diff mbox series

[19/20] function_graph: Use for_each_set_bit() in __ftrace_return_to_handler()

Message ID 20240525023744.231570357@goodmis.org (mailing list archive)
State Superseded
Headers show
Series [01/20] function_graph: Convert ret_stack to a series of longs | expand

Commit Message

Steven Rostedt May 25, 2024, 2:37 a.m. UTC
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

Instead of iterating through the entire fgraph_array[] and seeing if one
of the bitmap bits are set to know to call the array's retfunc() function,
use for_each_set_bit() on the bitmap itself. This will only iterate for
the number of set bits.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/fgraph.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Comments

Masami Hiramatsu (Google) May 26, 2024, 11:58 p.m. UTC | #1
On Fri, 24 May 2024 22:37:11 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> 
> Instead of iterating through the entire fgraph_array[] and seeing if one
> of the bitmap bits are set to know to call the array's retfunc() function,
> use for_each_set_bit() on the bitmap itself. This will only iterate for
> the number of set bits.
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks,

> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
>  kernel/trace/fgraph.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 4d503b3e45ad..5e8e13ffcfb6 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -827,11 +827,10 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
>  #endif
>  
>  	bitmap = get_bitmap_bits(current, offset);
> -	for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
> +
> +	for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
>  		struct fgraph_ops *gops = fgraph_array[i];
>  
> -		if (!(bitmap & BIT(i)))
> -			continue;
>  		if (gops == &fgraph_stub)
>  			continue;
>  
> -- 
> 2.43.0
> 
>
Masami Hiramatsu (Google) May 27, 2024, 12:04 a.m. UTC | #2
On Fri, 24 May 2024 22:37:11 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> 
> Instead of iterating through the entire fgraph_array[] and seeing if one
> of the bitmap bits are set to know to call the array's retfunc() function,
> use for_each_set_bit() on the bitmap itself. This will only iterate for
> the number of set bits.
> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
>  kernel/trace/fgraph.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 4d503b3e45ad..5e8e13ffcfb6 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -827,11 +827,10 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
>  #endif
>  
>  	bitmap = get_bitmap_bits(current, offset);
> -	for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
> +
> +	for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
>  		struct fgraph_ops *gops = fgraph_array[i];
>  
> -		if (!(bitmap & BIT(i)))
> -			continue;
>  		if (gops == &fgraph_stub)

Ah, nit: maybe this is unlikely()?

Thank you,
Steven Rostedt May 27, 2024, 12:32 a.m. UTC | #3
On Mon, 27 May 2024 09:04:34 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> >  	bitmap = get_bitmap_bits(current, offset);
> > -	for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
> > +
> > +	for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
> >  		struct fgraph_ops *gops = fgraph_array[i];
> >  
> > -		if (!(bitmap & BIT(i)))
> > -			continue;
> >  		if (gops == &fgraph_stub)  
> 
> Ah, nit: maybe this is unlikely()?

Ah probably. I'll update it.

Thanks,

-- Steve
diff mbox series

Patch

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 4d503b3e45ad..5e8e13ffcfb6 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -827,11 +827,10 @@  static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
 #endif
 
 	bitmap = get_bitmap_bits(current, offset);
-	for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
+
+	for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
 		struct fgraph_ops *gops = fgraph_array[i];
 
-		if (!(bitmap & BIT(i)))
-			continue;
 		if (gops == &fgraph_stub)
 			continue;