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Commit 10963ea1 authored by Stefan Richter's avatar Stefan Richter
Browse files

ieee1394: raw1394: replace BKL by local mutex, make ioctl() and mmap() thread-safe 



This removes the last usage of the Big Kernel Lock from the ieee1394
stack, i.e. from raw1394's (unlocked_)ioctl and compat_ioctl.

The ioctl()s don't need to take the BKL, but they need to be serialized
per struct file *.  In particular, accesses to ->iso_state need to be
serial.  We simply use a blocking mutex for this purpose because
libraw1394 does not use O_NONBLOCK.  In practice, there is no lock
contention anyway because most if not all libraw1394 clients use a
libraw1394 handle only in a single thread.

mmap() also accesses ->iso_state.  Until now this was unprotected
against concurrent changes by ioctls.  Fix this bug while we are at it.

Signed-off-by: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
parent ed6ffd08

drivers/ieee1394/raw1394-private.h

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ enum raw1394_iso_state { RAW1394_ISO_INACTIVE = 0, 
struct file_info {

        struct list_head list;



	struct mutex state_mutex;

        enum { opened, initialized, connected } state;

        unsigned int protocol_version;

drivers/ieee1394/raw1394.c

+17 −6
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/fs.h>

#include <linux/poll.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/init.h>

#include <linux/interrupt.h>

#include <linux/vmalloc.h>
@@ -2541,11 +2542,18 @@ static int raw1394_read_cycle_timer(struct file_info *fi, void __user * uaddr) 
static int raw1394_mmap(struct file *file, struct vm_area_struct *vma)

{

	struct file_info *fi = file->private_data;

	int ret;



	mutex_lock(&fi->state_mutex);



	if (fi->iso_state == RAW1394_ISO_INACTIVE)

		return -EINVAL;

		ret = -EINVAL;

	else

		ret = dma_region_mmap(&fi->iso_handle->data_buf, file, vma);



	mutex_unlock(&fi->state_mutex);



	return dma_region_mmap(&fi->iso_handle->data_buf, file, vma);

	return ret;

}



/* ioctl is only used for rawiso operations */
@@ -2659,10 +2667,12 @@ static long do_raw1394_ioctl(struct file *file, unsigned int cmd, 
static long raw1394_ioctl(struct file *file, unsigned int cmd,

							unsigned long arg)

{

	struct file_info *fi = file->private_data;

	long ret;

	lock_kernel();



	mutex_lock(&fi->state_mutex);

	ret = do_raw1394_ioctl(file, cmd, arg);

	unlock_kernel();

	mutex_unlock(&fi->state_mutex);

	return ret;

}
@@ -2724,7 +2734,7 @@ static long raw1394_compat_ioctl(struct file *file, 
	void __user *argp = (void __user *)arg;

	long err;



	lock_kernel();

	mutex_lock(&fi->state_mutex);

	switch (cmd) {

	/* These requests have same format as long as 'int' has same size. */

	case RAW1394_IOC_ISO_RECV_INIT:
@@ -2757,7 +2767,7 @@ static long raw1394_compat_ioctl(struct file *file, 
		err = -EINVAL;

		break;

	}

	unlock_kernel();

	mutex_unlock(&fi->state_mutex);



	return err;

}
@@ -2791,6 +2801,7 @@ static int raw1394_open(struct inode *inode, struct file *file) 
	fi->notification = (u8) RAW1394_NOTIFY_ON;	/* busreset notification */



	INIT_LIST_HEAD(&fi->list);

	mutex_init(&fi->state_mutex);

	fi->state = opened;

	INIT_LIST_HEAD(&fi->req_pending);

	INIT_LIST_HEAD(&fi->req_complete);