The patch titled
floppy: use atomic type for usage_count
has been added to the -mm tree. Its filename is
floppy-use-atomic-type-for-usage_count.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: floppy: use atomic type for usage_count
From: Stephen Hemminger <shemminger@xxxxxxxxxx>
The usage_count was being protected by a lock which was only there to
create an atomic counter.
Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/floppy.c | 42 +++++++++++----------------------------
1 file changed, 12 insertions(+), 30 deletions(-)
diff -puN drivers/block/floppy.c~floppy-use-atomic-type-for-usage_count drivers/block/floppy.c
--- a/drivers/block/floppy.c~floppy-use-atomic-type-for-usage_count
+++ a/drivers/block/floppy.c
@@ -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
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 gend
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 @@ out_unreg_platform_dev:
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 @@ out_put_disk:
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 f
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 @@ cleanup:
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(v
#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(vo
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 */
_
Patches currently in -mm which might be from shemminger@xxxxxxxxxx are
linux-next.patch
floppy-initialize-debug-jiffies-offset.patch
floppy-remove-unnecessary-inlines.patch
floppy-silence-warning-during-disk-test.patch
floppy-use-atomic-type-for-usage_count.patch
floppy-cmos-attribute-should-be-static.patch
floppy-fix-signed-unsigned-warnings.patch
floppy-use-wait_event_interruptible.patch
floppy-use-warning-macros.patch
floppy-make-controller-const.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
