linux-kernel - [PATCH AUTOSEL 4.19 1/7] mmc: atmel-mci: fix race between stop command and start of next command

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Date:   Tue, 14 Mar 2023 08:44:18 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Tobias Schramm <t.schramm@...jaro.org>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Sasha Levin <sashal@...nel.org>, linux-mmc@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 1/7] mmc: atmel-mci: fix race between stop command and start of next command

From: Tobias Schramm <t.schramm@...jaro.org>

[ Upstream commit eca5bd666b0aa7dc0bca63292e4778968241134e ]

This commit fixes a race between completion of stop command and start of a
new command.
Previously the command ready interrupt was enabled before stop command
was written to the command register. This caused the command ready
interrupt to fire immediately since the CMDRDY flag is asserted constantly
while there is no command in progress.
Consequently the command state machine will immediately advance to the
next state when the tasklet function is executed again, no matter
actual completion state of the stop command.
Thus a new command can then be dispatched immediately, interrupting and
corrupting the stop command on the CMD line.
Fix that by dropping the command ready interrupt enable before calling
atmci_send_stop_cmd. atmci_send_stop_cmd does already enable the
command ready interrupt, no further writes to ATMCI_IER are necessary.

Signed-off-by: Tobias Schramm <t.schramm@...jaro.org>
Acked-by: Ludovic Desroches <ludovic.desroches@...rochip.com>
Link: https://lore.kernel.org/r/20221230194315.809903-2-t.schramm@manjaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/mmc/host/atmel-mci.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index d40bab3d9f4af..fb435a8d37213 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -1857,7 +1857,6 @@ static void atmci_tasklet_func(unsigned long priv)
 				atmci_writel(host, ATMCI_IER, ATMCI_NOTBUSY);
 				state = STATE_WAITING_NOTBUSY;
 			} else if (host->mrq->stop) {
-				atmci_writel(host, ATMCI_IER, ATMCI_CMDRDY);
 				atmci_send_stop_cmd(host, data);
 				state = STATE_SENDING_STOP;
 			} else {
@@ -1890,8 +1889,6 @@ static void atmci_tasklet_func(unsigned long priv)
 				 * command to send.
 				 */
 				if (host->mrq->stop) {
-					atmci_writel(host, ATMCI_IER,
-					             ATMCI_CMDRDY);
 					atmci_send_stop_cmd(host, data);
 					state = STATE_SENDING_STOP;
 				} else {
-- 
2.39.2