USB host: Fix lockdep warning in AMD PLL quirk
commit9ab7927bb845cf2549110b19c212fe44a2bfbacb
authorJoerg Roedel <joerg.roedel@amd.com>
Wed, 13 Apr 2011 06:38:16 +0000 (13 08:38 +0200)
committerGreg Kroah-Hartman <gregkh@suse.de>
Wed, 13 Apr 2011 22:44:04 +0000 (13 15:44 -0700)
tree520fd86f8f3b78a27ee485291c9ca03026a4535d
parent16a2f970f3b4beb8d21009b2c45b9b5ab56bb621
USB host: Fix lockdep warning in AMD PLL quirk

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>
drivers/usb/host/pci-quirks.c