linux-kernel - [PATCH] memstick: Skip allocating card when removing host

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Message-Id: <20200925084952.13220-1-kai.heng.feng@canonical.com>
Date:   Fri, 25 Sep 2020 16:49:51 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     ulf.hansson@...aro.org
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Maxim Levitsky <maximlevitsky@...il.com>,
        Alex Dubov <oakad@...oo.com>,
        linux-mmc@...r.kernel.org (open list:SONY MEMORYSTICK SUBSYSTEM),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] memstick: Skip allocating card when removing host

After commit 6827ca573c03 ("memstick: rtsx_usb_ms: Support runtime power
management"), removing module rtsx_usb_ms will be stuck.

The deadlock is caused by powering on and powering off at the same time,
the former one is when memstick_check() is flushed, and the later is called
by memstick_remove_host().

Soe let's skip allocating card to prevent this issue.

Fixes: 6827ca573c03 ("memstick: rtsx_usb_ms: Support runtime power management")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/memstick/core/memstick.c | 4 ++++
 include/linux/memstick.h         | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/memstick/core/memstick.c b/drivers/memstick/core/memstick.c
index 693ee73eb291..ef03d6fafc5c 100644
--- a/drivers/memstick/core/memstick.c
+++ b/drivers/memstick/core/memstick.c
@@ -441,6 +441,9 @@ static void memstick_check(struct work_struct *work)
 	} else if (host->card->stop)
 		host->card->stop(host->card);
 
+	if (host->removing)
+		goto out_power_off;
+
 	card = memstick_alloc_card(host);
 
 	if (!card) {
@@ -545,6 +548,7 @@ EXPORT_SYMBOL(memstick_add_host);
  */
 void memstick_remove_host(struct memstick_host *host)
 {
+	host->removing = 1;
 	flush_workqueue(workqueue);
 	mutex_lock(&host->lock);
 	if (host->card)
diff --git a/include/linux/memstick.h b/include/linux/memstick.h
index da4c65f9435f..ebf73d4ee969 100644
--- a/include/linux/memstick.h
+++ b/include/linux/memstick.h
@@ -281,6 +281,7 @@ struct memstick_host {
 
 	struct memstick_dev *card;
 	unsigned int        retries;
+	bool removing;
 
 	/* Notify the host that some requests are pending. */
 	void                (*request)(struct memstick_host *host);
-- 
2.17.1