[v3] perf: Convert mmap() related reference counts to refcount_t

[PATCH v3 01/15] perf: Remove redundant condition for AUX buffer size

Posted by Peter Zijlstra 1 month, 3 weeks ago

From: Thomas Gleixner <tglx@linutronix.de>

It is already checked whether the VMA size is the same as
nr_pages * PAGE_SIZE, so later checking both:

      aux_size == vma_size && aux_size == nr_pages * PAGE_SIZE

is redundant. Remove the vma_size check as nr_pages is what is actually
used in the allocation function. That prepares for splitting out the buffer
allocation into seperate functions, so that only nr_pages needs to be
handed in.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lkml.kernel.org/r/20250811070620.389961756@linutronix.de
---
 kernel/events/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7043,7 +7043,7 @@ static int perf_mmap(struct file *file,
 		if (rb_has_aux(rb) && rb->aux_pgoff != vma->vm_pgoff)
 			goto aux_unlock;
 
-		if (aux_size != vma_size || aux_size != nr_pages * PAGE_SIZE)
+		if (aux_size != nr_pages * PAGE_SIZE)
 			goto aux_unlock;
 
 		/* already mapped with a different size */

Re: [PATCH v3 01/15] perf: Remove redundant condition for AUX buffer size

Posted by Lorenzo Stoakes 1 month, 3 weeks ago

On Tue, Aug 12, 2025 at 12:38:59PM +0200, Peter Zijlstra wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> It is already checked whether the VMA size is the same as
> nr_pages * PAGE_SIZE, so later checking both:
>
>       aux_size == vma_size && aux_size == nr_pages * PAGE_SIZE
>
> is redundant. Remove the vma_size check as nr_pages is what is actually
> used in the allocation function. That prepares for splitting out the buffer
> allocation into seperate functions, so that only nr_pages needs to be

NIT: still get seperate -> separate typo there. Not a big deal obviously :)

> handed in.
>
> No functional change.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Link: https://lkml.kernel.org/r/20250811070620.389961756@linutronix.de
> ---
>  kernel/events/core.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7043,7 +7043,7 @@ static int perf_mmap(struct file *file,
>  		if (rb_has_aux(rb) && rb->aux_pgoff != vma->vm_pgoff)
>  			goto aux_unlock;
>
> -		if (aux_size != vma_size || aux_size != nr_pages * PAGE_SIZE)
> +		if (aux_size != nr_pages * PAGE_SIZE)
>  			goto aux_unlock;
>
>  		/* already mapped with a different size */
>
>

[tip: perf/core] perf: Remove redundant condition for AUX buffer size

Posted by tip-bot2 for Thomas Gleixner 1 month, 2 weeks ago

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     e8c4f6ee8eeed8e02800bed6afb9aa22fc3476a1
Gitweb:        https://git.kernel.org/tip/e8c4f6ee8eeed8e02800bed6afb9aa22fc3476a1
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Tue, 12 Aug 2025 12:38:59 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 15 Aug 2025 13:12:58 +02:00

perf: Remove redundant condition for AUX buffer size

It is already checked whether the VMA size is the same as
nr_pages * PAGE_SIZE, so later checking both:

      aux_size == vma_size && aux_size == nr_pages * PAGE_SIZE

is redundant. Remove the vma_size check as nr_pages is what is actually
used in the allocation function. That prepares for splitting out the buffer
allocation into separate functions, so that only nr_pages needs to be
handed in.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20250812104018.424519320@infradead.org
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8060c28..eea3a7d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7043,7 +7043,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 		if (rb_has_aux(rb) && rb->aux_pgoff != vma->vm_pgoff)
 			goto aux_unlock;
 
-		if (aux_size != vma_size || aux_size != nr_pages * PAGE_SIZE)
+		if (aux_size != nr_pages * PAGE_SIZE)
 			goto aux_unlock;
 
 		/* already mapped with a different size */