> will increase lock contention. it's better let kfree() outside the lock
> to keep the critical area as short as possible.
>
> Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
> Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> ---
> v1 -> v2:
> - update the description
> - add "Reviewed-by"
>
> kernel/async.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/async.c b/kernel/async.c
> index 4f9c1d6..1de270d 100644
> --- a/kernel/async.c
> +++ b/kernel/async.c
> @@ -135,12 +135,12 @@ static void async_run_entry_fn(struct work_struct *work)
> list_del_init(&entry->domain_list);
> list_del_init(&entry->global_list);
>
> - /* 3) free the entry */
> - kfree(entry);
> atomic_dec(&entry_count);
> -
> spin_unlock_irqrestore(&async_lock, flags);
>
> + /* 3) free the entry */
> + kfree(entry);
> +
> /* 4) wake up any waiters */
> wake_up(&async_done);
The wakeup should happen before the kfree() for the very same reasons.
Thanks,
tglx
next prev parent reply other threads:[~2019-11-15 18:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-27 6:03 [PATCH v2] async: Let kfree() out of the critical area of the lock Yunfeng Ye
2019-10-11 8:11 ` Yunfeng Ye
2019-11-15 18:32 ` Thomas Gleixner [this message]
2019-11-19 3:01 ` Yunfeng Ye
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