Commit 7a9cc6e1 authored by Michael Holzheu's avatar Michael Holzheu Committed by Martin Schwidefsky
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s390/cio: Make /dev/chsc a single-open device 



In order to allow serialization of dynamic I/O with this patch
the /dev/chsc character device can only be accessed by one
single opener. Any subsequent open calls are rejected with EBUSY.

Signed-off-by: default avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 64150adf

drivers/s390/cio/chsc_sch.c

+19 −1
Original line number Diff line number Diff line
@@ -847,9 +847,27 @@ static long chsc_ioctl(struct file *filp, unsigned int cmd, 
	}

}



static atomic_t chsc_ready_for_use = ATOMIC_INIT(1);



static int chsc_open(struct inode *inode, struct file *file)

{

	if (!atomic_dec_and_test(&chsc_ready_for_use)) {

		atomic_inc(&chsc_ready_for_use);

		return -EBUSY;

	}

	return nonseekable_open(inode, file);

}



static int chsc_release(struct inode *inode, struct file *filp)

{

	atomic_inc(&chsc_ready_for_use);

	return 0;

}



static const struct file_operations chsc_fops = {

	.owner = THIS_MODULE,

	.open = nonseekable_open,

	.open = chsc_open,

	.release = chsc_release,

	.unlocked_ioctl = chsc_ioctl,

	.compat_ioctl = chsc_ioctl,

	.llseek = no_llseek,