On 3/14/25 15:00, Shrikanth Hegde wrote:

On 3/14/25 11:15, Shrikanth Hegde wrote:

quoted

use guard(mutex) for scope based resource management of mutex.
This would make the code simpler and easier to maintain.

More details on lock guards can be found at
https://lore.kernel.org/all/20230612093537.614161713@infradead.org/T/#u (local)

Signed-off-by: Shrikanth Hegde <redacted>
---
  arch/powerpc/platforms/powernv/ocxl.c | 12 +++---------
  1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/ 

platforms/powernv/ocxl.c
index 64a9c7125c29..f8139948348e 100644

--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c

@@ -172,12 +172,11 @@ static void pnv_ocxl_fixup_actag(struct pci_dev 

*dev)
      if (phb->type != PNV_PHB_NPU_OCAPI)
          return;
-    mutex_lock(&links_list_lock);
+    guard(mutex)(&links_list_lock);
      link = find_link(dev);
      if (!link) {
          dev_warn(&dev->dev, "couldn't update actag information\n");
-        mutex_unlock(&links_list_lock);
          return;
      }

@@ -206,7 +205,6 @@ static void pnv_ocxl_fixup_actag(struct pci_dev *dev)

      dev_dbg(&dev->dev, "total actags for function: %d\n",
          link->fn_desired_actags[PCI_FUNC(dev->devfn)]);
-    mutex_unlock(&links_list_lock);
  }
  DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, pnv_ocxl_fixup_actag);

@@ -253,12 +251,11 @@ int pnv_ocxl_get_actag(struct pci_dev *dev, u16 

*base, u16 *enabled,
  {
      struct npu_link *link;
-    mutex_lock(&links_list_lock);
+    guard(mutex)(&links_list_lock);
      link = find_link(dev);
      if (!link) {
          dev_err(&dev->dev, "actag information not found\n");
-        mutex_unlock(&links_list_lock);
          return -ENODEV;
      }
      /*

@@ -274,7 +271,6 @@ int pnv_ocxl_get_actag(struct pci_dev *dev, u16 

*base, u16 *enabled,
      *enabled   = link->fn_actags[PCI_FUNC(dev->devfn)].count;
      *supported = link->fn_desired_actags[PCI_FUNC(dev->devfn)];
-    mutex_unlock(&links_list_lock);
      return 0;
  }
  EXPORT_SYMBOL_GPL(pnv_ocxl_get_actag);

@@ -293,12 +289,11 @@ int pnv_ocxl_get_pasid_count(struct pci_dev 

*dev, int *count)
       *
       * We only support one AFU-carrying function for now.
       */
-    mutex_lock(&links_list_lock);
+    guard(mutex)(&links_list_lock);
      link = find_link(dev);
      if (!link) {
          dev_err(&dev->dev, "actag information not found\n");
-        mutex_unlock(&links_list_lock);
          return -ENODEV;
      }

@@ -309,7 +304,6 @@ int pnv_ocxl_get_pasid_count(struct pci_dev *dev, 

int *count)
              break;
          }
-    mutex_unlock(&links_list_lock);

Hi. Andrew,

After this change below dev_dbg will be called with mutex held still. Is 
that a concern? I don't see the mutex being used in that path.

Since using scoped_guard cause more code churn here, I would prefer not 
use it.

I see current code in pnv_ocxl_fixup_actag calls dev_dbg with mutex 
held. So likely not a concern of using just guard in 
pnv_ocxl_get_pasid_count as well.

Assuming that, let me send out v2 with corrected commit subject. :w

quoted

      dev_dbg(&dev->dev, "%d PASIDs available for function\n",
          rc ? 0 : *count);
      return rc;