stable inclusion
from stable-5.10.24
commit 1e5ac057b05c4d41a0168d1b746e51ef30e86270
bugzilla: 51348

--------------------------------

[ Upstream commit 28a77185 ]

It is incorrect to always clear PRO when it's set w/o first checking
whether the overflow condition has been cleared. Current code assumes
that if an overflow condition occurs it must have been cleared by earlier
loop. However since the code runs in a threaded context, the overflow
condition could occur even after setting the head to the tail under some
extreme condition. To be sane, we should read both head/tail again when
seeing a pending PRO and only clear PRO after all pending PRs have been
handled.
Suggested-by: NKevin Tian <kevin.tian@intel.com>
Signed-off-by: NLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/linux-iommu/MWHPR11MB18862D2EA5BD432BF22D99A48CA09@MWHPR11MB1886.namprd11.prod.outlook.com/
Link: https://lore.kernel.org/r/20210126080730.2232859-2-baolu.lu@linux.intel.comSigned-off-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: N  Weilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>