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authorAlexander Gordeev <lasaine@lvk.cs.msu.su>2011-01-12 17:00:53 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 08:03:20 -0800
commit2a5cd6e2fb1984cc83f08b3645bf394830ac7825 (patch)
tree14082324f971c3d8af26840caf9d68a4524269b7 /drivers/pps
parent083e58666ff5b3c5750d9a5c0560018b03cfb4b2 (diff)
downloadlinux-2a5cd6e2fb1984cc83f08b3645bf394830ac7825.tar.bz2
pps: make idr lock a mutex and protect idr_pre_get
Now pps_idr_lock is never used in interrupt context so we can replace spin_lock_irq/spin_unlock_irq with plain spin_lock/spin_unlock. But there is also a potential race condition when someone can steal an id which was allocated by idr_pre_get before it is used. So convert spin lock to mutex and protect the whole id generation process. Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su> Cc: Rodolfo Giometti <giometti@linux.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/pps')
-rw-r--r--drivers/pps/pps.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 79b445578132..9e15cf1da946 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -27,6 +27,7 @@
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/idr.h>
+#include <linux/mutex.h>
#include <linux/cdev.h>
#include <linux/poll.h>
#include <linux/pps_kernel.h>
@@ -39,7 +40,7 @@
static dev_t pps_devt;
static struct class *pps_class;
-static DEFINE_SPINLOCK(pps_idr_lock);
+static DEFINE_MUTEX(pps_idr_lock);
static DEFINE_IDR(pps_idr);
/*
@@ -239,9 +240,9 @@ static void pps_device_destruct(struct device *dev)
/* release id here to protect others from using it while it's
* still in use */
- spin_lock_irq(&pps_idr_lock);
+ mutex_lock(&pps_idr_lock);
idr_remove(&pps_idr, pps->id);
- spin_unlock_irq(&pps_idr_lock);
+ mutex_unlock(&pps_idr_lock);
kfree(dev);
kfree(pps);
@@ -252,17 +253,19 @@ int pps_register_cdev(struct pps_device *pps)
int err;
dev_t devt;
+ mutex_lock(&pps_idr_lock);
/* Get new ID for the new PPS source */
- if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0)
+ if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
+ mutex_unlock(&pps_idr_lock);
return -ENOMEM;
+ }
/* Now really allocate the PPS source.
* After idr_get_new() calling the new source will be freely available
* into the kernel.
*/
- spin_lock_irq(&pps_idr_lock);
err = idr_get_new(&pps_idr, pps, &pps->id);
- spin_unlock_irq(&pps_idr_lock);
+ mutex_unlock(&pps_idr_lock);
if (err < 0)
return err;
@@ -302,9 +305,9 @@ del_cdev:
cdev_del(&pps->cdev);
free_idr:
- spin_lock_irq(&pps_idr_lock);
+ mutex_lock(&pps_idr_lock);
idr_remove(&pps_idr, pps->id);
- spin_unlock_irq(&pps_idr_lock);
+ mutex_unlock(&pps_idr_lock);
return err;
}