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Message-ID: <d6999d74-45f6-413a-8881-90473b322dfa@linux.ibm.com>
Date: Fri, 14 Mar 2025 15:00:17 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: ajd@...ux.ibm.com
Cc: npiggin@...il.com, christophe.leroy@...roup.eu, mpe@...erman.id.au,
peterz@...radead.org, fbarrat@...ux.ibm.com, mahesh@...ux.ibm.com,
oohall@...il.com, hbathini@...ux.ibm.com, dhowells@...hat.com,
haren@...ux.ibm.com, linux-kernel@...r.kernel.org, maddy@...ux.ibm.com,
linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 5/6] powerpc: powenv: oxcl: use lock guard for mutex
On 3/14/25 11:15, Shrikanth Hegde wrote:
> 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
>
> Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
> ---
> 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.
> dev_dbg(&dev->dev, "%d PASIDs available for function\n",
> rc ? 0 : *count);
> return rc;
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