linux-kernel - [PATCH 10/13] frontswap: simplify frontswap_register

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211224062246.1258487-11-hch@lst.de>
Date:   Fri, 24 Dec 2021 07:22:43 +0100
From:   Christoph Hellwig <hch@....de>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     Hugh Dickins <hughd@...gle.com>,
        Seth Jennings <sjenning@...hat.com>,
        Dan Streetman <ddstreet@...e.org>,
        Vitaly Wool <vitaly.wool@...sulko.com>,
        Matthew Wilcox <willy@...radead.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH 10/13] frontswap: simplify frontswap_register_ops

Given that frontswap_register_ops must be called from built-in code,
there is no need to handle the case of swapfiles coming online before
or during it, so delete the code that deals with that case.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 mm/frontswap.c | 41 -----------------------------------------
 1 file changed, 41 deletions(-)

diff --git a/mm/frontswap.c b/mm/frontswap.c
index f51159f0d75d5..35040fa4eba83 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -99,25 +99,6 @@ static inline void inc_frontswap_invalidates(void) { }
  */
 void frontswap_register_ops(struct frontswap_ops *ops)
 {
-	DECLARE_BITMAP(a, MAX_SWAPFILES);
-	DECLARE_BITMAP(b, MAX_SWAPFILES);
-	struct swap_info_struct *si;
-	unsigned int i;
-
-	bitmap_zero(a, MAX_SWAPFILES);
-	bitmap_zero(b, MAX_SWAPFILES);
-
-	spin_lock(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list) {
-		if (!WARN_ON(!si->frontswap_map))
-			__set_bit(si->type, a);
-	}
-	spin_unlock(&swap_lock);
-
-	/* the new ops needs to know the currently active swap devices */
-	for_each_set_bit(i, a, MAX_SWAPFILES)
-		ops->init(i);
-
 	/*
 	 * Setting frontswap_ops must happen after the ops->init() calls
 	 * above; cmpxchg implies smp_mb() which will ensure the init is
@@ -128,28 +109,6 @@ void frontswap_register_ops(struct frontswap_ops *ops)
 	} while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next);
 
 	static_branch_inc(&frontswap_enabled_key);
-
-	spin_lock(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list) {
-		if (si->frontswap_map)
-			__set_bit(si->type, b);
-	}
-	spin_unlock(&swap_lock);
-
-	/*
-	 * On the very unlikely chance that a swap device was added or
-	 * removed between setting the "a" list bits and the ops init
-	 * calls, we re-check and do init or invalidate for any changed
-	 * bits.
-	 */
-	if (unlikely(!bitmap_equal(a, b, MAX_SWAPFILES))) {
-		for (i = 0; i < MAX_SWAPFILES; i++) {
-			if (!test_bit(i, a) && test_bit(i, b))
-				ops->init(i);
-			else if (test_bit(i, a) && !test_bit(i, b))
-				ops->invalidate_area(i);
-		}
-	}
 }
 
 /*
-- 
2.30.2