linux-kernel - [RFC PATCH 05/13] mm/damon/sysfs: remove damon_sysfs_cmd_request code from damon_sysfs_handle

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Message-Id: <20250226063651.513178-6-sj@kernel.org>
Date: Tue, 25 Feb 2025 22:36:43 -0800
From: SeongJae Park <sj@...nel.org>
To: 
Cc: SeongJae Park <sj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	damon@...ts.linux.dev,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [RFC PATCH 05/13] mm/damon/sysfs: remove damon_sysfs_cmd_request code from damon_sysfs_handle_cmd()

damon_sysfs_handle_cmd() handles user requests that it can directly
handle on its own.  For requests that need to be handled from
damon_callback hooks, it uses DAMON sysfs interface's own synchronous
damon_callback hooks management mechanism, namely
damon_sysfs_cmd_request.  Now all user requests are handled without
damon_callback hooks, so damon_sysfs_cmd_request use code in
damon_sysfs_andle_cmd() does nothing in real.  Remove the unnecessary
code.

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/sysfs.c | 32 --------------------------------
 1 file changed, 32 deletions(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index c55a2cee4b74..166161f12c26 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1715,8 +1715,6 @@ static int damon_sysfs_update_schemes_tried_regions(
 static int damon_sysfs_handle_cmd(enum damon_sysfs_cmd cmd,
 		struct damon_sysfs_kdamond *kdamond)
 {
-	bool need_wait = true;
-
 	switch (cmd) {
 	case DAMON_SYSFS_CMD_ON:
 		return damon_sysfs_turn_damon_on(kdamond);
@@ -1747,38 +1745,8 @@ static int damon_sysfs_handle_cmd(enum damon_sysfs_cmd cmd,
 		return damon_sysfs_damon_call(
 				damon_sysfs_upd_tuned_intervals, kdamond);
 	default:
-		break;
-	}
-
-	/* Pass the command to DAMON callback for safe DAMON context access */
-	if (damon_sysfs_cmd_request.kdamond)
-		return -EBUSY;
-	if (!damon_sysfs_kdamond_running(kdamond))
 		return -EINVAL;
-	damon_sysfs_cmd_request.cmd = cmd;
-	damon_sysfs_cmd_request.kdamond = kdamond;
-
-	/*
-	 * wait until damon_sysfs_cmd_request_callback() handles the request
-	 * from kdamond context
-	 */
-	mutex_unlock(&damon_sysfs_lock);
-	while (need_wait) {
-		schedule_timeout_idle(msecs_to_jiffies(100));
-		if (!mutex_trylock(&damon_sysfs_lock))
-			continue;
-		if (!damon_sysfs_cmd_request.kdamond) {
-			/* damon_sysfs_cmd_request_callback() handled */
-			need_wait = false;
-		} else if (!damon_sysfs_kdamond_running(kdamond)) {
-			/* kdamond has already finished */
-			need_wait = false;
-			damon_sysfs_cmd_request.kdamond = NULL;
-		}
-		mutex_unlock(&damon_sysfs_lock);
 	}
-	mutex_lock(&damon_sysfs_lock);
-	return 0;
 }
 
 static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
-- 
2.39.5