mm/damon/sysfs: remove damon_sysfs_cmd_request and its readers

damon_sysfs_cmd_request is DAMON sysfs interface's own synchronization
mechanism for accessing DAMON internal data via damon_callback hooks.  All
the users are now migrated to damon_call() and damos_walk(), so nobody
really uses it.  No one writes to the data structure but reading code is
still remained.  Remove the reading code and the entire data structure.

Link: https://lkml.kernel.org/r/20250306175908.66300-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index e5bcf019086fc0503f26da7dc36cea1613f4e189..1af6aff35d84a09de69fbfdd45ed31b519dbec14 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1238,25 +1238,6 @@ static const char * const damon_sysfs_cmd_strs[] = {
        "update_tuned_intervals",
 };
 
-/*
- * struct damon_sysfs_cmd_request - A request to the DAMON callback.
- * @cmd:       The command that needs to be handled by the callback.
- * @kdamond:   The kobject wrapper that associated to the kdamond thread.
- *
- * This structure represents a sysfs command request that need to access some
- * DAMON context-internal data.  Because DAMON context-internal data can be
- * safely accessed from DAMON callbacks without additional synchronization, the
- * request will be handled by the DAMON callback.  None-``NULL`` @kdamond means
- * the request is valid.
- */
-struct damon_sysfs_cmd_request {
-       enum damon_sysfs_cmd cmd;
-       struct damon_sysfs_kdamond *kdamond;
-};
-
-/* Current DAMON callback request.  Protected by damon_sysfs_lock. */
-static struct damon_sysfs_cmd_request damon_sysfs_cmd_request;
-
 static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
                char *buf)
 {
@@ -1555,8 +1536,6 @@ static int damon_sysfs_turn_damon_on(struct damon_sysfs_kdamond *kdamond)
 
        if (damon_sysfs_kdamond_running(kdamond))
                return -EBUSY;
-       if (damon_sysfs_cmd_request.kdamond == kdamond)
-               return -EBUSY;
        /* TODO: support multiple contexts per kdamond */
        if (kdamond->contexts->nr != 1)
                return -EINVAL;
@@ -1796,8 +1775,7 @@ static bool damon_sysfs_kdamonds_busy(struct damon_sysfs_kdamond **kdamonds,
        int i;
 
        for (i = 0; i < nr_kdamonds; i++) {
-               if (damon_sysfs_kdamond_running(kdamonds[i]) ||
-                   damon_sysfs_cmd_request.kdamond == kdamonds[i])
+               if (damon_sysfs_kdamond_running(kdamonds[i]))
                        return true;
        }