re: spi: spidev: Don't mangle max_speed_hz in underlying spi device

[Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

Hello Mark Brown,

This is a semi-automatic email about new static checker warnings.

The patch c4f5669ff40e: "spi: spidev: Don't mangle max_speed_hz i
underlying spi device" from Nov 8, 2014, leads to the following
Smatch complaint:

drivers/spi/spidev.c:581 spidev_release()
	 warn: variable dereferenced before check 'spidev->spi' (see line 577)

drivers/spi/spidev.c
   576
   577			spidev->speed_hz = spidev->spi->max_speed_hz;
                                           ^^^^^^^^^^^^^
New unchecked dereference.

   578
   579			/* ... after we unbound from the underlying device? */
   580			spin_lock_irq(&spidev->spi_lock);
   581			dofree = (spidev->spi == NULL);
                                  ^^^^^^^^^^^^^^^^^^^
Old code assumes ->spi can be NULL.

   582			spin_unlock_irq(&spidev->spi_lock);
   583

regards,
dan carpenter
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