On 05/31/2017 10:32 AM, Michael Büsch wrote:
On Wed, 31 May 2017 13:26:43 +0300
Kalle Valo <kvalo@xxxxxxxxxxxxxx> wrote:
Jia-Ju Bai <baijiaju1990@xxxxxxx> writes:
The driver may sleep under a spin lock, and the function call path is:
b43legacy_op_bss_info_changed (acquire the lock by spin_lock_irqsave)
b43legacy_synchronize_irq
synchronize_irq --> may sleep
To fix it, the lock is released before b43legacy_synchronize_irq, and the
lock is acquired again after this function.
Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxx>
---
drivers/net/wireless/broadcom/b43legacy/main.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/wireless/broadcom/b43legacy/main.c b/drivers/net/wireless/broadcom/b43legacy/main.c
index f1e3dad..31ead21 100644
--- a/drivers/net/wireless/broadcom/b43legacy/main.c
+++ b/drivers/net/wireless/broadcom/b43legacy/main.c
@@ -2859,7 +2859,9 @@ static void b43legacy_op_bss_info_changed(struct ieee80211_hw *hw,
b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0);
if (changed & BSS_CHANGED_BSSID) {
+ spin_unlock_irqrestore(&wl->irq_lock, flags);
b43legacy_synchronize_irq(dev);
+ spin_lock_irqsave(&wl->irq_lock, flags);
To me this looks like a fragile workaround and not a real fix. You can
easily add new race conditions with releasing the lock like this.
I think releasing the lock possibly is fine. It certainly is better than
sleeping with a lock held.
We disabled the device interrupts just before this line.
However I think the synchronize_irq should be outside of the
conditional right after the write to B43legacy_MMIO_GEN_IRQ_MASK. (So
two lines above)
I don't think it makes sense to only synchronize if BSS_CHANGED_BSSID
is set.
On the other hand b43 does not have this irq-disabling foobar anymore.
So somebody must have removed it. Maybe you can find the commit that
removed this stuff from b43 and port it to b43legacy?
So I would vote for moving the synchronize_irq up outside of the
conditional and put the unlock/lock sequence around it.
And as a second patch on top of that try to remove this stuff
altogether like b43 did.
The patch that removed it in b43 is
commit 36dbd9548e92268127b0c31b0e121e63e9207108
Author: Michael Buesch <mb@xxxxxxxxx>
Date: Fri Sep 4 22:51:29 2009 +0200
b43: Use a threaded IRQ handler
Use a threaded IRQ handler to allow locking the mutex and
sleeping while executing an interrupt.
This removes usage of the irq_lock spinlock, but introduces
a new hardirq_lock, which is _only_ used for the PCI/SSB lowlevel
hard-irq handler. Sleeping busses (SDIO) will use mutex instead.
Signed-off-by: Michael Buesch <mb@xxxxxxxxx>
Tested-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
I vaguely remember this patch. Although it is roughly a 1000-line fix, I will
try to port it to b43legacy. I still have an old BCM4306 PCMCIA card that I can
test in a PowerBook G4.
I agree with Michael that this is the way to go. Both of Jia-Ju's patches should
be rejected.
Larry
