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staging: dgnc: take a lock when storing value in dgnc_poll_tick

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Reads of dgnc_poll_tick are protected by dgnc_poll_lock spinlock, but the write
to dgnc_poll_tick is not. It could theoretically race.

Signed-off-by: Salah Triki <salah.triki@acm.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Salah Triki 2015-10-04 02:49:48 +01:00 committed by Greg Kroah-Hartman
parent 6d99d6a3cf
commit 51abf45c23
3 changed files with 10 additions and 2 deletions
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2
drivers/staging/dgnc/dgnc_driver.c
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@ -63,6 +63,7 @@ static const struct file_operations dgnc_BoardFops = {
uint dgnc_NumBoards;
struct dgnc_board *dgnc_Board[MAXBOARDS];
DEFINE_SPINLOCK(dgnc_global_lock);
DEFINE_SPINLOCK(dgnc_poll_lock); /* Poll scheduling lock */
uint dgnc_Major;
int dgnc_poll_tick = 20; /* Poll interval - 20 ms */
@ -74,7 +75,6 @@ static struct class *dgnc_class;
/*
* Poller stuff
*/
static DEFINE_SPINLOCK(dgnc_poll_lock); /* Poll scheduling lock */
static ulong dgnc_poll_time; /* Time of next poll */
static uint dgnc_poll_stop; /* Used to tell poller to stop */
static struct timer_list dgnc_poll_timer;

1
drivers/staging/dgnc/dgnc_driver.h
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@ -390,6 +390,7 @@ struct channel_t {
extern uint dgnc_Major; /* Our driver/mgmt major */
extern int dgnc_poll_tick; /* Poll interval - 20 ms */
extern spinlock_t dgnc_global_lock; /* Driver global spinlock */
extern spinlock_t dgnc_poll_lock; /* Poll scheduling lock */
extern uint dgnc_NumBoards; /* Total number of boards */
extern struct dgnc_board *dgnc_Board[MAXBOARDS]; /* Array of board structs */

9
drivers/staging/dgnc/dgnc_sysfs.c
View File

@ -56,11 +56,18 @@ static ssize_t dgnc_driver_pollrate_show(struct device_driver *ddp, char *buf)
static ssize_t dgnc_driver_pollrate_store(struct device_driver *ddp,
const char *buf, size_t count)
{
unsigned long flags;
int tick;
int ret;
ret = sscanf(buf, "%d\n", &dgnc_poll_tick);
ret = sscanf(buf, "%d\n", &tick);
if (ret != 1)
return -EINVAL;
spin_lock_irqsave(&dgnc_poll_lock, flags);
dgnc_poll_tick = tick;
spin_unlock_irqrestore(&dgnc_poll_lock, flags);
return count;
}
static DRIVER_ATTR(pollrate, (S_IRUSR | S_IWUSR), dgnc_driver_pollrate_show,