a7ac783c33
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> |
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README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.