usb: max-3421: Use driver data instead of maintaining a list of bound devices
Instead of maintaining a single-linked list of devices that must be searched linearly in .remove() just use spi_set_drvdata() to remember the link between the spi device and the driver struct. Then the global list and the next member can be dropped. This simplifies the driver, reduces the memory footprint and the time to search the list. Also it makes obvious that there is always a corresponding driver struct for a given device in .remove(), so the error path for !max3421_hcd can be dropped, too. As a side effect this fixes a data inconsistency when .probe() races with itself for a second max3421 device in manipulating max3421_hcd_list. A similar race is fixed in .remove(), too. Fixes: 2d53139f ("Add support for using a MAX3421E chip as a host driver.") Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20211018204028.2914597-1-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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