Linux-USB Archive on lore.kernel.org
 help / color / Atom feed
From: Hayes Wang <hayeswang@realtek.com>
To: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	nic_swsd <nic_swsd@realtek.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: RE: [PATCH net-next 2/5] r8152: replace array with linking list for rx information
Date: Wed, 7 Aug 2019 04:34:24 +0000
Message-ID: <0835B3720019904CB8F7AA43166CEEB2F18D04FA@RTITMBSVM03.realtek.com.tw> (raw)
In-Reply-To: <20190806125342.4620a94f@cakuba.netronome.com>

Jakub Kicinski [mailto:jakub.kicinski@netronome.com]
[...]
> >  static int rtl_stop_rx(struct r8152 *tp)
> >  {
> > -	int i;
> > +	struct list_head *cursor, *next, tmp_list;
> > +	unsigned long flags;
> > +
> > +	INIT_LIST_HEAD(&tmp_list);
> >
> > -	for (i = 0; i < RTL8152_MAX_RX; i++)
> > -		usb_kill_urb(tp->rx_info[i].urb);
> > +	/* The usb_kill_urb() couldn't be used in atomic.
> > +	 * Therefore, move the list of rx_info to a tmp one.
> > +	 * Then, list_for_each_safe could be used without
> > +	 * spin lock.
> > +	 */
> 
> Would you mind explaining in a little more detail why taking the
> entries from the list for a brief period of time is safe?

Usually, it needs the spin lock before accessing the entry
of the list "tp->rx_info". However, for some reasons,
if we want to access the entry without spin lock, we
cloud move all entries to a local list temporally. Then,
we could make sure no other one could access the entries
included in the temporal local list.

For this case, when I move all entries to a temporal 
local list, no other one could access them. Therefore,
I could access the entries included in the temporal local
list without spin lock.


Best Regards,
Hayes



  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-06 11:17 [PATCH net-next 0/5] RX improve Hayes Wang
2019-08-06 11:18 ` [PATCH net-next 1/5] r8152: separate the rx buffer size Hayes Wang
2019-08-06 11:18 ` [PATCH net-next 2/5] r8152: replace array with linking list for rx information Hayes Wang
2019-08-06 19:53   ` Jakub Kicinski
2019-08-06 21:40     ` Jakub Kicinski
2019-08-07  4:34     ` Hayes Wang [this message]
2019-08-07 18:21       ` Jakub Kicinski
2019-08-06 11:18 ` [PATCH net-next 3/5] r8152: use alloc_pages for rx buffer Hayes Wang
2019-08-06 11:18 ` [PATCH net-next 4/5] r8152: support skb_add_rx_frag Hayes Wang
2019-08-06 22:08   ` Jakub Kicinski
2019-08-07  4:34     ` Hayes Wang
2019-08-06 11:18 ` [PATCH net-next 5/5] r8152: change rx_frag_head_sz and rx_max_agg_num dynamically Hayes Wang
2019-08-06 22:10   ` Jakub Kicinski
2019-08-07  7:12     ` Hayes Wang
2019-08-07 12:43       ` Maciej Fijalkowski
2019-08-08  1:40         ` Hayes Wang
2019-08-08  8:52     ` Hayes Wang
2019-08-08 11:49       ` Maciej Fijalkowski
2019-08-08 12:16         ` Hayes Wang
2019-08-08 18:43           ` Jakub Kicinski
2019-08-09  3:38             ` Hayes Wang
2019-08-09  4:51               ` David Miller

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0835B3720019904CB8F7AA43166CEEB2F18D04FA@RTITMBSVM03.realtek.com.tw \
    --to=hayeswang@realtek.com \
    --cc=jakub.kicinski@netronome.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=nic_swsd@realtek.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-USB Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-usb/0 linux-usb/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-usb linux-usb/ https://lore.kernel.org/linux-usb \
		linux-usb@vger.kernel.org
	public-inbox-index linux-usb

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-usb


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git