linux-kernel - [PATCH 2/4] mm/swap_cgroup: remove swap_cgroup

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Message-ID: <20241202184154.19321-3-ryncsn@gmail.com>
Date: Tue,  3 Dec 2024 02:41:52 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Chris Li <chrisl@...nel.org>,
	Hugh Dickins <hughd@...gle.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	Yosry Ahmed <yosryahmed@...gle.com>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Johannes Weiner <hannes@...xchg.org>,
	Barry Song <baohua@...nel.org>,
	Michal Hocko <mhocko@...nel.org>,
	linux-kernel@...r.kernel.org,
	Kairui Song <kasong@...cent.com>
Subject: [PATCH 2/4] mm/swap_cgroup: remove swap_cgroup_cmpxchg

From: Kairui Song <kasong@...cent.com>

This function is never used after commit 6b611388b626
("memcg-v1: remove charge move code").

Signed-off-by: Kairui Song <kasong@...cent.com>
---
 include/linux/swap_cgroup.h |  2 --
 mm/swap_cgroup.c            | 29 -----------------------------
 2 files changed, 31 deletions(-)

diff --git a/include/linux/swap_cgroup.h b/include/linux/swap_cgroup.h
index ae73a87775b3..d521ad1c4164 100644
--- a/include/linux/swap_cgroup.h
+++ b/include/linux/swap_cgroup.h
@@ -6,8 +6,6 @@
 
 #if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
 
-extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
-					unsigned short old, unsigned short new);
 extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id,
 					 unsigned int nr_ents);
 extern unsigned short lookup_swap_cgroup_id(swp_entry_t ent);
diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index f63d1aa072a1..1770b076f6b7 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -45,35 +45,6 @@ static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
 	return &ctrl->map[offset];
 }
 
-/**
- * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
- * @ent: swap entry to be cmpxchged
- * @old: old id
- * @new: new id
- *
- * Returns old id at success, 0 at failure.
- * (There is no mem_cgroup using 0 as its id)
- */
-unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
-					unsigned short old, unsigned short new)
-{
-	struct swap_cgroup_ctrl *ctrl;
-	struct swap_cgroup *sc;
-	unsigned long flags;
-	unsigned short retval;
-
-	sc = lookup_swap_cgroup(ent, &ctrl);
-
-	spin_lock_irqsave(&ctrl->lock, flags);
-	retval = sc->id;
-	if (retval == old)
-		sc->id = new;
-	else
-		retval = 0;
-	spin_unlock_irqrestore(&ctrl->lock, flags);
-	return retval;
-}
-
 /**
  * swap_cgroup_record - record mem_cgroup for a set of swap entries
  * @ent: the first swap entry to be recorded into
-- 
2.47.0