From b2c8daddcbe03a22402ecf943bb88302601c6835 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Thu, 5 Jun 2008 22:45:50 -0700 Subject: [PATCH] spi: fix refcount-related spidev oops-on-rmmod This addresses other oopsing paths in "spidev" by changing how it manages refcounting. It decouples the lifecycle of the per-device data from the class device (not just the spi device): - Use class_{create,destroy} not class_{register,unregister}. - Use device_{create,destroy} not device_{register,unregister}. - Free the per-device data only when TWO conditions are true: * Driver is unbound from underlying SPI device, and * Device is no longer open (new) Also, spi_{get,set}_drvdata not dev_{get,set}_drvdata for simpler code. Signed-off-by: David Brownell Sebastian Siewior Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/spi/spidev.c | 64 +++++++++++++++++++++++--------------------- 1 file changed, 34 insertions(+), 30 deletions(-) diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index 41620c0fb04..799337f7fde 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -67,11 +68,12 @@ static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG]; | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP) struct spidev_data { - struct device dev; + dev_t devt; spinlock_t spi_lock; struct spi_device *spi; struct list_head device_entry; + /* buffer is NULL unless this device is open (users > 0) */ struct mutex buf_lock; unsigned users; u8 *buffer; @@ -467,7 +469,7 @@ static int spidev_open(struct inode *inode, struct file *filp) mutex_lock(&device_list_lock); list_for_each_entry(spidev, &device_list, device_entry) { - if (spidev->dev.devt == inode->i_rdev) { + if (spidev->devt == inode->i_rdev) { status = 0; break; } @@ -500,10 +502,22 @@ static int spidev_release(struct inode *inode, struct file *filp) mutex_lock(&device_list_lock); spidev = filp->private_data; filp->private_data = NULL; + + /* last close? */ spidev->users--; if (!spidev->users) { + int dofree; + kfree(spidev->buffer); spidev->buffer = NULL; + + /* ... after we unbound from the underlying device? */ + spin_lock_irq(&spidev->spi_lock); + dofree = (spidev->spi == NULL); + spin_unlock_irq(&spidev->spi_lock); + + if (dofree) + kfree(spidev); } mutex_unlock(&device_list_lock); @@ -530,19 +544,7 @@ static struct file_operations spidev_fops = { * It also simplifies memory management. */ -static void spidev_classdev_release(struct device *dev) -{ - struct spidev_data *spidev; - - spidev = container_of(dev, struct spidev_data, dev); - kfree(spidev); -} - -static struct class spidev_class = { - .name = "spidev", - .owner = THIS_MODULE, - .dev_release = spidev_classdev_release, -}; +static struct class *spidev_class; /*-------------------------------------------------------------------------*/ @@ -570,20 +572,20 @@ static int spidev_probe(struct spi_device *spi) mutex_lock(&device_list_lock); minor = find_first_zero_bit(minors, N_SPI_MINORS); if (minor < N_SPI_MINORS) { - spidev->dev.parent = &spi->dev; - spidev->dev.class = &spidev_class; - spidev->dev.devt = MKDEV(SPIDEV_MAJOR, minor); - snprintf(spidev->dev.bus_id, sizeof spidev->dev.bus_id, + struct device *dev; + + spidev->devt = MKDEV(SPIDEV_MAJOR, minor); + dev = device_create(spidev_class, &spi->dev, spidev->devt, "spidev%d.%d", spi->master->bus_num, spi->chip_select); - status = device_register(&spidev->dev); + status = IS_ERR(dev) ? PTR_ERR(dev) : 0; } else { dev_dbg(&spi->dev, "no minor number available!\n"); status = -ENODEV; } if (status == 0) { set_bit(minor, minors); - dev_set_drvdata(&spi->dev, spidev); + spi_set_drvdata(spi, spidev); list_add(&spidev->device_entry, &device_list); } mutex_unlock(&device_list_lock); @@ -596,19 +598,21 @@ static int spidev_probe(struct spi_device *spi) static int spidev_remove(struct spi_device *spi) { - struct spidev_data *spidev = dev_get_drvdata(&spi->dev); + struct spidev_data *spidev = spi_get_drvdata(spi); /* make sure ops on existing fds can abort cleanly */ spin_lock_irq(&spidev->spi_lock); spidev->spi = NULL; + spi_set_drvdata(spi, NULL); spin_unlock_irq(&spidev->spi_lock); /* prevent new opens */ mutex_lock(&device_list_lock); list_del(&spidev->device_entry); - dev_set_drvdata(&spi->dev, NULL); - clear_bit(MINOR(spidev->dev.devt), minors); - device_unregister(&spidev->dev); + device_destroy(spidev_class, spidev->devt); + clear_bit(MINOR(spidev->devt), minors); + if (spidev->users == 0) + kfree(spidev); mutex_unlock(&device_list_lock); return 0; @@ -644,15 +648,15 @@ static int __init spidev_init(void) if (status < 0) return status; - status = class_register(&spidev_class); - if (status < 0) { + spidev_class = class_create(THIS_MODULE, "spidev"); + if (IS_ERR(spidev_class)) { unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); - return status; + return PTR_ERR(spidev_class); } status = spi_register_driver(&spidev_spi); if (status < 0) { - class_unregister(&spidev_class); + class_destroy(spidev_class); unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); } return status; @@ -662,7 +666,7 @@ module_init(spidev_init); static void __exit spidev_exit(void) { spi_unregister_driver(&spidev_spi); - class_unregister(&spidev_class); + class_destroy(spidev_class); unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); } module_exit(spidev_exit); -- 2.20.1