tree 16f6096b5ab13a42c7119e3d5f9c0b21817eacaf
parent 25cbff1660d3f4c059a178a1e5b851be6d70c5e8
author Jiri Slaby <jirislaby@gmail.com> 1276528652 +0200
committer David Woodhouse <David.Woodhouse@intel.com> 1276595446 +0100

intel-iommu: Fix double lock in get_domain_for_dev()

stanse found the following double lock.

In get_domain_for_dev:
  spin_lock_irqsave(&device_domain_lock, flags);
  domain_exit(domain);
    domain_remove_dev_info(domain);
      spin_lock_irqsave(&device_domain_lock, flags);
      spin_unlock_irqrestore(&device_domain_lock, flags);
  spin_unlock_irqrestore(&device_domain_lock, flags);

This happens when the domain is created by another CPU at the same time 
as this function is creating one, and the other CPU wins the race to 
attach it to the device in question, so we have to destroy our own 
newly-created one.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>