linux-kernel - [PATCH v4 2/2] ftrace: Introduce and use ENTRIES_PER_PAGE

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Message-ID: <20260113152243.3557219-2-linux@roeck-us.net>
Date: Tue, 13 Jan 2026 07:22:43 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH v4 2/2] ftrace: Introduce and use ENTRIES_PER_PAGE_GROUP macro

ENTRIES_PER_PAGE_GROUP() returns the number of dyn_ftrace entries in a page
group, identified by its order.

No functional change.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
v4: New patch, optional. Squash, drop, or apply as separate patch.

 kernel/trace/ftrace.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index aa758efc3731..df4ce244202e 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1148,6 +1148,7 @@ struct ftrace_page {
 };
 
 #define ENTRY_SIZE sizeof(struct dyn_ftrace)
+#define ENTRIES_PER_PAGE_GROUP(order) ((PAGE_SIZE << (order)) / ENTRY_SIZE)
 
 static struct ftrace_page	*ftrace_pages_start;
 static struct ftrace_page	*ftrace_pages;
@@ -3862,7 +3863,7 @@ static int ftrace_allocate_records(struct ftrace_page *pg, int count,
 	*num_pages += 1 << order;
 	ftrace_number_of_groups++;
 
-	cnt = (PAGE_SIZE << order) / ENTRY_SIZE;
+	cnt = ENTRIES_PER_PAGE_GROUP(order);
 	pg->order = order;
 
 	if (cnt > count)
@@ -7309,7 +7310,7 @@ static int ftrace_process_locs(struct module *mod,
 		long skip;
 
 		/* Count the number of entries unused and compare it to skipped. */
-		pg_remaining = (PAGE_SIZE << pg->order) / ENTRY_SIZE - pg->index;
+		pg_remaining = ENTRIES_PER_PAGE_GROUP(pg->order) - pg->index;
 
 		if (!WARN(skipped < pg_remaining, "Extra allocated pages for ftrace")) {
 
@@ -7317,7 +7318,7 @@ static int ftrace_process_locs(struct module *mod,
 
 			for (pg = pg_unuse; pg && skip > 0; pg = pg->next) {
 				remaining += 1 << pg->order;
-				skip -= (PAGE_SIZE << pg->order) / ENTRY_SIZE;
+				skip -= ENTRIES_PER_PAGE_GROUP(pg->order);
 			}
 
 			pages -= remaining;
-- 
2.45.2