From: Chen Gang <gang.chen.5i5j@gmail.com>
To: Joe Perches <joe@perches.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
"John W. Linville" <linville@tuxdriver.com>,
rkuo <rkuo@codeaurora.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
David Miller <davem@davemloft.net>,
linux-wireless@vger.kernel.org, netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH] net: mac80211: tx.c: be sure of 'sdata->vif.type' must be NL80211_IFTYPE_AP when be in NL80211_IFTYPE_AP case
Date: Sun, 01 Dec 2013 07:48:37 +0800 [thread overview]
Message-ID: <529A7955.9010507@gmail.com> (raw)
In-Reply-To: <1385843940.2664.4.camel@joe-AO722>
On 12/01/2013 04:39 AM, Joe Perches wrote:
> On Sat, 2013-11-30 at 21:08 +0100, Johannes Berg wrote:
>> On Sat, 2013-11-30 at 22:02 +0800, Chen Gang wrote:
>>> - fall-through is obvious (although I did not notice it, originally).
>>>
>>> - Check 'A' again just near by "case A" seems a little strange.
>>>
>>> - Some compilers aren't quit smart enough to know 'chanctx_conf' is OK.
>>
>> I know. If you have any good ideas of how to make it more obvious to the
>> compiler, I'm all ears, I just don't like any of the solutions offered
>> so far (and you aren't the first to do so either) :-)
>>
OK, thanks.
>> FWIW, I find the label to be odd because if you're familiar with the
>> code then AP/AP_VLAN *should* be identical except for two special things
>> that are now linearly & neatly handled in the code (the first being the
>> 4-addr station, the second the chanctx assignment which always has to be
>> done regardless of 4-addr). IMHO the == check after case should be
>> enough to make a human reader take a closer look. I understand that you
>> didn't and that's OK since you were just trying to squelch compile
>> warnings, but I don't see that this one warrants much attention.
>
> The label/test could be moved to save a couple of lines
> of duplicated code.
>
Hmm... for me, it must be an implementation which can satisfy all of us.
If ieee80211_subif_start_xmit() is not performance sensitive (I guess
so), we can use some short static functions instead of some code blocks
within ieee80211_subif_start_xmit().
- ieee80211_subif_start_xmit() is a long function (600+ lines).
- use short static function can share some code.
- if code can be shared, the work flow can be more clearer too (don't
need fall-through or goto).
And I guess, the implementation below can cause panic when
"sdata->vif.type == NL80211_IFTYPE_AP_VLAN". :-(
> Maybe:
>
> net/mac80211/tx.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index 70b5a05..b2160f4 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -1777,18 +1777,16 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
> }
> ap_sdata = container_of(sdata->bss, struct ieee80211_sub_if_data,
> u.ap);
> - chanctx_conf = rcu_dereference(ap_sdata->vif.chanctx_conf);
> - if (!chanctx_conf)
> - goto fail_rcu;
> - band = chanctx_conf->def.chan->band;
> - if (sta)
> - break;
> /* fall through */
> case NL80211_IFTYPE_AP:
> - if (sdata->vif.type == NL80211_IFTYPE_AP)
> - chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
> + chanctx_conf = rcu_dereference(ap_sdata->vif.chanctx_conf);
> if (!chanctx_conf)
> goto fail_rcu;
> + if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
> + band = chanctx_conf->def.chan->band;
> + if (sta)
> + break;
> + }
> fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
> /* DA BSSID SA */
> memcpy(hdr.addr1, skb->data, ETH_ALEN);
>
>
--
Chen Gang
next prev parent reply other threads:[~2013-11-30 23:48 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 4:57 [PATCH] arch: hexagon: Kconfig: add HAVE_DMA_ATTR in Kconfig and remove "linux/dma-mapping.h" from "asm/dma-mapping.h" Chen Gang
2013-11-25 1:19 ` rkuo
2013-11-25 2:39 ` [PATCH 0/2] arch: hexagon: include: asm: add prefix "vm_" for all enum members in "hexagon_vm.h" Chen Gang
2013-11-25 2:40 ` [PATCH 1/2] " Chen Gang
2013-11-25 2:41 ` [PATCH 2/2] arch: hexagon: include: asm: use 'affinity' instead of 'locdis' for __vmintop_affinity() " Chen Gang
2013-11-28 8:51 ` [PATCH v2] arch: hexagon: include: asm: add prefix "hvm[ci]_" for all enum members " Chen Gang
2013-12-06 18:22 ` rkuo
2013-11-26 4:36 ` [PATCH 1/2] arch: hexagon: include: asm: add prefix "vm_" " Chen Gang
2013-11-27 2:29 ` [PATCH] drivers: scsi: scsi_lib.c: add prefix "SCSILIB_" to macro "SP" Chen Gang
2013-12-01 16:17 ` Bart Van Assche
2013-12-02 0:34 ` Chen Gang
2013-12-02 0:49 ` James Bottomley
2013-12-02 10:14 ` Chen Gang
2013-12-02 21:32 ` rkuo
2013-12-03 11:42 ` Chen Gang
2013-12-04 2:42 ` [PATCH v2] drivers: scsi: scsi_lib.c: use SG_POOL instead of SP Chen Gang
2013-11-27 3:01 ` [PATCH] drivers: staging: ft1000: ft1000-usb: initialize 'status' with STATUS_SUCCESS in request_code_segment() Chen Gang
2013-11-27 9:18 ` Josh Triplett
2013-11-27 9:27 ` Chen Gang
2013-12-04 7:31 ` Chen Gang
2013-11-27 3:17 ` [PATCH] drivers: staging: media: go7007: go7007-usb.c use pr_*() instead of dev_*() before 'go' initialized in go7007_usb_probe() Chen Gang
2013-11-27 3:21 ` Joe Perches
2013-11-27 3:40 ` Chen Gang
2013-11-27 3:48 ` [PATCH v2] " Chen Gang
2013-11-27 4:03 ` Greg KH
2013-11-27 4:24 ` Chen Gang
2013-11-27 10:43 ` Dan Carpenter
2013-11-28 1:47 ` Chen Gang
2013-11-27 3:40 ` [PATCH] drivers: staging: ft1000: ft1000-usb: ft1000_debug.c: check return value of get_user() in ft1000_ioctl() Chen Gang
2013-11-27 4:53 ` [PATCH] net: mac80211: tx.c: be sure of 'sdata->vif.type' must be NL80211_IFTYPE_AP when be in NL80211_IFTYPE_AP case Chen Gang
2013-11-29 15:38 ` Johannes Berg
2013-11-30 11:59 ` Chen Gang
2013-11-30 12:53 ` Johannes Berg
2013-11-30 13:50 ` Chen Gang
2013-11-30 14:02 ` Chen Gang
2013-11-30 20:08 ` Johannes Berg
2013-11-30 20:39 ` Joe Perches
2013-11-30 23:48 ` Chen Gang [this message]
2013-11-30 23:59 ` Chen Gang
2013-12-01 9:37 ` Johannes Berg
2013-12-01 11:50 ` Chen Gang
2013-12-01 9:35 ` Johannes Berg
2013-12-01 22:38 ` Joe Perches
2013-12-02 0:45 ` Chen Gang
2013-12-02 14:48 ` Johannes Berg
2013-12-04 2:12 ` Chen Gang
2013-12-04 8:04 ` Johannes Berg
2013-12-04 8:41 ` Chen Gang
2013-12-04 8:49 ` Johannes Berg
2013-12-04 9:00 ` Chen Gang
2013-11-27 5:28 ` [PATCH] arch: hexagon: include: uapi: asm: setup.h add swith macro __KERNEL__ Chen Gang
2013-12-06 18:21 ` rkuo
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