spi: Cleanup on failure of initial setup

Commit c7299fea6769 ("spi: Fix spi device unregister flow") changed the
SPI core's behavior if the ->setup() hook returns an error upon adding
an spi_device:  Before, the ->cleanup() hook was invoked to free any
allocations that were made by ->setup().  With the commit, that's no
longer the case, so the ->setup() hook is expected to free the
allocations itself.

I've identified 5 drivers which depend on the old behavior and am fixing
them up hereinafter: spi-bitbang.c spi-fsl-spi.c spi-omap-uwire.c
spi-omap2-mcspi.c spi-pxa2xx.c

Importantly, ->setup() is not only invoked on spi_device *addition*:
It may subsequently be called to *change* SPI parameters.  If changing
these SPI parameters fails, freeing memory allocations would be wrong.
That should only be done if the spi_device is finally destroyed.
I am therefore using a bool "initial_setup" in 4 of the affected drivers
to differentiate between the invocation on *adding* the spi_device and
any subsequent invocations: spi-bitbang.c spi-fsl-spi.c spi-omap-uwire.c
spi-omap2-mcspi.c

In spi-pxa2xx.c, it seems the ->setup() hook can only fail on spi_device
addition, not any subsequent calls.  It therefore doesn't need the bool.

It's worth noting that 5 other drivers already perform a cleanup if the
->setup() hook fails.  Before c7299fea6769, they caused a double-free
if ->setup() failed on spi_device addition.  Since the commit, they're
fine.  These drivers are: spi-mpc512x-psc.c spi-pl022.c spi-s3c64xx.c
spi-st-ssc4.c spi-tegra114.c

(spi-pxa2xx.c also already performs a cleanup, but only in one of
several error paths.)

Fixes: c7299fea6769 ("spi: Fix spi device unregister flow")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Saravana Kannan <saravanak@google.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> # pxa2xx
Link: https://lore.kernel.org/r/f76a0599469f265b69c371538794101fa37b5536.1622149321.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index 6a6af85aebfd..27d0087f8688 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -184,6 +184,8 @@ int spi_bitbang_setup(struct spi_device *spi)
 {
 	struct spi_bitbang_cs	*cs = spi->controller_state;
 	struct spi_bitbang	*bitbang;
+	bool			initial_setup = false;
+	int			retval;
 
 	bitbang = spi_master_get_devdata(spi->master);
 
@@ -192,22 +194,30 @@ int spi_bitbang_setup(struct spi_device *spi)
 		if (!cs)
 			return -ENOMEM;
 		spi->controller_state = cs;
+		initial_setup = true;
 	}
 
 	/* per-word shift register access, in hardware or bitbanging */
 	cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
-	if (!cs->txrx_word)
-		return -EINVAL;
+	if (!cs->txrx_word) {
+		retval = -EINVAL;
+		goto err_free;
+	}
 
 	if (bitbang->setup_transfer) {
-		int retval = bitbang->setup_transfer(spi, NULL);
+		retval = bitbang->setup_transfer(spi, NULL);
 		if (retval < 0)
-			return retval;
+			goto err_free;
 	}
 
 	dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs);
 
 	return 0;
+
+err_free:
+	if (initial_setup)
+		kfree(cs);
+	return retval;
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_setup);