brcmsmac: fix tx queue flush infinite loop

commit f96b08a7e6f69c0f0a576554df3df5b1b519c479 upstream.

This patch workaround live deadlock problem caused by infinite loop
in brcms_c_wait_for_tx_completion(). I do not consider the patch as
the proper fix, which should fix the real reason of tx queue flush
failure, but patch helps with system lockup.

Reference:
https://bugzilla.kernel.org/show_bug.cgi?id=42576

Reported-and-tested-by: Patrick <ragamuffin@datacomm.ch>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/wireless/brcm80211/brcmsmac/main.c b/drivers/net/wireless/brcm80211/brcmsmac/main.c
index 510e9bb..453f58e 100644 (file)
--- a/drivers/net/wireless/brcm80211/brcmsmac/main.c
+++ b/drivers/net/wireless/brcm80211/brcmsmac/main.c
@@ -8217,13 +8217,21 @@ int brcms_c_get_curband(struct brcms_c_info *wlc)
 
 void brcms_c_wait_for_tx_completion(struct brcms_c_info *wlc, bool drop)
 {
+       int timeout = 20;
+
        /* flush packet queue when requested */
        if (drop)
                brcmu_pktq_flush(&wlc->pkt_queue->q, false, NULL, NULL);
 
        /* wait for queue and DMA fifos to run dry */
-       while (!pktq_empty(&wlc->pkt_queue->q) || brcms_txpktpendtot(wlc) > 0)
+       while (!pktq_empty(&wlc->pkt_queue->q) || brcms_txpktpendtot(wlc) > 0) {
                brcms_msleep(wlc->wl, 1);
+
+               if (--timeout == 0)
+                       break;
+       }
+
+       WARN_ON_ONCE(timeout == 0);
 }
 
 void brcms_c_set_beacon_listen_interval(struct brcms_c_info *wlc, u8 interval)