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SubjectRe: [PATCH] wfx: use container_of() to get vif
On Mon, May 02, 2022 at 02:10:07PM -0400, Jaehee wrote:
> On Wed, Apr 20, 2022 at 7:58 AM Kalle Valo <kvalo@kernel.org> wrote:
> >
> > Jaehee Park <jhpark1013@gmail.com> writes:
> >
> > > Currently, upon virtual interface creation, wfx_add_interface() stores
> > > a reference to the corresponding struct ieee80211_vif in private data,
> > > for later usage. This is not needed when using the container_of
> > > construct. This construct already has all the info it needs to retrieve
> > > the reference to the corresponding struct from the offset that is
> > > already available, inherent in container_of(), between its type and
> > > member inputs (struct ieee80211_vif and drv_priv, respectively).
> > > Remove vif (which was previously storing the reference to the struct
> > > ieee80211_vif) from the struct wfx_vif, define a function
> > > wvif_to_vif(wvif) for container_of(), and replace all wvif->vif with
> > > the newly defined container_of construct.
> > >
> > > Signed-off-by: Jaehee Park <jhpark1013@gmail.com>
> >
> > [...]
> >
> > > +static inline struct ieee80211_vif *wvif_to_vif(struct wfx_vif *wvif)
> > > +{
> > > + return container_of((void *)wvif, struct ieee80211_vif, drv_priv);
> > > +}
> >
> > Why the void pointer cast? Avoid casts as much possible.
> >
>
> Hi Kalle,
>
> Sorry for the delay in getting back to you about why the void pointer
> cast was used.
>
> In essence, I'm taking private data with a driver-specific pointer
> and that needs to be resolved back to a generic pointer.
>
> The private data (drv_priv) is declared as a generic u8 array in struct
> ieee80211_vif, but wvif is a more specific type.
>
> I wanted to also point to existing, reasonable examples such as:
> static void iwl_mvm_tcm_uapsd_nonagg_detected_wk(struct work_struct *wk)
> {
> struct iwl_mvm *mvm;
> struct iwl_mvm_vif *mvmvif;
> struct ieee80211_vif *vif;
>
> mvmvif = container_of(wk, struct iwl_mvm_vif,
> uapsd_nonagg_detected_wk.work);
> vif = container_of((void *)mvmvif, struct ieee80211_vif, drv_priv);
>
> in drivers/net/wireless$ less intel/iwlwifi/mvm/utils.c, which does the
> same thing.
>
> There are fifteen of them throughout:
> wireless-next/drivers/net/wireless$ grep -rn "container_of(.* ieee80211_vif"
> intel/iwlwifi/mvm/utils.c:794: vif = container_of((void *)mvmvif,
> struct ieee80211_vif, drv_priv);
> intel/iwlwifi/mvm/mac80211.c:1347: vif = container_of((void
> *)mvmvif, struct ieee80211_vif, drv_priv);
> mediatek/mt76/mt76x02_mmio.c:415: vif =
> container_of(priv, struct ieee80211_vif, drv_priv);
> mediatek/mt76/mt7615/mac.c:275: vif = container_of((void *)msta->vif,
> struct ieee80211_vif, drv_priv);
> mediatek/mt76/mt7915/mac.c:416: vif = container_of((void *)msta->vif,
> struct ieee80211_vif, drv_priv);
> mediatek/mt76/mt7915/mac.c:2327: vif =
> container_of((void *)msta->vif, struct ieee80211_vif, drv_priv);
> mediatek/mt76/mt7915/debugfs.c:1026: vif = container_of((void
> *)msta->vif, struct ieee80211_vif, drv_priv);
> mediatek/mt76/mt7921/mac.c:425: vif = container_of((void *)msta->vif,
> struct ieee80211_vif, drv_priv);
> ti/wlcore/wlcore_i.h:502: return container_of((void *)wlvif,
> struct ieee80211_vif, drv_priv);
> realtek/rtl818x/rtl8187/dev.c:1068: container_of((void
> *)vif_priv, struct ieee80211_vif, drv_priv);
> realtek/rtl818x/rtl8180/dev.c:1293: container_of((void
> *)vif_priv, struct ieee80211_vif, drv_priv);
> realtek/rtw88/main.h:2075: return container_of(p, struct
> ieee80211_vif, drv_priv);
> realtek/rtw89/core.h:3440: return container_of(p, struct
> ieee80211_vif, drv_priv);
> ath/carl9170/carl9170.h:641: return container_of((void *)priv,
> struct ieee80211_vif, drv_priv);
> ath/wcn36xx/wcn36xx.h:329: return container_of((void *) vif_priv,
> struct ieee80211_vif, drv_priv);
>

Sorry -- here's the last portion of the email without wrapping.

wireless-next/drivers/net/wireless$ grep -rn "container_of(.* ieee80211_vif"
intel/iwlwifi/mvm/utils.c:794: vif = container_of((void *)mvmvif, struct ieee80211_vif, drv_priv);
intel/iwlwifi/mvm/mac80211.c:1347: vif = container_of((void *)mvmvif, struct ieee80211_vif, drv_priv);
mediatek/mt76/mt76x02_mmio.c:415: vif = container_of(priv, struct ieee80211_vif, drv_priv);
mediatek/mt76/mt7615/mac.c:275: vif = container_of((void *)msta->vif, struct ieee80211_vif, drv_priv);
mediatek/mt76/mt7915/mac.c:416: vif = container_of((void *)msta->vif, struct ieee80211_vif, drv_priv);
mediatek/mt76/mt7915/mac.c:2327: vif = container_of((void *)msta->vif, struct ieee80211_vif, drv_priv);
mediatek/mt76/mt7915/debugfs.c:1026: vif = container_of((void *)msta->vif, struct ieee80211_vif, drv_priv);
mediatek/mt76/mt7921/mac.c:425: vif = container_of((void *)msta->vif, struct ieee80211_vif, drv_priv);
ti/wlcore/wlcore_i.h:502: return container_of((void *)wlvif, struct ieee80211_vif, drv_priv);
realtek/rtl818x/rtl8187/dev.c:1068: container_of((void *)vif_priv, struct ieee80211_vif, drv_priv);
realtek/rtl818x/rtl8180/dev.c:1293: container_of((void *)vif_priv, struct ieee80211_vif, drv_priv);
realtek/rtw88/main.h:2075: return container_of(p, struct ieee80211_vif, drv_priv);
realtek/rtw89/core.h:3440: return container_of(p, struct ieee80211_vif, drv_priv);
ath/carl9170/carl9170.h:641: return container_of((void *)priv, struct ieee80211_vif, drv_priv);
ath/wcn36xx/wcn36xx.h:329: return container_of((void *) vif_priv, struct ieee80211_vif, drv_priv);

> Thanks,
> Jaehee
>
>
> > --
> > https://patchwork.kernel.org/project/linux-wireless/list/
> >
> > https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

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