mm/damon/sysfs: use damon_call() for update_schemes_stats

DAMON sysfs interface uses damon_callback with its own synchronization
facility to handle update_schemes_stats kdamond command.  But damon_call()
can support the use case without the additional synchronizations.  Convert
the code to use damon_call() instead.

Link: https://lkml.kernel.org/r/20250103174400.54890-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 4f6e4720b7ce2ede5318d16af54806bd36d5072f..708c2ffdd620c6216836722a161e1bd6f6966037 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1214,19 +1214,19 @@ static void damon_sysfs_before_terminate(struct damon_ctx *ctx)
 
 /*
  * damon_sysfs_upd_schemes_stats() - Update schemes stats sysfs files.
- * @kdamond:   The kobject wrapper that associated to the kdamond thread.
+ * @data:      The kobject wrapper that associated to the kdamond thread.
  *
  * This function reads the schemes stats of specific kdamond and update the
  * related values for sysfs files.  This function should be called from DAMON
- * callbacks while holding ``damon_syfs_lock``, to safely access the DAMON
- * contexts-internal data and DAMON sysfs variables.
+ * worker thread,to safely access the DAMON contexts-internal data.  Caller
+ * should also ensure holding ``damon_syfs_lock``, and ->damon_ctx of @data is
+ * not NULL but a valid pointer, to safely access DAMON sysfs variables.
  */
-static int damon_sysfs_upd_schemes_stats(struct damon_sysfs_kdamond *kdamond)
+static int damon_sysfs_upd_schemes_stats(void *data)
 {
+       struct damon_sysfs_kdamond *kdamond = data;
        struct damon_ctx *ctx = kdamond->damon_ctx;
 
-       if (!ctx)
-               return -EINVAL;
        damon_sysfs_schemes_update_stats(
                        kdamond->contexts->contexts_arr[0]->schemes, ctx);
        return 0;
@@ -1371,9 +1371,6 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active,
        if (!kdamond || kdamond->damon_ctx != c)
                goto out;
        switch (damon_sysfs_cmd_request.cmd) {
-       case DAMON_SYSFS_CMD_UPDATE_SCHEMES_STATS:
-               err = damon_sysfs_upd_schemes_stats(kdamond);
-               break;
        case DAMON_SYSFS_CMD_COMMIT:
                if (!after_aggregation)
                        goto out;
@@ -1511,6 +1508,18 @@ static int damon_sysfs_turn_damon_off(struct damon_sysfs_kdamond *kdamond)
         */
 }
 
+static int damon_sysfs_damon_call(int (*fn)(void *data),
+               struct damon_sysfs_kdamond *kdamond)
+{
+       struct damon_call_control call_control = {};
+
+       if (!kdamond->damon_ctx)
+               return -EINVAL;
+       call_control.fn = fn;
+       call_control.data = kdamond;
+       return damon_call(kdamond->damon_ctx, &call_control);
+}
+
 /*
  * damon_sysfs_handle_cmd() - Handle a command for a specific kdamond.
  * @cmd:       The command to handle.
@@ -1529,12 +1538,14 @@ static int damon_sysfs_handle_cmd(enum damon_sysfs_cmd cmd,
 {
        bool need_wait = true;
 
-       /* Handle commands that doesn't access DAMON context-internal data */
        switch (cmd) {
        case DAMON_SYSFS_CMD_ON:
                return damon_sysfs_turn_damon_on(kdamond);
        case DAMON_SYSFS_CMD_OFF:
                return damon_sysfs_turn_damon_off(kdamond);
+       case DAMON_SYSFS_CMD_UPDATE_SCHEMES_STATS:
+               return damon_sysfs_damon_call(
+                               damon_sysfs_upd_schemes_stats, kdamond);
        case DAMON_SYSFS_CMD_CLEAR_SCHEMES_TRIED_REGIONS:
                return damon_sysfs_schemes_clear_regions(
                        kdamond->contexts->contexts_arr[0]->schemes);