[PATCH 5.15 024/279] staging: rtl8723bs: remove a second possible deadlock

Greg Kroah-Hartman
2021-11-24T13:46:04Z

From: Hans de Goede <hdegoede@redhat.com>

[ Upstream commit a7ac783c338bafc04d3259600646350dba989043 ]

Lockdep complains about rtw_free_assoc_resources() taking the sta_hash_lock
followed by it calling rtw_free_stainfo() which takes xmitpriv->lock.
While the rtl8723bs_xmit_thread takes the sta_hash_lock while already
holding the xmitpriv->lock:

[ 103.849756] ======================================================
[ 103.849761] WARNING: possible circular locking dependency detected
[ 103.849767] 5.15.0-rc1+ #470 Tainted: G C E
[ 103.849773] ------------------------------------------------------
[ 103.849776] wpa_supplicant/695 is trying to acquire lock:
[ 103.849781] ffffa5d0c0562b00 (&pxmitpriv->lock){+.-.}-{2:2}, at: rtw_free_stainfo+0x8a/0x510 [r8723bs]
[ 103.849840]
but task is already holding lock:
[ 103.849843] ffffa5d0c05636a8 (&pstapriv->sta_hash_lock){+.-.}-{2:2}, at: rtw_free_assoc_resources+0x48/0x110 [r8723bs]
[ 103.849881]
which lock already depends on the new lock.

[ 103.849884]
the existing dependency chain (in reverse order) is:
[ 103.849887]
-> #1 (&pstapriv->sta_hash_lock){+.-.}-{2:2}:
[ 103.849898] _raw_spin_lock_bh+0x34/0x40
[ 103.849913] rtw_get_stainfo+0x93/0x110 [r8723bs]
[ 103.849948] rtw_make_wlanhdr+0x14a/0x270 [r8723bs]
[ 103.849983] rtw_xmitframe_coalesce+0x5c/0x6c0 [r8723bs]
[ 103.850019] rtl8723bs_xmit_thread+0x4ac/0x620 [r8723bs]
[ 103.850050] kthread+0x143/0x160
[ 103.850058] ret_from_fork+0x22/0x30
[ 103.850067]
-> #0 (&pxmitpriv->lock){+.-.}-{2:2}:
[ 103.850077] __lock_acquire+0x1158/0x1de0
[ 103.850084] lock_acquire+0xb5/0x2b0
[ 103.850090] _raw_spin_lock_bh+0x34/0x40
[ 103.850095] rtw_free_stainfo+0x8a/0x510 [r8723bs]
[ 103.850130] rtw_free_assoc_resources+0x53/0x110 [r8723bs]
[ 103.850159] PHY_IQCalibrate_8723B+0x122b/0x36a0 [r8723bs]
[ 103.850189] cfg80211_disconnect+0x173/0x320 [cfg80211]
[ 103.850331] nl80211_disconnect+0x6e/0xb0 [cfg80211]
[ 103.850422] genl_family_rcv_msg_doit+0xcd/0x110
[ 103.850430] genl_rcv_msg+0xce/0x1c0
[ 103.850435] netlink_rcv_skb+0x50/0xf0
[ 103.850441] genl_rcv+0x24/0x40
[ 103.850446] netlink_unicast+0x16d/0x230
[ 103.850452] netlink_sendmsg+0x22b/0x450
[ 103.850457] sock_sendmsg+0x5e/0x60
[ 103.850465] ____sys_sendmsg+0x22f/0x270
[ 103.850472] ___sys_sendmsg+0x81/0xc0
[ 103.850479] __sys_sendmsg+0x49/0x80
[ 103.850485] do_syscall_64+0x3b/0x90
[ 103.850493] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 103.850500]
other info that might help us debug this:

[ 103.850504] Possible unsafe locking scenario:

[ 103.850507] CPU0 CPU1
[ 103.850510] ---- ----
[ 103.850512] lock(&pstapriv->sta_hash_lock);
[ 103.850518] lock(&pxmitpriv->lock);
[ 103.850524] lock(&pstapriv->sta_hash_lock);
[ 103.850530] lock(&pxmitpriv->lock);
[ 103.850535]
*** DEADLOCK ***

Push the taking of sta_hash_lock down into rtw_free_stainfo(),
where the critical section is, this allows taking the lock after
rtw_free_stainfo() has released pxmitpriv->lock.

This requires changing rtw_free_all_stainfo() so that it does its freeing
in 2 steps, first moving all stainfo-s to free to a local list while
holding the sta_hash_lock and then walking that list to call
rtw_free_stainfo() on them without holding the sta_hash_lock.

Pushing the taking of sta_hash_lock down into rtw_free_stainfo(),
also fixes a whole bunch of callers of rtw_free_stainfo() which
were not holding that lock even though they should.

Note that this also fixes the deadlock from the "remove possible
deadlock when disconnect" patch in a different way. But the
changes from that patch offer a nice locking cleanup regardless.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210920145502.155454-2-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/staging/rtl8723bs/core/rtw_mlme.c | 5 -----
drivers/staging/rtl8723bs/core/rtw_mlme_ext.c | 4 ----
drivers/staging/rtl8723bs/core/rtw_sta_mgt.c | 11 +++++++++--
drivers/staging/rtl8723bs/os_dep/ioctl_linux.c | 2 --
4 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index ab6a24d70cc96..1f49c49e10b45 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
@@ -897,7 +897,6 @@ void rtw_free_assoc_resources(struct adapter *adapter, int lock_scanned_queue)
{
struct mlme_priv *pmlmepriv = &adapter->mlmepriv;
struct wlan_network *tgt_network = &pmlmepriv->cur_network;
- struct sta_priv *pstapriv = &adapter->stapriv;
struct dvobj_priv *psdpriv = adapter->dvobj;
struct debug_priv *pdbgpriv = &psdpriv->drv_dbg;

@@ -905,11 +904,7 @@ void rtw_free_assoc_resources(struct adapter *adapter, int lock_scanned_queue)
struct sta_info *psta;

psta = rtw_get_stainfo(&adapter->stapriv, tgt_network->network.mac_address);
- spin_lock_bh(&(pstapriv->sta_hash_lock));
rtw_free_stainfo(adapter, psta);
-
- spin_unlock_bh(&(pstapriv->sta_hash_lock));
-
}

if (check_fwstate(pmlmepriv, WIFI_ADHOC_STATE|WIFI_ADHOC_MASTER_STATE|WIFI_AP_STATE)) {
diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
index a1ae16ec69eb6..ad9c237054c4b 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
@@ -1489,9 +1489,7 @@ unsigned int OnDeAuth(struct adapter *padapter, union recv_frame *precv_frame)
struct sta_info *psta;
struct sta_priv *pstapriv = &padapter->stapriv;

- /* spin_lock_bh(&(pstapriv->sta_hash_lock)); */
/* rtw_free_stainfo(padapter, psta); */
- /* spin_unlock_bh(&(pstapriv->sta_hash_lock)); */

netdev_dbg(padapter->pnetdev,
"ap recv deauth reason code(%d) sta:%pM\n", reason,
@@ -1565,9 +1563,7 @@ unsigned int OnDisassoc(struct adapter *padapter, union recv_frame *precv_frame)
struct sta_info *psta;
struct sta_priv *pstapriv = &padapter->stapriv;

- /* spin_lock_bh(&(pstapriv->sta_hash_lock)); */
/* rtw_free_stainfo(padapter, psta); */
- /* spin_unlock_bh(&(pstapriv->sta_hash_lock)); */

netdev_dbg(padapter->pnetdev,
"ap recv disassoc reason code(%d) sta:%pM\n",
diff --git a/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c b/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
index c23d0c833ecf8..3d269842677dd 100644
--- a/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
+++ b/drivers/staging/rtl8723bs/core/rtw_sta_mgt.c
@@ -263,7 +263,6 @@ exit:
return psta;
}

-/* using pstapriv->sta_hash_lock to protect */
u32 rtw_free_stainfo(struct adapter *padapter, struct sta_info *psta)
{
int i;
@@ -334,8 +333,10 @@ u32 rtw_free_stainfo(struct adapter *padapter, struct sta_info *psta)

spin_unlock_bh(&pxmitpriv->lock);

+ spin_lock_bh(&pstapriv->sta_hash_lock);
list_del_init(&psta->hash_list);
pstapriv->asoc_sta_count--;
+ spin_unlock_bh(&pstapriv->sta_hash_lock);

/* re-init sta_info; 20061114 will be init in alloc_stainfo */
/* _rtw_init_sta_xmit_priv(&psta->sta_xmitpriv); */
@@ -430,6 +431,7 @@ void rtw_free_all_stainfo(struct adapter *padapter)
struct sta_info *psta = NULL;
struct sta_priv *pstapriv = &padapter->stapriv;
struct sta_info *pbcmc_stainfo = rtw_get_bcmc_stainfo(padapter);
+ LIST_HEAD(stainfo_free_list);

if (pstapriv->asoc_sta_count == 1)
return;
@@ -442,11 +444,16 @@ void rtw_free_all_stainfo(struct adapter *padapter)
psta = list_entry(plist, struct sta_info, hash_list);

if (pbcmc_stainfo != psta)
- rtw_free_stainfo(padapter, psta);
+ list_move(&psta->hash_list, &stainfo_free_list);
}
}

spin_unlock_bh(&pstapriv->sta_hash_lock);
+
+ list_for_each_safe(plist, tmp, &stainfo_free_list) {
+ psta = list_entry(plist, struct sta_info, hash_list);
+ rtw_free_stainfo(padapter, psta);
+ }
}

/* any station allocated can be searched by hash list */
diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
index 9d4a233a861e3..295121c268bd4 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
@@ -835,9 +835,7 @@ static int rtw_add_sta(struct net_device *dev, struct ieee_param *param)
psta = rtw_get_stainfo(pstapriv, param->sta_addr);
if (psta)
{
- spin_lock_bh(&(pstapriv->sta_hash_lock));
rtw_free_stainfo(padapter, psta);
- spin_unlock_bh(&(pstapriv->sta_hash_lock));

psta = NULL;
}
--
2.33.0