On 03/13/2018 05:18 PM, Laura Abbott wrote:
On 03/13/2018 02:13 AM, Phil Reid wrote:
On 10/03/2018 08:10, 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 <labb...@redhat.com>
  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..b7854850bcdb 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_ATOMIC);
+    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;

Doing this in an irq handler seems wrong.
Perhaps better if a buffer is pre-allocated in stmpe_gpio

Sure, I can pre-allocate the buffer in the probe.


Actually I wonder if there would be concurrency problems if we
tried to pre-allocate a global buffer. But the IRQ handler
calls stmpe_block_read which takes a mutex to sleep so I think
doing the (small) kmalloc should be fine and I can change it to


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