use mutex instead of semaphore for misc char devices (0e82d5b6) · Commits · 戴 / test

drivers/char/misc.c

+14 −13

Original line number	Diff line number	Diff line
		@@ -41,6 +41,7 @@
		#include <linux/kernel.h>
		#include <linux/major.h>
		#include <linux/slab.h>
		#include <linux/mutex.h>
		#include <linux/proc_fs.h>
		#include <linux/seq_file.h>
		#include <linux/stat.h>
		@@ -53,7 +54,7 @@
		* Head entry for the doubly linked miscdevice list
		*/
		static LIST_HEAD(misc_list);
		static DECLARE_MUTEX(misc_sem);
		static DEFINE_MUTEX(misc_mtx);

		/*
		* Assigned numbers, used for dynamic minors
		@@ -69,7 +70,7 @@ static void misc_seq_start(struct seq_file seq, loff_t *pos)
		struct miscdevice *p;
		loff_t off = 0;

		down(&misc_sem);
		mutex_lock(&misc_mtx);
		list_for_each_entry(p, &misc_list, list) {
		if (*pos == off++)
		return p;
		@@ -89,7 +90,7 @@ static void misc_seq_next(struct seq_file seq, void v, loff_t pos)

		static void misc_seq_stop(struct seq_file seq, void v)
		{
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		}

		static int misc_seq_show(struct seq_file seq, void v)
		@@ -129,7 +130,7 @@ static int misc_open(struct inode * inode, struct file * file)
		int err = -ENODEV;
		const struct file_operations old_fops, new_fops = NULL;

		down(&misc_sem);
		mutex_lock(&misc_mtx);

		list_for_each_entry(c, &misc_list, list) {
		if (c->minor == minor) {
		@@ -139,9 +140,9 @@ static int misc_open(struct inode * inode, struct file * file)
		}

		if (!new_fops) {
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		request_module("char-major-%d-%d", MISC_MAJOR, minor);
		down(&misc_sem);
		mutex_lock(&misc_mtx);

		list_for_each_entry(c, &misc_list, list) {
		if (c->minor == minor) {
		@@ -165,7 +166,7 @@ static int misc_open(struct inode * inode, struct file * file)
		}
		fops_put(old_fops);
		fail:
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		return err;
		}

		@@ -201,10 +202,10 @@ int misc_register(struct miscdevice * misc)

		INIT_LIST_HEAD(&misc->list);

		down(&misc_sem);
		mutex_lock(&misc_mtx);
		list_for_each_entry(c, &misc_list, list) {
		if (c->minor == misc->minor) {
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		return -EBUSY;
		}
		}
		@@ -215,7 +216,7 @@ int misc_register(struct miscdevice * misc)
		if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
		break;
		if (i<0) {
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		return -EBUSY;
		}
		misc->minor = i;
		@@ -238,7 +239,7 @@ int misc_register(struct miscdevice * misc)
		*/
		list_add(&misc->list, &misc_list);
		out:
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		return err;
		}

		@@ -259,13 +260,13 @@ int misc_deregister(struct miscdevice * misc)
		if (list_empty(&misc->list))
		return -EINVAL;

		down(&misc_sem);
		mutex_lock(&misc_mtx);
		list_del(&misc->list);
		device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
		if (i < DYNAMIC_MINORS && i>0) {
		misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
		}
		up(&misc_sem);
		mutex_unlock(&misc_mtx);
		return 0;
		}

Admin message