From 8a932f73e5b4227bf787474b44dc70b6961d6246 Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Thu, 15 Jun 2017 14:05:21 -0600 Subject: [PATCH] char_dev: order /proc/devices by major number Presently, the order of the char devices listed in /proc/devices is not entirely sequential. If a char device has a major number greater than CHRDEV_MAJOR_HASH_SIZE (255), it will be ordered as if its major were module 255. For example, 511 appears after 1. This patch cleans that up and prints each major number in the correct order, regardless of where they are stored in the hash table. In order to do this, we introduce CHRDEV_MAJOR_MAX as an artificial limit (chosen to be 511). It will then print all devices in major order number from 0 to the maximum. Signed-off-by: Logan Gunthorpe Cc: Linus Torvalds Cc: Greg Kroah-Hartman Cc: Alan Cox Cc: Arnd Bergmann Cc: Linus Walleij Signed-off-by: Greg Kroah-Hartman --- fs/char_dev.c | 17 +++++++++++++---- fs/proc/devices.c | 8 ++++---- include/linux/fs.h | 2 +- 3 files changed, 18 insertions(+), 9 deletions(-) diff --git a/fs/char_dev.c b/fs/char_dev.c index c9d18362e89d..ebcc8fb3fa66 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -28,6 +28,8 @@ static struct kobj_map *cdev_map; static DEFINE_MUTEX(chrdevs_lock); +#define CHRDEV_MAJOR_HASH_SIZE 255 + static struct char_device_struct { struct char_device_struct *next; unsigned int major; @@ -49,12 +51,12 @@ void chrdev_show(struct seq_file *f, off_t offset) { struct char_device_struct *cd; - if (offset < CHRDEV_MAJOR_HASH_SIZE) { - mutex_lock(&chrdevs_lock); - for (cd = chrdevs[offset]; cd; cd = cd->next) + mutex_lock(&chrdevs_lock); + for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) { + if (cd->major == offset) seq_printf(f, "%3d %s\n", cd->major, cd->name); - mutex_unlock(&chrdevs_lock); } + mutex_unlock(&chrdevs_lock); } #endif /* CONFIG_PROC_FS */ @@ -117,6 +119,13 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor, major = ret; } + if (major >= CHRDEV_MAJOR_MAX) { + pr_err("CHRDEV \"%s\" major requested (%d) is greater than the maximum (%d)\n", + name, major, CHRDEV_MAJOR_MAX); + ret = -EINVAL; + goto out; + } + cd->major = major; cd->baseminor = baseminor; cd->minorct = minorct; diff --git a/fs/proc/devices.c b/fs/proc/devices.c index 50493edc30e5..d196e22c4f1c 100644 --- a/fs/proc/devices.c +++ b/fs/proc/devices.c @@ -7,14 +7,14 @@ static int devinfo_show(struct seq_file *f, void *v) { int i = *(loff_t *) v; - if (i < CHRDEV_MAJOR_HASH_SIZE) { + if (i < CHRDEV_MAJOR_MAX) { if (i == 0) seq_puts(f, "Character devices:\n"); chrdev_show(f, i); } #ifdef CONFIG_BLOCK else { - i -= CHRDEV_MAJOR_HASH_SIZE; + i -= CHRDEV_MAJOR_MAX; if (i == 0) seq_puts(f, "\nBlock devices:\n"); blkdev_show(f, i); @@ -25,7 +25,7 @@ static int devinfo_show(struct seq_file *f, void *v) static void *devinfo_start(struct seq_file *f, loff_t *pos) { - if (*pos < (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE)) + if (*pos < (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_MAX)) return pos; return NULL; } @@ -33,7 +33,7 @@ static void *devinfo_start(struct seq_file *f, loff_t *pos) static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos) { (*pos)++; - if (*pos >= (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE)) + if (*pos >= (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_MAX)) return NULL; return pos; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 1773dcf1e318..b07433c335ca 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2470,7 +2470,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev, #endif /* fs/char_dev.c */ -#define CHRDEV_MAJOR_HASH_SIZE 255 +#define CHRDEV_MAJOR_MAX 512 /* Marks the bottom of the first segment of free char majors */ #define CHRDEV_MAJOR_DYN_END 234 /* Marks the top and bottom of the second segment of free char majors */