The patch titled
pps: make idr lock a mutex and protect idr_pre_get
has been added to the -mm tree. Its filename is
pps-make-idr-lock-a-mutex-and-protect-idr_pre_get.patch
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------------------------------------------------------
Subject: pps: make idr lock a mutex and protect idr_pre_get
From: Alexander Gordeev <lasaine@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Cc: Rodolfo Giometti <giometti@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/pps/pps.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff -puN drivers/pps/pps.c~pps-make-idr-lock-a-mutex-and-protect-idr_pre_get drivers/pps/pps.c
--- a/drivers/pps/pps.c~pps-make-idr-lock-a-mutex-and-protect-idr_pre_get
+++ a/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 d
/* 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
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;
}
_
Patches currently in -mm which might be from lasaine@xxxxxxxxxxxxx are
pps-trivial-fixes.patch
pps-declare-variables-where-they-are-used-in-switch.patch
pps-fix-race-in-pps_fetch-handler.patch
pps-unify-timestamp-gathering.patch
pps-access-pps-device-by-direct-pointer.patch
pps-convert-printk-pr_-to-dev_.patch
pps-move-idr-stuff-to-ppsc.patch
pps-make-idr-lock-a-mutex-and-protect-idr_pre_get.patch
pps-do-not-disable-interrupts-for-idr-operations.patch
pps-use-bug_on-for-kernel-api-safety-checks.patch
pps-simplify-conditions-a-bit.patch
pps-timestamp-is-always-passed-to-dcd_change.patch
ntp-add-hardpps-implementation.patch
pps-capture-monotonic_raw-timestamps-as-well.patch
pps-add-kernel-consumer-support.patch
pps-add-parallel-port-pps-client.patch
pps-add-parallel-port-pps-signal-generator.patch
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