This is a note to let you know that I've just added the patch titled usb: max-3421: Use driver data instead of maintaining a list of bound devices to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-max-3421-use-driver-data-instead-of-maintaining-a-list-of-bound-devices.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From fc153aba3ef371d0d76eb88230ed4e0dee5b38f2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@xxxxxxxxxxxxxx> Date: Mon, 18 Oct 2021 22:40:28 +0200 Subject: usb: max-3421: Use driver data instead of maintaining a list of bound devices MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> commit fc153aba3ef371d0d76eb88230ed4e0dee5b38f2 upstream. 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: 2d53139f3162 ("Add support for using a MAX3421E chip as a host driver.") Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20211018204028.2914597-1-u.kleine-koenig@xxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/host/max3421-hcd.c | 25 +++++-------------------- 1 file changed, 5 insertions(+), 20 deletions(-) --- a/drivers/usb/host/max3421-hcd.c +++ b/drivers/usb/host/max3421-hcd.c @@ -121,8 +121,6 @@ struct max3421_hcd { struct task_struct *spi_thread; - struct max3421_hcd *next; - enum max3421_rh_state rh_state; /* lower 16 bits contain port status, upper 16 bits the change mask: */ u32 port_status; @@ -170,8 +168,6 @@ struct max3421_ep { u8 retransmit; /* packet needs retransmission */ }; -static struct max3421_hcd *max3421_hcd_list; - #define MAX3421_FIFO_SIZE 64 #define MAX3421_SPI_DIR_RD 0 /* read register from MAX3421 */ @@ -1841,9 +1837,8 @@ max3421_probe(struct spi_device *spi) } set_bit(HCD_FLAG_POLL_RH, &hcd->flags); max3421_hcd = hcd_to_max3421(hcd); - max3421_hcd->next = max3421_hcd_list; - max3421_hcd_list = max3421_hcd; INIT_LIST_HEAD(&max3421_hcd->ep_list); + spi_set_drvdata(spi, max3421_hcd); max3421_hcd->tx = kmalloc(sizeof(*max3421_hcd->tx), GFP_KERNEL); if (!max3421_hcd->tx) { @@ -1892,28 +1887,18 @@ error: static int max3421_remove(struct spi_device *spi) { - struct max3421_hcd *max3421_hcd = NULL, **prev; - struct usb_hcd *hcd = NULL; + struct max3421_hcd *max3421_hcd; + struct usb_hcd *hcd; unsigned long flags; - for (prev = &max3421_hcd_list; *prev; prev = &(*prev)->next) { - max3421_hcd = *prev; - hcd = max3421_to_hcd(max3421_hcd); - if (hcd->self.controller == &spi->dev) - break; - } - if (!max3421_hcd) { - dev_err(&spi->dev, "no MAX3421 HCD found for SPI device %p\n", - spi); - return -ENODEV; - } + max3421_hcd = spi_get_drvdata(spi); + hcd = max3421_to_hcd(max3421_hcd); usb_remove_hcd(hcd); spin_lock_irqsave(&max3421_hcd->lock, flags); kthread_stop(max3421_hcd->spi_thread); - *prev = max3421_hcd->next; spin_unlock_irqrestore(&max3421_hcd->lock, flags); Patches currently in stable-queue which might be from u.kleine-koenig@xxxxxxxxxxxxxx are queue-4.4/usb-max-3421-use-driver-data-instead-of-maintaining-a-list-of-bound-devices.patch