[PATCH 4/6] powerpc: book3s: vas: use lock guard for mutex

From: Shrikanth Hegde
Date: Fri Mar 14 2025 - 01:47:15 EST


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@xxxxxxxxxxxxx/T/#u

There is also an example of using scoped_guard.

Signed-off-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
---
arch/powerpc/platforms/book3s/vas-api.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index 0b6365d85d11..eb1a97271afb 100644
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -425,7 +425,7 @@ static vm_fault_t vas_mmap_fault(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
}

- mutex_lock(&txwin->task_ref.mmap_mutex);
+ guard(mutex)(&txwin->task_ref.mmap_mutex);
/*
* The window may be inactive due to lost credit (Ex: core
* removal with DLPAR). If the window is active again when
@@ -437,11 +437,9 @@ static vm_fault_t vas_mmap_fault(struct vm_fault *vmf)
if (paste_addr) {
fault = vmf_insert_pfn(vma, vma->vm_start,
(paste_addr >> PAGE_SHIFT));
- mutex_unlock(&txwin->task_ref.mmap_mutex);
return fault;
}
}
- mutex_unlock(&txwin->task_ref.mmap_mutex);

/*
* Received this fault due to closing the actual window.
@@ -494,9 +492,8 @@ static void vas_mmap_close(struct vm_area_struct *vma)
return;
}

- mutex_lock(&txwin->task_ref.mmap_mutex);
- txwin->task_ref.vma = NULL;
- mutex_unlock(&txwin->task_ref.mmap_mutex);
+ scoped_guard(mutex, &txwin->task_ref.mmap_mutex)
+ txwin->task_ref.vma = NULL;
}

static const struct vm_operations_struct vas_vm_ops = {
@@ -543,18 +540,16 @@ static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
* close/open event and allows mmap() only when the window is
* active.
*/
- mutex_lock(&txwin->task_ref.mmap_mutex);
+ guard(mutex)(&txwin->task_ref.mmap_mutex);
if (txwin->status != VAS_WIN_ACTIVE) {
pr_err("Window is not active\n");
- rc = -EACCES;
- goto out;
+ return -EACCES;
}

paste_addr = cp_inst->coproc->vops->paste_addr(txwin);
if (!paste_addr) {
pr_err("Window paste address failed\n");
- rc = -EINVAL;
- goto out;
+ return -EINVAL;
}

pfn = paste_addr >> PAGE_SHIFT;
@@ -574,8 +569,6 @@ static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
txwin->task_ref.vma = vma;
vma->vm_ops = &vas_vm_ops;

-out:
- mutex_unlock(&txwin->task_ref.mmap_mutex);
return rc;
}

--
2.39.3