Commit 575cfc67 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by Jens Axboe
Browse files

floppy: use atomic type for usage_count 



The usage_count was being protected by a lock which was only there to
create an atomic counter.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 41a55b4d

drivers/block/floppy.c

+12 −30
Original line number Diff line number Diff line
@@ -578,7 +578,7 @@ static void reset_fdc(void); 
#define NEED_1_RECAL	-2

#define NEED_2_RECAL	-3



static int usage_count;

static atomic_t usage_count = ATOMIC_INIT(0);



/* buffer related variables */

static int buffer_track = -1;
@@ -860,7 +860,7 @@ static void set_fdc(int drive) 
/* locks the driver */

static int _lock_fdc(int drive, bool interruptible, int line)

{

	if (!usage_count) {

	if (atomic_read(&usage_count) == 0) {

		pr_err("Trying to lock fdc while usage count=0 at line %d\n",

		       line);

		return -1;
@@ -2941,7 +2941,7 @@ static void do_fd_request(struct request_queue *q) 
		return;

	}



	if (usage_count == 0) {

	if (atomic_read(&usage_count) == 0) {

		pr_info("warning: usage count=0, current_req=%p exiting\n",

			current_req);

		pr_info("sect=%ld type=%x flags=%x\n",
@@ -3858,7 +3858,7 @@ static int floppy_revalidate(struct gendisk *disk) 
	if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags) ||

	    test_bit(FD_VERIFY_BIT, &UDRS->flags) ||

	    test_bit(drive, &fake_change) || NO_GEOM) {

		if (usage_count == 0) {

		if (atomic_read(&usage_count) == 0) {

			pr_info("VFS: revalidate called on non-open device.\n");

			return -EFAULT;

		}
@@ -4357,7 +4357,7 @@ static int __init floppy_init(void) 
	platform_device_unregister(&floppy_device[drive]);

out_flush_work:

	flush_scheduled_work();

	if (usage_count)

	if (atomic_read(&usage_count))

		floppy_release_irq_and_dma();

out_unreg_region:

	blk_unregister_region(MKDEV(FLOPPY_MAJOR, 0), 256);
@@ -4374,8 +4374,6 @@ static int __init floppy_init(void) 
	return err;

}



static DEFINE_SPINLOCK(floppy_usage_lock);



static const struct io_region {

	int offset;

	int size;
@@ -4421,14 +4419,8 @@ static void floppy_release_regions(int fdc) 


static int floppy_grab_irq_and_dma(void)

{

	unsigned long flags;



	spin_lock_irqsave(&floppy_usage_lock, flags);

	if (usage_count++) {

		spin_unlock_irqrestore(&floppy_usage_lock, flags);

	if (atomic_inc_return(&usage_count) > 1)

		return 0;

	}

	spin_unlock_irqrestore(&floppy_usage_lock, flags);



	/*

	 * We might have scheduled a free_irq(), wait it to
@@ -4439,9 +4431,7 @@ static int floppy_grab_irq_and_dma(void) 
	if (fd_request_irq()) {

		DPRINT("Unable to grab IRQ%d for the floppy driver\n",

		       FLOPPY_IRQ);

		spin_lock_irqsave(&floppy_usage_lock, flags);

		usage_count--;

		spin_unlock_irqrestore(&floppy_usage_lock, flags);

		atomic_dec(&usage_count);

		return -1;

	}

	if (fd_request_dma()) {
@@ -4451,9 +4441,7 @@ static int floppy_grab_irq_and_dma(void) 
			use_virtual_dma = can_use_virtual_dma = 1;

		if (!(can_use_virtual_dma & 1)) {

			fd_free_irq();

			spin_lock_irqsave(&floppy_usage_lock, flags);

			usage_count--;

			spin_unlock_irqrestore(&floppy_usage_lock, flags);

			atomic_dec(&usage_count);

			return -1;

		}

	}
@@ -4488,9 +4476,7 @@ static int floppy_grab_irq_and_dma(void) 
	fd_free_dma();

	while (--fdc >= 0)

		floppy_release_regions(fdc);

	spin_lock_irqsave(&floppy_usage_lock, flags);

	usage_count--;

	spin_unlock_irqrestore(&floppy_usage_lock, flags);

	atomic_dec(&usage_count);

	return -1;

}
@@ -4502,14 +4488,10 @@ static void floppy_release_irq_and_dma(void) 
#endif

	long tmpsize;

	unsigned long tmpaddr;

	unsigned long flags;



	spin_lock_irqsave(&floppy_usage_lock, flags);

	if (--usage_count) {

		spin_unlock_irqrestore(&floppy_usage_lock, flags);

	if (!atomic_dec_and_test(&usage_count))

		return;

	}

	spin_unlock_irqrestore(&floppy_usage_lock, flags);



	if (irqdma_allocated) {

		fd_disable_dma();

		fd_free_dma();
@@ -4602,7 +4584,7 @@ static void __exit floppy_module_exit(void) 
	del_timer_sync(&fd_timer);

	blk_cleanup_queue(floppy_queue);



	if (usage_count)

	if (atomic_read(&usage_count))

		floppy_release_irq_and_dma();



	/* eject disk, if any */