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floppy: use atomic type for usage_count

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

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Stephen Hemminger 2010-06-15 13:21:11 +02:00 committed by Jens Axboe
parent 41a55b4de3
commit 575cfc673e
1 changed files with 12 additions and 30 deletions
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42
drivers/block/floppy.c
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@ -578,7 +578,7 @@ static void reset_fdc(void);
#define NEED_1_RECAL -2 #define NEED_1_RECAL -2
#define NEED_2_RECAL -3 #define NEED_2_RECAL -3
static int usage_count; static atomic_t usage_count = ATOMIC_INIT(0);
/* buffer related variables */ /* buffer related variables */
static int buffer_track = -1; static int buffer_track = -1;
@ -860,7 +860,7 @@ static void set_fdc(int drive)
/* locks the driver */ /* locks the driver */
static int _lock_fdc(int drive, bool interruptible, int line) 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", pr_err("Trying to lock fdc while usage count=0 at line %d\n",
line); line);
return -1; return -1;
@ -2941,7 +2941,7 @@ static void do_fd_request(struct request_queue *q)
return; return;
} }
if (usage_count == 0) { if (atomic_read(&usage_count) == 0) {
pr_info("warning: usage count=0, current_req=%p exiting\n", pr_info("warning: usage count=0, current_req=%p exiting\n",
current_req); current_req);
pr_info("sect=%ld type=%x flags=%x\n", 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) || if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags) ||
test_bit(FD_VERIFY_BIT, &UDRS->flags) || test_bit(FD_VERIFY_BIT, &UDRS->flags) ||
test_bit(drive, &fake_change) || NO_GEOM) { 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"); pr_info("VFS: revalidate called on non-open device.\n");
return -EFAULT; return -EFAULT;
} }
@ -4357,7 +4357,7 @@ out_unreg_platform_dev:
platform_device_unregister(&floppy_device[drive]); platform_device_unregister(&floppy_device[drive]);
out_flush_work: out_flush_work:
flush_scheduled_work(); flush_scheduled_work();
if (usage_count) if (atomic_read(&usage_count))
floppy_release_irq_and_dma(); floppy_release_irq_and_dma();
out_unreg_region: out_unreg_region:
blk_unregister_region(MKDEV(FLOPPY_MAJOR, 0), 256); blk_unregister_region(MKDEV(FLOPPY_MAJOR, 0), 256);
@ -4374,8 +4374,6 @@ out_put_disk:
return err; return err;
} }
static DEFINE_SPINLOCK(floppy_usage_lock);
static const struct io_region { static const struct io_region {
int offset; int offset;
int size; int size;
@ -4421,14 +4419,8 @@ static void floppy_release_regions(int fdc)
static int floppy_grab_irq_and_dma(void) static int floppy_grab_irq_and_dma(void)
{ {
unsigned long flags; if (atomic_inc_return(&usage_count) > 1)
spin_lock_irqsave(&floppy_usage_lock, flags);
if (usage_count++) {
spin_unlock_irqrestore(&floppy_usage_lock, flags);
return 0; return 0;
}
spin_unlock_irqrestore(&floppy_usage_lock, flags);
/* /*
* We might have scheduled a free_irq(), wait it to * 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()) { if (fd_request_irq()) {
DPRINT("Unable to grab IRQ%d for the floppy driver\n", DPRINT("Unable to grab IRQ%d for the floppy driver\n",
FLOPPY_IRQ); FLOPPY_IRQ);
spin_lock_irqsave(&floppy_usage_lock, flags); atomic_dec(&usage_count);
usage_count--;
spin_unlock_irqrestore(&floppy_usage_lock, flags);
return -1; return -1;
} }
if (fd_request_dma()) { if (fd_request_dma()) {
@ -4451,9 +4441,7 @@ static int floppy_grab_irq_and_dma(void)
use_virtual_dma = can_use_virtual_dma = 1; use_virtual_dma = can_use_virtual_dma = 1;
if (!(can_use_virtual_dma & 1)) { if (!(can_use_virtual_dma & 1)) {
fd_free_irq(); fd_free_irq();
spin_lock_irqsave(&floppy_usage_lock, flags); atomic_dec(&usage_count);
usage_count--;
spin_unlock_irqrestore(&floppy_usage_lock, flags);
return -1; return -1;
} }
} }
@ -4488,9 +4476,7 @@ cleanup:
fd_free_dma(); fd_free_dma();
while (--fdc >= 0) while (--fdc >= 0)
floppy_release_regions(fdc); floppy_release_regions(fdc);
spin_lock_irqsave(&floppy_usage_lock, flags); atomic_dec(&usage_count);
usage_count--;
spin_unlock_irqrestore(&floppy_usage_lock, flags);
return -1; return -1;
} }
@ -4502,14 +4488,10 @@ static void floppy_release_irq_and_dma(void)
#endif #endif
long tmpsize; long tmpsize;
unsigned long tmpaddr; unsigned long tmpaddr;
unsigned long flags;
spin_lock_irqsave(&floppy_usage_lock, flags); if (!atomic_dec_and_test(&usage_count))
if (--usage_count) {
spin_unlock_irqrestore(&floppy_usage_lock, flags);
return; return;
}
spin_unlock_irqrestore(&floppy_usage_lock, flags);
if (irqdma_allocated) { if (irqdma_allocated) {
fd_disable_dma(); fd_disable_dma();
fd_free_dma(); fd_free_dma();
@ -4602,7 +4584,7 @@ static void __exit floppy_module_exit(void)
del_timer_sync(&fd_timer); del_timer_sync(&fd_timer);
blk_cleanup_queue(floppy_queue); blk_cleanup_queue(floppy_queue);
if (usage_count) if (atomic_read(&usage_count))
floppy_release_irq_and_dma(); floppy_release_irq_and_dma();
/* eject disk, if any */ /* eject disk, if any */