linux-kernel - [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode

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Message-Id: <1496226547-5921-1-git-send-email-baijiaju1990@163.com>
Date:   Wed, 31 May 2017 18:29:07 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     Larry.Finger@...inger.net, kvalo@...eaurora.org
Cc:     linux-wireless@...r.kernel.org, b43-dev@...ts.infradead.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@....com>
Subject: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_attr_interfmode_store

The driver may sleep under a spin lock, and the function call path is:
b43legacy_attr_interfmode_store (acquire the lock by spin_lock_irqsave)
  b43legacy_radio_set_interference_mitigation
    b43legacy_radio_interference_mitigation_disable
      b43legacy_calc_nrssi_slope
        b43legacy_synth_pu_workaround
          might_sleep and msleep --> may sleep

Fixing it may be complex, and a possible way is to remove 
spin_lock_irqsave and spin_lock_irqrestore in 
b43legacy_attr_interfmode_store, and the code has been protected by
mutex_lock and mutex_unlock.

Signed-off-by: Jia-Ju Bai <baijiaju1990@....com>
---
 drivers/net/wireless/broadcom/b43legacy/sysfs.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43legacy/sysfs.c b/drivers/net/wireless/broadcom/b43legacy/sysfs.c
index 2a1da15..9ede143 100644
--- a/drivers/net/wireless/broadcom/b43legacy/sysfs.c
+++ b/drivers/net/wireless/broadcom/b43legacy/sysfs.c
@@ -137,14 +137,12 @@ static ssize_t b43legacy_attr_interfmode_store(struct device *dev,
 	}
 
 	mutex_lock(&wldev->wl->mutex);
-	spin_lock_irqsave(&wldev->wl->irq_lock, flags);
 
 	err = b43legacy_radio_set_interference_mitigation(wldev, mode);
 	if (err)
 		b43legacyerr(wldev->wl, "Interference Mitigation not "
 		       "supported by device\n");
 	mmiowb();
-	spin_unlock_irqrestore(&wldev->wl->irq_lock, flags);
 	mutex_unlock(&wldev->wl->mutex);
 
 	return err ? err : count;
-- 
1.7.9.5