From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Date: Wed, 10 Sep 2014 18:49:26 +0000
Subject: q about ldc_bind after irq save
Message-Id: <20140910184926.GC14466@oracle.com>
List-Id: <sparclinux.vger.kernel.org>
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To: sparclinux@vger.kernel.org

This one (below) was flagged by lockdep. While it is a corner-case,
it does create lockdep noise, so I'm trying to figure out
the smallest fix for it:

 irq event stamp: 0
 hardirqs last  enabled at (0): [<          (null)>]           (null)
 hardirqs last disabled at (0): [<0000000000466c7c>] copy_process+0x33c/0xcc0
 softirqs last  enabled at (0): [<0000000000466c7c>] copy_process+0x33c/0xcc0
 softirqs last disabled at (0): [<          (null)>]           (null)
 Call Trace:
 [00000000004a0738] __might_sleep+0xf8/0x120
 [000000000058bea4] kmem_cache_alloc_trace+0x184/0x2c0
 [00000000004faf80] request_threaded_irq+0x80/0x160
 [000000000044f71c] ldc_bind+0x7c/0x220
 [0000000000452454] vio_port_up+0x54/0xe0
 [00000000101f6778] probe_disk+0x38/0x220 [sunvdc]
 [00000000101f6b8c] vdc_port_probe+0x22c/0x300 [sunvdc]
 [0000000000451a88] vio_device_probe+0x48/0x60
 [000000000074c56c] really_probe+0x6c/0x300
 [000000000074c83c] driver_probe_device+0x3c/0xa0
 [000000000074c92c] __driver_attach+0x8c/0xa0
 [000000000074a6ec] bus_for_each_dev+0x6c/0xa0
 [000000000074c1dc] driver_attach+0x1c/0x40
 [000000000074b0fc] bus_add_driver+0xbc/0x280

I think vio_port_up needs to do the irqsave before the ldc_bind
so that it can examine ldc_state() safely.

But is there a reason we can't move the request_irq from ldc_bind
and into ldc_alloc itself?  Or is there a simpler fix?

--Sowmini