linux-kernel - [PATCH 3.18 06/24] spi: atmel: fixed spin_lock usage inside atmel_spi

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Date:   Fri,  2 Mar 2018 09:51:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>,
        Radu Pirea <radu.pirea@...rochip.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 3.18 06/24] spi: atmel: fixed spin_lock usage inside atmel_spi_remove

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Radu Pirea <radu.pirea@...rochip.com>


[ Upstream commit 66e900a3d225575c8b48b59ae1fe74bb6e5a65cc ]

The only part of atmel_spi_remove which needs to be atomic is hardware
reset.

atmel_spi_stop_dma calls dma_terminate_all and this needs interrupts
enabled.
atmel_spi_release_dma calls dma_release_channel and dma_release_channel
locks a mutex inside of spin_lock.

So the call of these functions can't be inside a spin_lock.

Reported-by: Jia-Ju Bai <baijiaju1990@...il.com>
Signed-off-by: Radu Pirea <radu.pirea@...rochip.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/spi/spi-atmel.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -1416,12 +1416,12 @@ static int atmel_spi_remove(struct platf
 	struct atmel_spi	*as = spi_master_get_devdata(master);
 
 	/* reset the hardware and block queue progress */
-	spin_lock_irq(&as->lock);
 	if (as->use_dma) {
 		atmel_spi_stop_dma(as);
 		atmel_spi_release_dma(as);
 	}
 
+	spin_lock_irq(&as->lock);
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 	spi_readl(as, SR);