[PATCH 5.18 663/879] iommu/amd: Do not call sleep while holding spinlock

Greg Kroah-Hartman
2022-06-08T00:58:17Z

From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

[ Upstream commit 5edde870d3283edeaa27ab62ac4fac5ee8cae35a ]

Smatch static checker warns:
drivers/iommu/amd/iommu_v2.c:133 free_device_state()
warn: sleeping in atomic context

Fixes by storing the list of struct device_state in a temporary
list, and then free the memory after releasing the spinlock.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 9f968fc70d85 ("iommu/amd: Improve amd_iommu_v2_exit()")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20220314024321.37411-1-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iommu/amd/iommu_v2.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c
index e56b137ceabd..afb3efd565b7 100644
--- a/drivers/iommu/amd/iommu_v2.c
+++ b/drivers/iommu/amd/iommu_v2.c
@@ -956,6 +956,7 @@ static void __exit amd_iommu_v2_exit(void)
{
struct device_state *dev_state, *next;
unsigned long flags;
+ LIST_HEAD(freelist);

if (!amd_iommu_v2_supported())
return;
@@ -975,11 +976,20 @@ static void __exit amd_iommu_v2_exit(void)

put_device_state(dev_state);
list_del(&dev_state->list);
- free_device_state(dev_state);
+ list_add_tail(&dev_state->list, &freelist);
}

spin_unlock_irqrestore(&state_lock, flags);

+ /*
+ * Since free_device_state waits on the count to be zero,
+ * we need to free dev_state outside the spinlock.
+ */
+ list_for_each_entry_safe(dev_state, next, &freelist, list) {
+ list_del(&dev_state->list);
+ free_device_state(dev_state);
+ }
+
destroy_workqueue(iommu_wq);
}

--
2.35.1