linux-kernel - [PATCH v2 2/4] livepatch/shadow: Separate code removing all shadow variables for a given id

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Message-Id: <20221026194122.11761-3-mpdesouza@suse.com>
Date:   Wed, 26 Oct 2022 16:41:20 -0300
From:   Marcos Paulo de Souza <mpdesouza@...e.com>
To:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org
Cc:     jpoimboe@...hat.com, joe.lawrence@...hat.com, pmladek@...e.com,
        Marcos Paulo de Souza <mpdesouza@...e.com>
Subject: [PATCH v2 2/4] livepatch/shadow: Separate code removing all shadow variables for a given id

From: Petr Mladek <pmladek@...e.com>

Allow to remove all shadow variables with already taken klp_shadow_lock.
It will be needed to synchronize this with other operation during
the garbage collection of shadow variables.

It is a code refactoring without any functional changes.

Signed-off-by: Petr Mladek <pmladek@...e.com>
Reviewed-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
---
 Changes from v1:
 * Added my SoB (Josh)

 kernel/livepatch/shadow.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/kernel/livepatch/shadow.c b/kernel/livepatch/shadow.c
index 81ad7cbbd124..aba44dcc0a88 100644
--- a/kernel/livepatch/shadow.c
+++ b/kernel/livepatch/shadow.c
@@ -283,6 +283,20 @@ void klp_shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
 }
 EXPORT_SYMBOL_GPL(klp_shadow_free);
 
+static void __klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
+{
+	struct klp_shadow *shadow;
+	int i;
+
+	lockdep_assert_held(&klp_shadow_lock);
+
+	/* Delete all <*, id> from hash */
+	hash_for_each(klp_shadow_hash, i, shadow, node) {
+		if (klp_shadow_match(shadow, shadow->obj, id))
+			klp_shadow_free_struct(shadow, dtor);
+	}
+}
+
 /**
  * klp_shadow_free_all() - detach and free all <_, id> shadow variables
  * @id:		data identifier
@@ -294,18 +308,10 @@ EXPORT_SYMBOL_GPL(klp_shadow_free);
  */
 void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
 {
-	struct klp_shadow *shadow;
 	unsigned long flags;
-	int i;
 
 	spin_lock_irqsave(&klp_shadow_lock, flags);
-
-	/* Delete all <_, id> from hash */
-	hash_for_each(klp_shadow_hash, i, shadow, node) {
-		if (klp_shadow_match(shadow, shadow->obj, id))
-			klp_shadow_free_struct(shadow, dtor);
-	}
-
+	__klp_shadow_free_all(id, dtor);
 	spin_unlock_irqrestore(&klp_shadow_lock, flags);
 }
 EXPORT_SYMBOL_GPL(klp_shadow_free_all);
-- 
2.37.3