git: becb074fdefc - stable/14 - LinuxKPI: 802.11: adjust vif->bss_conf.chanctx_conf to rcu accessors

The branch stable/14 has been updated by bz:

URL: https://cgit.FreeBSD.org/src/commit/?id=becb074fdefc40cff3365746a1036843e16c09d6

commit becb074fdefc40cff3365746a1036843e16c09d6
Author:     Bjoern A. Zeeb <bz@FreeBSD.org>
AuthorDate: 2025-04-08 19:25:03 +0000
Commit:     Bjoern A. Zeeb <bz@FreeBSD.org>
CommitDate: 2025-04-18 14:36:01 +0000

    LinuxKPI: 802.11: adjust vif->bss_conf.chanctx_conf to rcu accessors
    
    Adjust the init and lkpi_sta_scan_to_auth() chanctx_conf accesses to
    use rcu functions as needed.
    linuxkpi_ieee80211_iterate_chan_contexts() which is
    ieee80211_iter_chan_contexts_atomic() needs further work to get rid
    of the vif locks by keeping all chanctx_conf on a list in lhw.
    This will be done in a follow-up commit.
    
    Sponsored by:   The FreeBSD Foundation
    PR:             280546
    Tested by:      Oleksandr Kryvulia (shuriku shurik.kiev.ua)
    Tested by:      Oleg Nauman (oleg.nauman gmail.com) [rtw88]
    Differential Revision: https://reviews.freebsd.org/D49734
    
    (cherry picked from commit 560708cbb0468bf1fd1834f4894a1326e88ff10e)
---
 sys/compat/linuxkpi/common/src/linux_80211.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/sys/compat/linuxkpi/common/src/linux_80211.c b/sys/compat/linuxkpi/common/src/linux_80211.c
index 1eff90a1d93e..bd1e60928144 100644
--- a/sys/compat/linuxkpi/common/src/linux_80211.c
+++ b/sys/compat/linuxkpi/common/src/linux_80211.c
@@ -1844,8 +1844,9 @@ lkpi_sta_scan_to_auth(struct ieee80211vap *vap, enum ieee80211_state nstate, int
 	LKPI_80211_LHW_LOCK(lhw);
 
 	/* Add chanctx (or if exists, change it). */
-	if (vif->bss_conf.chanctx_conf != NULL) {
-		chanctx_conf = vif->bss_conf.chanctx_conf;
+	chanctx_conf = rcu_dereference_protected(vif->bss_conf.chanctx_conf,
+	    lockdep_is_held(&hw->wiphy->mtx));
+	if (chanctx_conf != NULL) {
 		lchanctx = CHANCTX_CONF_TO_LCHANCTX(chanctx_conf);
 		IMPROVE("diff changes for changed, working on live copy, rcu");
 	} else {
@@ -1920,7 +1921,7 @@ lkpi_sta_scan_to_auth(struct ieee80211vap *vap, enum ieee80211_state nstate, int
 	bss_changed |= lkpi_update_dtim_tsf(vif, ni, vap, __func__, __LINE__);
 
 	error = 0;
-	if (vif->bss_conf.chanctx_conf != NULL) {
+	if (vif->bss_conf.chanctx_conf == chanctx_conf) {
 		changed = IEEE80211_CHANCTX_CHANGE_MIN_WIDTH;
 		changed |= IEEE80211_CHANCTX_CHANGE_RADAR;
 		changed |= IEEE80211_CHANCTX_CHANGE_RX_CHAINS;
@@ -1941,7 +1942,7 @@ lkpi_sta_scan_to_auth(struct ieee80211vap *vap, enum ieee80211_state nstate, int
 			goto out;
 		}
 
-		vif->bss_conf.chanctx_conf = chanctx_conf;
+		rcu_assign_pointer(vif->bss_conf.chanctx_conf, chanctx_conf);
 
 		/* Assign vif chanctx. */
 		if (error == 0)
@@ -1953,7 +1954,7 @@ lkpi_sta_scan_to_auth(struct ieee80211vap *vap, enum ieee80211_state nstate, int
 			ic_printf(vap->iv_ic, "%s:%d: mo_assign_vif_chanctx "
 			    "failed: %d\n", __func__, __LINE__, error);
 			lkpi_80211_mo_remove_chanctx(hw, chanctx_conf);
-			vif->bss_conf.chanctx_conf = NULL;
+			rcu_assign_pointer(vif->bss_conf.chanctx_conf, NULL);
 			lchanctx = CHANCTX_CONF_TO_LCHANCTX(chanctx_conf);
 			free(lchanctx, M_LKPI80211);
 			goto out;
@@ -3480,7 +3481,7 @@ lkpi_ic_vap_create(struct ieee80211com *ic, const char name[IFNAMSIZ],
 
 	/* XXX-BZ hardcoded for now! */
 #if 1
-	vif->bss_conf.chanctx_conf = NULL;
+	RCU_INIT_POINTER(vif->bss_conf.chanctx_conf, NULL);
 	vif->bss_conf.vif = vif;
 	/* vap->iv_myaddr is not set until net80211::vap_setup or vap_attach. */
 	IEEE80211_ADDR_COPY(vif->bss_conf.addr, mac);
@@ -5981,7 +5982,7 @@ linuxkpi_ieee80211_iterate_chan_contexts(struct ieee80211_hw *hw,
 	TAILQ_FOREACH(lvif, &lhw->lvif_head, lvif_entry) {
 
 		vif = LVIF_TO_VIF(lvif);
-		if (vif->bss_conf.chanctx_conf == NULL)
+		if (vif->bss_conf.chanctx_conf == NULL)			/* XXX-BZ; FIXME see IMPROVE above. */
 			continue;
 
 		lchanctx = CHANCTX_CONF_TO_LCHANCTX(vif->bss_conf.chanctx_conf);