Re: [PATCH v2] staging: wfx: use container_of() to get vif

From: Stefano Brivio
Date: Fri Apr 08 2022 - 01:43:43 EST

Hi Jaehee,

Congrats, almost there! This wasn't necessarily an easy change.

A general comment first: please wait a bit longer between re-postings.
I received the first patch at 21:50 UTC+2 (my local time), and the
second one at 5:23 UTC+2.

I could have shared most of the comments below already on your first
patch, if only I had time to read it. I think something between 12 to
15 hours would be appropriate.

Now, to the patch:

On Thu, 7 Apr 2022 23:23:49 -0400
Jaehee Park <jhpark1013@xxxxxxxxx> wrote:

> Use container_of() to get vif. This improves the code in two ways:
> [1] it speeds up the compilation because container_of() saves steps to
> retrieve vif (the representation of ieee80211_vif), and

"[1] " looks like a reference, perhaps use "- " or "1. " instead.

It would be good to follow the guidelines at:
https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-changes

...starting from the problem description, even if it's a bit obvious
here. For example:

Currently, upon virtual interface creation,
wfx_add_interface() stores a references to the
corresponding struct ieee80211_vif in private data, for later
usage. This is not needed as ...

Use container_of() instead. This...

> [2] it eliminates the need to define multiple pointers. Previously,
> after setting the pointer to drv_priv, another pointer had to be
> defined by vif in struct wfx_vif to point back to ieee80211_vif.
> Remove vif from the struct wfx_vif, define a macro wvif_to_vif(ptr)
> for container_of(), and replace all wvif->vif with the newly defined
> container_of() construct.
>
> Signed-off-by: Jaehee Park <jhpark1013@xxxxxxxxx>
> ---
> Note:
> This is a revised patch to sequence the wfx.h file (with the new defines) to show up first on the diff, which makes the ordering of the diff more logical.

Trim your lines at something between 70 and 76 columns, even if it's
not part of the commit message -- that will make it easier to reply.

One additional note given where this patch will need to go: for net and
net-next trees, you're required to describe the change log at the end
of the commit message itself. That's an exception compared to other
trees (including staging -- where adding the commit log here is
appropriate).

> Questions:
> - These changes had built without errors for me but it would be great if someone can test it on the actual hardware.
> - We noticed that the development of the wfx driver is happening in the netdev tree instead of Greg's tree. Do you suggest that I use the net-next tree for this change? 
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/log/drivers/staging/wfx
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/log/drivers/staging/wfx
>
> drivers/staging/wfx/wfx.h | 3 ++-
> drivers/staging/wfx/data_rx.c | 4 ++--
> drivers/staging/wfx/data_tx.c | 2 +-
> drivers/staging/wfx/key.c | 3 +--
> drivers/staging/wfx/queue.c | 2 +-
> drivers/staging/wfx/scan.c | 6 ++---
> drivers/staging/wfx/sta.c | 45 ++++++++++++++++-------------------
> 7 files changed, 31 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/staging/wfx/wfx.h b/drivers/staging/wfx/wfx.h
> index 6594cc647c2f..78f2a416fe4f 100644
> --- a/drivers/staging/wfx/wfx.h
> +++ b/drivers/staging/wfx/wfx.h
> @@ -25,6 +25,8 @@
> #define USEC_PER_TXOP 32 /* see struct ieee80211_tx_queue_params */
> #define USEC_PER_TU 1024
>
> +#define wvif_to_vif(ptr)(container_of((void *)ptr, struct ieee80211_vif, drv_priv))

On top of what Greg said (you're missing a space there) the line is also
too long, you can split it by doing something like:

#define wvif_to_vif(...) \
container_of(...)

also:

- parentheses around container_of() are not necessary

- "ptr"? It's obvious that it's a pointer, given the cast. "wvif" would
be more descriptive

> +
> struct wfx_hwbus_ops;
>
> struct wfx_dev {
> @@ -61,7 +63,6 @@ struct wfx_dev {
>
> struct wfx_vif {
> struct wfx_dev *wdev;
> - struct ieee80211_vif *vif;
> struct ieee80211_channel *channel;
> int id;
>
> diff --git a/drivers/staging/wfx/data_rx.c b/drivers/staging/wfx/data_rx.c
> index a4b5ffe158e4..98c2223089b8 100644
> --- a/drivers/staging/wfx/data_rx.c
> +++ b/drivers/staging/wfx/data_rx.c
> @@ -24,12 +24,12 @@ static void wfx_rx_handle_ba(struct wfx_vif *wvif, struct ieee80211_mgmt *mgmt)
> case WLAN_ACTION_ADDBA_REQ:
> params = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
> tid = (params & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
> - ieee80211_start_rx_ba_session_offl(wvif->vif, mgmt->sa, tid);
> + ieee80211_start_rx_ba_session_offl(wvif_to_vif(wvif), mgmt->sa, tid);

Staying under 80 columns is preferred:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bdc48fa11e46f867ea4d75fa59ee87a7f48be144

but checkpatch.pl won't report this. Perhaps to_vif() would be
descriptive enough, or you could also just split this line.

Or, even better, especially if you have several usages in a function:
just grab one reference to vif at the beginning of the function, and
use that instead.

> break;
> case WLAN_ACTION_DELBA:
> params = le16_to_cpu(mgmt->u.action.u.delba.params);
> tid = (params & IEEE80211_DELBA_PARAM_TID_MASK) >> 12;
> - ieee80211_stop_rx_ba_session_offl(wvif->vif, mgmt->sa, tid);
> + ieee80211_stop_rx_ba_session_offl(wvif_to_vif(wvif), mgmt->sa, tid);

Same here.

> break;
> }
> }
> diff --git a/drivers/staging/wfx/data_tx.c b/drivers/staging/wfx/data_tx.c
> index e07381b2ff4d..fd79e03a08c5 100644
> --- a/drivers/staging/wfx/data_tx.c
> +++ b/drivers/staging/wfx/data_tx.c
> @@ -216,7 +216,7 @@ static u8 wfx_tx_get_link_id(struct wfx_vif *wvif, struct ieee80211_sta *sta,
>
> if (sta_priv && sta_priv->link_id)
> return sta_priv->link_id;
> - if (wvif->vif->type != NL80211_IFTYPE_AP)
> + if (wvif_to_vif(wvif)->type != NL80211_IFTYPE_AP)
> return 0;
> if (is_multicast_ether_addr(da))
> return 0;
> diff --git a/drivers/staging/wfx/key.c b/drivers/staging/wfx/key.c
> index 8f23e8d42bd4..71b1fca70248 100644
> --- a/drivers/staging/wfx/key.c
> +++ b/drivers/staging/wfx/key.c
> @@ -174,7 +174,7 @@ static int wfx_add_key(struct wfx_vif *wvif, struct ieee80211_sta *sta,
> k.type = fill_tkip_pair(&k.key.tkip_pairwise_key, key, sta->addr);
> else
> k.type = fill_tkip_group(&k.key.tkip_group_key, key, &seq,
> - wvif->vif->type);
> + wvif_to_vif(wvif)->type);
> } else if (key->cipher == WLAN_CIPHER_SUITE_CCMP) {
> if (pairwise)
> k.type = fill_ccmp_pair(&k.key.aes_pairwise_key, key, sta->addr);
> @@ -224,4 +224,3 @@ int wfx_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd, struct ieee80211_
> mutex_unlock(&wvif->wdev->conf_mutex);
> return ret;
> }
> -
> diff --git a/drivers/staging/wfx/queue.c b/drivers/staging/wfx/queue.c
> index 729825230db2..a2745d1024c6 100644
> --- a/drivers/staging/wfx/queue.c
> +++ b/drivers/staging/wfx/queue.c
> @@ -207,7 +207,7 @@ bool wfx_tx_queues_has_cab(struct wfx_vif *wvif)
> {
> int i;
>
> - if (wvif->vif->type != NL80211_IFTYPE_AP)
> + if (wvif_to_vif(wvif)->type != NL80211_IFTYPE_AP)
> return false;
> for (i = 0; i < IEEE80211_NUM_ACS; ++i)
> /* Note: since only AP can have mcast frames in queue and only one vif can be AP,
> diff --git a/drivers/staging/wfx/scan.c b/drivers/staging/wfx/scan.c
> index 7f34f0d322f9..5c25fde3fc41 100644
> --- a/drivers/staging/wfx/scan.c
> +++ b/drivers/staging/wfx/scan.c
> @@ -25,7 +25,7 @@ static int update_probe_tmpl(struct wfx_vif *wvif, struct cfg80211_scan_request
> {
> struct sk_buff *skb;
>
> - skb = ieee80211_probereq_get(wvif->wdev->hw, wvif->vif->addr, NULL, 0, req->ie_len);
> + skb = ieee80211_probereq_get(wvif->wdev->hw, wvif_to_vif(wvif)->addr, NULL, 0, req->ie_len);

...and here,

> if (!skb)
> return -ENOMEM;
>
> @@ -75,8 +75,8 @@ static int send_scan_req(struct wfx_vif *wvif, struct cfg80211_scan_request *req
> } else {
> ret = wvif->scan_nb_chan_done;
> }
> - if (req->channels[start_idx]->max_power != wvif->vif->bss_conf.txpower)
> - wfx_hif_set_output_power(wvif, wvif->vif->bss_conf.txpower);
> + if (req->channels[start_idx]->max_power != wvif_to_vif(wvif)->bss_conf.txpower)
> + wfx_hif_set_output_power(wvif, wvif_to_vif(wvif)->bss_conf.txpower);


> wfx_tx_unlock(wvif->wdev);
> return ret;
> }
> diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c
> index 03025ef7f1be..b634c8e004db 100644
> --- a/drivers/staging/wfx/sta.c
> +++ b/drivers/staging/wfx/sta.c
> @@ -132,7 +132,7 @@ void wfx_configure_filter(struct ieee80211_hw *hw, unsigned int changed_flags,
> filter_bssid = true;
>
> /* In AP mode, chip can reply to probe request itself */
> - if (*total_flags & FIF_PROBE_REQ && wvif->vif->type == NL80211_IFTYPE_AP) {
> + if (*total_flags & FIF_PROBE_REQ && wvif_to_vif(wvif)->type == NL80211_IFTYPE_AP) {

and here,

> dev_dbg(wdev->dev, "do not forward probe request in AP mode\n");
> *total_flags &= ~FIF_PROBE_REQ;
> }
> @@ -153,18 +153,18 @@ static int wfx_get_ps_timeout(struct wfx_vif *wvif, bool *enable_ps)
> struct ieee80211_channel *chan0 = NULL, *chan1 = NULL;
> struct ieee80211_conf *conf = &wvif->wdev->hw->conf;
>
> - WARN(!wvif->vif->bss_conf.assoc && enable_ps,
> + WARN(!wvif_to_vif(wvif)->bss_conf.assoc && enable_ps,
> "enable_ps is reliable only if associated");
> if (wdev_to_wvif(wvif->wdev, 0))
> - chan0 = wdev_to_wvif(wvif->wdev, 0)->vif->bss_conf.chandef.chan;
> + chan0 = wvif_to_vif(wdev_to_wvif(wvif->wdev, 0))->bss_conf.chandef.chan;
> if (wdev_to_wvif(wvif->wdev, 1))
> - chan1 = wdev_to_wvif(wvif->wdev, 1)->vif->bss_conf.chandef.chan;
> - if (chan0 && chan1 && wvif->vif->type != NL80211_IFTYPE_AP) {
> + chan1 = wvif_to_vif(wdev_to_wvif(wvif->wdev, 1))->bss_conf.chandef.chan;
> + if (chan0 && chan1 && wvif_to_vif(wvif)->type != NL80211_IFTYPE_AP) {
> if (chan0->hw_value == chan1->hw_value) {
> /* It is useless to enable PS if channels are the same. */
> if (enable_ps)
> *enable_ps = false;
> - if (wvif->vif->bss_conf.assoc && wvif->vif->bss_conf.ps)
> + if (wvif_to_vif(wvif)->bss_conf.assoc && wvif_to_vif(wvif)->bss_conf.ps)
> dev_info(wvif->wdev->dev, "ignoring requested PS mode");
> return -1;
> }
> @@ -177,8 +177,8 @@ static int wfx_get_ps_timeout(struct wfx_vif *wvif, bool *enable_ps)
> return 30;
> }
> if (enable_ps)
> - *enable_ps = wvif->vif->bss_conf.ps;
> - if (wvif->vif->bss_conf.assoc && wvif->vif->bss_conf.ps)
> + *enable_ps = wvif_to_vif(wvif)->bss_conf.ps;
> + if (wvif_to_vif(wvif)->bss_conf.assoc && wvif_to_vif(wvif)->bss_conf.ps)
> return conf->dynamic_ps_timeout;
> else
> return -1;
> @@ -189,7 +189,7 @@ int wfx_update_pm(struct wfx_vif *wvif)
> int ps_timeout;
> bool ps;
>
> - if (!wvif->vif->bss_conf.assoc)
> + if (!wvif_to_vif(wvif)->bss_conf.assoc)
> return 0;
> ps_timeout = wfx_get_ps_timeout(wvif, &ps);
> if (!ps)
> @@ -215,7 +215,7 @@ int wfx_conf_tx(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
> mutex_lock(&wdev->conf_mutex);
> assign_bit(queue, &wvif->uapsd_mask, params->uapsd);
> wfx_hif_set_edca_queue_params(wvif, queue, params);
> - if (wvif->vif->type == NL80211_IFTYPE_STATION && old_uapsd != wvif->uapsd_mask) {
> + if (wvif_to_vif(wvif)->type == NL80211_IFTYPE_STATION && old_uapsd != wvif->uapsd_mask) {
> wfx_hif_set_uapsd_info(wvif, wvif->uapsd_mask);
> wfx_update_pm(wvif);
> }
> @@ -242,20 +242,20 @@ void wfx_event_report_rssi(struct wfx_vif *wvif, u8 raw_rcpi_rssi)
> int cqm_evt;
>
> rcpi_rssi = raw_rcpi_rssi / 2 - 110;
> - if (rcpi_rssi <= wvif->vif->bss_conf.cqm_rssi_thold)
> + if (rcpi_rssi <= wvif_to_vif(wvif)->bss_conf.cqm_rssi_thold)
> cqm_evt = NL80211_CQM_RSSI_THRESHOLD_EVENT_LOW;
> else
> cqm_evt = NL80211_CQM_RSSI_THRESHOLD_EVENT_HIGH;
> - ieee80211_cqm_rssi_notify(wvif->vif, cqm_evt, rcpi_rssi, GFP_KERNEL);
> + ieee80211_cqm_rssi_notify(wvif_to_vif(wvif), cqm_evt, rcpi_rssi, GFP_KERNEL);
> }
>
> static void wfx_beacon_loss_work(struct work_struct *work)
> {
> struct wfx_vif *wvif = container_of(to_delayed_work(work), struct wfx_vif,
> beacon_loss_work);
> - struct ieee80211_bss_conf *bss_conf = &wvif->vif->bss_conf;
> + struct ieee80211_bss_conf *bss_conf = &wvif_to_vif(wvif)->bss_conf;
>
> - ieee80211_beacon_loss(wvif->vif);
> + ieee80211_beacon_loss(wvif_to_vif(wvif));
> schedule_delayed_work(to_delayed_work(work), msecs_to_jiffies(bss_conf->beacon_int));
> }
>
> @@ -323,13 +323,13 @@ static int wfx_upload_ap_templates(struct wfx_vif *wvif)
> {
> struct sk_buff *skb;
>
> - skb = ieee80211_beacon_get(wvif->wdev->hw, wvif->vif);
> + skb = ieee80211_beacon_get(wvif->wdev->hw, wvif_to_vif(wvif));
> if (!skb)
> return -ENOMEM;
> wfx_hif_set_template_frame(wvif, skb, HIF_TMPLT_BCN, API_RATE_INDEX_B_1MBPS);
> dev_kfree_skb(skb);
>
> - skb = ieee80211_proberesp_get(wvif->wdev->hw, wvif->vif);
> + skb = ieee80211_proberesp_get(wvif->wdev->hw, wvif_to_vif(wvif));
> if (!skb)
> return -ENOMEM;
> wfx_hif_set_template_frame(wvif, skb, HIF_TMPLT_PRBRES, API_RATE_INDEX_B_1MBPS);
> @@ -339,7 +339,7 @@ static int wfx_upload_ap_templates(struct wfx_vif *wvif)
>
> static void wfx_set_mfp_ap(struct wfx_vif *wvif)
> {
> - struct sk_buff *skb = ieee80211_beacon_get(wvif->wdev->hw, wvif->vif);
> + struct sk_buff *skb = ieee80211_beacon_get(wvif->wdev->hw, wvif_to_vif(wvif));
> const int ieoffset = offsetof(struct ieee80211_mgmt, u.beacon.variable);
> const u16 *ptr = (u16 *)cfg80211_find_ie(WLAN_EID_RSN, skb->data + ieoffset,
> skb->len - ieoffset);
> @@ -389,7 +389,7 @@ void wfx_stop_ap(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
> static void wfx_join(struct wfx_vif *wvif)
> {
> int ret;
> - struct ieee80211_bss_conf *conf = &wvif->vif->bss_conf;
> + struct ieee80211_bss_conf *conf = &wvif_to_vif(wvif)->bss_conf;
> struct cfg80211_bss *bss = NULL;
> u8 ssid[IEEE80211_MAX_SSID_LEN];
> const u8 *ssid_ie = NULL;
> @@ -420,7 +420,7 @@ static void wfx_join(struct wfx_vif *wvif)
> wvif->join_in_progress = true;
> ret = wfx_hif_join(wvif, conf, wvif->channel, ssid, ssid_len);
> if (ret) {
> - ieee80211_connection_loss(wvif->vif);
> + ieee80211_connection_loss(wvif_to_vif(wvif));
> wfx_reset(wvif);
> } else {
> /* Due to beacon filtering it is possible that the AP's beacon is not known for the
> @@ -440,7 +440,7 @@ static void wfx_join_finalize(struct wfx_vif *wvif, struct ieee80211_bss_conf *i
>
> rcu_read_lock(); /* protect sta */
> if (info->bssid && !info->ibss_joined)
> - sta = ieee80211_find_sta(wvif->vif, info->bssid);
> + sta = ieee80211_find_sta(wvif_to_vif(wvif), info->bssid);
> if (sta && sta->ht_cap.ht_supported)
> ampdu_density = sta->ht_cap.ampdu_density;
> if (sta && sta->ht_cap.ht_supported &&
> @@ -565,7 +565,7 @@ static int wfx_update_tim(struct wfx_vif *wvif)
> u16 tim_offset, tim_length;
> u8 *tim_ptr;
>
> - skb = ieee80211_beacon_get_tim(wvif->wdev->hw, wvif->vif, &tim_offset, &tim_length);
> + skb = ieee80211_beacon_get_tim(wvif->wdev->hw, wvif_to_vif(wvif), &tim_offset, &tim_length);
> if (!skb)
> return -ENOENT;
> tim_ptr = skb->data + tim_offset;
> @@ -707,8 +707,6 @@ int wfx_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
> return -EOPNOTSUPP;
> }
>
> - /* FIXME: prefer use of container_of() to get vif */
> - wvif->vif = vif;
> wvif->wdev = wdev;
>
> wvif->link_id_map = 1; /* link-id 0 is reserved for multicast */
> @@ -767,7 +765,6 @@ void wfx_remove_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
>
> cancel_delayed_work_sync(&wvif->beacon_loss_work);
> wdev->vif[wvif->id] = NULL;
> - wvif->vif = NULL;
>
> mutex_unlock(&wdev->conf_mutex);
>

The rest looks good to me, except that, as Alison and Greg pointed out,
this isn't in staging anymore:
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?h=staging-next&id=4a5fb1bbcdf1cccae1f6b9c0277b3796b2a468ef

-- even if it was when we first discussed this change, and also,
as you already mentioned, you'll need to find somebody to test this on
actual hardware.

--
Stefano