linux-kernel - [PATCH] spi: spi-topcliff-pch: Replace GFP_ATOMIC with GFP_KERNEL in pch_spi_handle

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Date:   Tue, 10 Apr 2018 17:06:16 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     broonie@...nel.org
Cc:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] spi: spi-topcliff-pch: Replace GFP_ATOMIC with GFP_KERNEL in pch_spi_handle_dma

pch_spi_handle_dma() is never called in atomic context.
This function is only called by pch_spi_process_messages().
pch_spi_process_messages() is only set as a parameter of INIT_WORK() in
pch_spi_pd_probe().

Despite never getting called from atomic context,
pch_spi_handle_dma() calls kcalloc() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/spi/spi-topcliff-pch.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-topcliff-pch.c b/drivers/spi/spi-topcliff-pch.c
index 97d1375..dc93ca9 100644
--- a/drivers/spi/spi-topcliff-pch.c
+++ b/drivers/spi/spi-topcliff-pch.c
@@ -1007,7 +1007,7 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw)
 	spin_unlock_irqrestore(&data->lock, flags);
 
 	/* RX */
-	dma->sg_rx_p = kcalloc(num, sizeof(*dma->sg_rx_p), GFP_ATOMIC);
+	dma->sg_rx_p = kcalloc(num, sizeof(*dma->sg_rx_p), GFP_KERNEL);
 	sg_init_table(dma->sg_rx_p, num); /* Initialize SG table */
 	/* offset, length setting */
 	sg = dma->sg_rx_p;
@@ -1067,7 +1067,7 @@ static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw)
 		head = 0;
 	}
 
-	dma->sg_tx_p = kcalloc(num, sizeof(*dma->sg_tx_p), GFP_ATOMIC);
+	dma->sg_tx_p = kcalloc(num, sizeof(*dma->sg_tx_p), GFP_KERNEL);
 	sg_init_table(dma->sg_tx_p, num); /* Initialize SG table */
 	/* offset, length setting */
 	sg = dma->sg_tx_p;
-- 
1.9.1