2022-03-14 21:33:18

by Suthikulpanit, Suravee

Subject: [PATCH] iommu/amd: Do not call sleep while holding spinlock

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 <[email protected]>
Fixes: dc6a709e5123 ("iommu/amd: Improve amd_iommu_v2_exit()")
Signed-off-by: Suravee Suthikulpanit <[email protected]>
---
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 490da41c3c71..5a6e4f87d875 100644
--- a/drivers/iommu/amd/iommu_v2.c
+++ b/drivers/iommu/amd/iommu_v2.c
@@ -947,6 +947,7 @@ 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;
@@ -966,11 +967,20 @@ 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);
}

--
2.17.1

2022-04-28 15:09:35

by Joerg Roedel

Subject: Re: [PATCH] iommu/amd: Do not call sleep while holding spinlock

On Sun, Mar 13, 2022 at 09:43:21PM -0500, Suravee Suthikulpanit wrote:
> 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 <[email protected]>
> Fixes: dc6a709e5123 ("iommu/amd: Improve amd_iommu_v2_exit()")
> Signed-off-by: Suravee Suthikulpanit <[email protected]>
> ---
> drivers/iommu/amd/iommu_v2.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)

Applied, thanks Suravee.