From: Duoming Zhou <duoming@zju.edu.cn>
To: linux-kernel@vger.kernel.org
Cc: linux-staging@lists.linux.dev, alexander.deucher@amd.com,
davem@davemloft.net, gregkh@linuxfoundation.org,
Duoming Zhou <duoming@zju.edu.cn>
Subject: [PATCH V2 06/11] drivers: staging: rtl8192bs: Fix deadlock in rtw_joinbss_event_prehandle()
Date: Sat, 9 Apr 2022 14:49:53 +0800 [thread overview]
Message-ID: <20220409064953.67420-1-duoming@zju.edu.cn> (raw)
There is a deadlock in rtw_joinbss_event_prehandle(), which is shown
below:
(Thread 1) | (Thread 2)
| _set_timer()
rtw_joinbss_event_prehandle()| mod_timer()
spin_lock_bh() //(1) | (wait a time)
... | _rtw_join_timeout_handler()
del_timer_sync() | spin_lock_bh() //(2)
(wait timer to stop) | ...
We hold pmlmepriv->lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need pmlmepriv->lock in position (2) of thread 2.
As a result, rtw_joinbss_event_prehandle() will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_bh(), which could let timer handler to obtain
the needed lock. What`s more, we change spin_lock_bh() to
spin_lock_irq() in _rtw_join_timeout_handler() in order to
prevent deadlock.
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
Changes in V2:
- Change spin_lock_bh() to spin_lock_irq() in
_rtw_join_timeout_handler().
drivers/staging/rtl8723bs/core/rtw_mlme.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index 62f140985e3..24d6af886f7 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
@@ -1240,8 +1240,10 @@ void rtw_joinbss_event_prehandle(struct adapter *adapter, u8 *pbuf)
spin_unlock_bh(&pmlmepriv->scanned_queue.lock);
+ spin_unlock_bh(&pmlmepriv->lock);
/* s5. Cancel assoc_timer */
del_timer_sync(&pmlmepriv->assoc_timer);
+ spin_lock_bh(&pmlmepriv->lock);
} else {
spin_unlock_bh(&(pmlmepriv->scanned_queue.lock));
}
@@ -1547,7 +1549,7 @@ void _rtw_join_timeout_handler(struct timer_list *t)
if (adapter->bDriverStopped || adapter->bSurpriseRemoved)
return;
- spin_lock_bh(&pmlmepriv->lock);
+ spin_lock_irq(&pmlmepriv->lock);
if (rtw_to_roam(adapter) > 0) { /* join timeout caused by roaming */
while (1) {
@@ -1575,7 +1577,7 @@ void _rtw_join_timeout_handler(struct timer_list *t)
}
- spin_unlock_bh(&pmlmepriv->lock);
+ spin_unlock_irq(&pmlmepriv->lock);
}
/*
--
2.17.1
reply other threads:[~2022-04-09 6:50 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220409064953.67420-1-duoming@zju.edu.cn \
--to=duoming@zju.edu.cn \
--cc=alexander.deucher@amd.com \
--cc=davem@davemloft.net \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-staging@lists.linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).