Booting latest kernel on my test machine produces a lockdep
warning from the usb_amd_find_chipset_info() function:
WARNING: at /data/lemmy/linux.trees.git/kernel/lockdep.c:2465 lockdep_trace_alloc+0x95/0xc2()
Hardware name: Snook
Modules linked in:
Pid: 959, comm: work_for_cpu Not tainted 2.6.39-rc2+ #22
Call Trace:
[<ffffffff8103c0d4>] warn_slowpath_common+0x80/0x98
[<ffffffff812387e6>] ? T.492+0x24/0x26
[<ffffffff8103c101>] warn_slowpath_null+0x15/0x17
[<ffffffff81068667>] lockdep_trace_alloc+0x95/0xc2
[<ffffffff810ed9ac>] slab_pre_alloc_hook+0x18/0x3b
[<ffffffff810ef227>] kmem_cache_alloc_trace+0x25/0xba
[<ffffffff812387e6>] T.492+0x24/0x26
[<ffffffff81238816>] pci_get_subsys+0x2e/0x73
[<ffffffff8123886c>] pci_get_device+0x11/0x13
[<ffffffff814082a9>] usb_amd_find_chipset_info+0x3f/0x18a
...
It turns out that this function calls pci_get_device under a spin_lock
with irqs disabled, but the pci_get_device function is only allowed in
preemptible context.
This patch fixes the warning by making all data-structure
modifications on temporal storage and commiting this back
into the visible structure at the end. While at it, this
patch also moves the pci_dev_put calls out of the spinlocks
because this function might sleep too.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
9ab7927bb8