Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Jinlong Chen <nickyc975@zju.edu.cn>
To:     axboe@kernel.dk
Cc:     hch@lst.de, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, nickyc975@zju.edu.cn
Subject: [PATCH 1/4] elevator: update the document of elevator_switch
Date:   Tue, 22 Nov 2022 22:21:23 +0800
Message-Id: <94250961689ba7d2e67a7d9e7995a11166fedb31.1669126766.git.nickyc975@zju.edu.cn>
In-Reply-To: <cover.1669126766.git.nickyc975@zju.edu.cn>
References: <cover.1669126766.git.nickyc975@zju.edu.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

We no longer support falling back to the old io scheduler if switching to
the new one fails. Update the document to indicate that.

Fixes: a1ce35fa4985 ("block: remove dead elevator code")
Signed-off-by: Jinlong Chen <nickyc975@zju.edu.cn>
---
 block/elevator.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/elevator.c b/block/elevator.c
index a5bdc3b1e7e5..01aa9f38f22e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -650,10 +650,10 @@ void elevator_init_mq(struct request_queue *q)
 }
 
 /*
- * switch to new_e io scheduler. be careful not to introduce deadlocks -
- * we don't free the old io scheduler, before we have allocated what we
- * need for the new one. this way we have a chance of going back to the old
- * one, if the new one fails init for some reason.
+ * Switch to new_e io scheduler.
+ *
+ * If switching fails, we are most likely running out of memory and not able
+ * to restore the old io scheduler, so leaving the io scheduler being none.
  */
 int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 {
-- 
2.34.1