net: Remove BKL from tun (deed49fb) · Commits · 戴 / test

The lock_kernel/unlock_kernel() in cycle_kernel_lock() which is called in tun_chr_open() is not serializing against anything and safe to remove. tun_chr_fasync() is serialized by get/put_tun() and fasync_helper() has no dependency on BKL. The modification of tun->flags is racy with and without the BKL so removing it does not make it worse. Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/tun.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -44,7 +44,6 @@
		#include <linux/kernel.h>
		#include <linux/major.h>
		#include <linux/slab.h>
		#include <linux/smp_lock.h>
		#include <linux/poll.h>
		#include <linux/fcntl.h>
		#include <linux/init.h>
		@@ -1285,7 +1284,6 @@ static int tun_chr_fasync(int fd, struct file *file, int on)

		DBG(KERN_INFO "%s: tun_chr_fasync %d\n", tun->dev->name, on);

		lock_kernel();
		if ((ret = fasync_helper(fd, file, on, &tun->fasync)) < 0)
		goto out;

		@@ -1298,7 +1296,6 @@ static int tun_chr_fasync(int fd, struct file *file, int on)
		tun->flags &= ~TUN_FASYNC;
		ret = 0;
		out:
		unlock_kernel();
		tun_put(tun);
		return ret;
		}
		@@ -1306,7 +1303,7 @@ out:
		static int tun_chr_open(struct inode inode, struct file file)
		{
		struct tun_file *tfile;
		cycle_kernel_lock();

		DBG1(KERN_INFO "tunX: tun_chr_open\n");

		tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);

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