linux-kernel - [PATCH 5.8 025/464] rcu/tree: Repeat the monitor if any free channel is busy

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20200817143834.962809584@linuxfoundation.org>
Date:   Mon, 17 Aug 2020 17:09:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 025/464] rcu/tree: Repeat the monitor if any free channel is busy

From: Uladzislau Rezki (Sony) <urezki@...il.com>

[ Upstream commit 594aa5975b9b5cfe9edaec06170e43b8c0607377 ]

It is possible that one of the channels cannot be detached
because its free channel is busy and previously queued data
has not been processed yet. On the other hand, another
channel can be successfully detached causing the monitor
work to stop.

Prevent that by rescheduling the monitor work if there are
any channels in the pending state after a detach attempt.

Fixes: 34c881745549e ("rcu: Support kfree_bulk() interface in kfree_rcu()")
Acked-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/rcu/tree.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 6c6569e0586c5..1e9e500ff7906 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3105,7 +3105,7 @@ static void kfree_rcu_work(struct work_struct *work)
 static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp)
 {
 	struct kfree_rcu_cpu_work *krwp;
-	bool queued = false;
+	bool repeat = false;
 	int i;
 
 	lockdep_assert_held(&krcp->lock);
@@ -3143,11 +3143,14 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp)
 			 * been detached following each other, one by one.
 			 */
 			queue_rcu_work(system_wq, &krwp->rcu_work);
-			queued = true;
 		}
+
+		/* Repeat if any "free" corresponding channel is still busy. */
+		if (krcp->bhead || krcp->head)
+			repeat = true;
 	}
 
-	return queued;
+	return !repeat;
 }
 
 static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp,
-- 
2.25.1