Re: [PATCHv2 4/4] gpio: Remove VLA from stmpe driver

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On 16/03/2018 02:00, Laura Abbott wrote:
The new challenge is to remove VLAs from the kernel
(see https://lkml.org/lkml/2018/3/7/621)

This patch replaces a VLA with an appropriate call to kmalloc_array.

Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
---
v2: Switch to GFP_KERNEL. There was some discussion about if we should
be doing the allocation at all but given a) the allocation is pretty
small and b) we can possibly take a mutex in a called function I think
this is fine.

I still think it's a bad idea. It's simple to preallocate the buffer.
But it's up to the maintainer.


---
  drivers/gpio/gpio-stmpe.c | 7 ++++++-
  1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-stmpe.c b/drivers/gpio/gpio-stmpe.c
index f8d7d1cd8488..c2bb20ace6f5 100644
--- a/drivers/gpio/gpio-stmpe.c
+++ b/drivers/gpio/gpio-stmpe.c
@@ -369,10 +369,14 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
  	struct stmpe *stmpe = stmpe_gpio->stmpe;
  	u8 statmsbreg;
  	int num_banks = DIV_ROUND_UP(stmpe->num_gpios, 8);
-	u8 status[num_banks];
+	u8 *status;
  	int ret;
  	int i;
+ status = kmalloc_array(num_banks, sizeof(*status), GFP_KERNEL);
+	if (!status)
+		return IRQ_NONE;
+
  	/*
  	 * the stmpe_block_read() call below, imposes to set statmsbreg
  	 * with the register located at the lowest address. As STMPE1600
@@ -424,6 +428,7 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
  		}
  	}
+ kfree(status);
  	return IRQ_HANDLED;
  }


--
Regards
Phil Reid
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