linux-kernel - [PATCH net] tg3: prevent scheduling while atomic splat

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Message-Id: <f439051c3964c6bb5342e25fb5327e0cdeba001e.1521045132.git.jtoppins@redhat.com>
Date:   Wed, 14 Mar 2018 12:36:25 -0400
From:   Jonathan Toppins <jtoppins@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Andy Gospodarek <andy@...yhouse.net>,
        Siva Reddy Kallam <siva.kallam@...adcom.com>,
        Prashant Sreedharan <prashant@...adcom.com>,
        Michael Chan <mchan@...adcom.com>, linux-kernel@...r.kernel.org
Subject: [PATCH net] tg3: prevent scheduling while atomic splat

The problem was introduced in commit
506b0a395f26 ("[netdrv] tg3: APE heartbeat changes"). The bug occurs
because tp->lock spinlock is held which is obtained in tg3_start
by way of tg3_full_lock(), line 11571. The documentation for usleep_range()
specifically states it cannot be used inside a spinlock.

Fixes: 506b0a395f26 ("[netdrv] tg3: APE heartbeat changes")
Signed-off-by: Jonathan Toppins <jtoppins@...hat.com>
---

Notes:
    The thing I need reviewed from Broadcom is if the udelay should be 20
    instead of 10, due to any timing changes introduced by the offending
    patch.

 drivers/net/ethernet/broadcom/tg3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index c1841db1b500..f2593978ae75 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -820,7 +820,7 @@ static int tg3_ape_event_lock(struct tg3 *tp, u32 timeout_us)
 
 		tg3_ape_unlock(tp, TG3_APE_LOCK_MEM);
 
-		usleep_range(10, 20);
+		udelay(10);
 		timeout_us -= (timeout_us > 10) ? 10 : timeout_us;
 	}
 
-- 
2.13.6