Message ID | 200809222151.m8MLp3tb031906@imap1.linux-foundation.org |
---|---|
State | Accepted, archived |
Delegated to: | David Miller |
Headers | show |
From: akpm@linux-foundation.org Date: Mon, 22 Sep 2008 14:51:03 -0700 > - Remove noop VFS stubs. The VFS does that on a NULL pointer anyways. > - Fix timer handler prototype to be correct > - Comment ugly SMP race I didn't fix. > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Applied to net-next-2.6 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Sep 22, 2008 at 07:18:26PM -0700, David Miller wrote: > From: akpm@linux-foundation.org > Date: Mon, 22 Sep 2008 14:51:03 -0700 > > > - Remove noop VFS stubs. The VFS does that on a NULL pointer anyways. > > - Fix timer handler prototype to be correct > > - Comment ugly SMP race I didn't fix. > > > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > > Applied to net-next-2.6 I'm hoping someone takes care of the SMP race. I think the timers need all reference counting similar to other network objects to handle this cleanly. It might be a good idea to mark it BROKEN_ON_SMP in the meantime. -Andi
On Tue, Sep 23, 2008 at 04:27:32AM +0200, Andi Kleen wrote: > On Mon, Sep 22, 2008 at 07:18:26PM -0700, David Miller wrote: > > From: akpm@linux-foundation.org > > Date: Mon, 22 Sep 2008 14:51:03 -0700 > > > > > - Remove noop VFS stubs. The VFS does that on a NULL pointer anyways. > > > - Fix timer handler prototype to be correct > > > - Comment ugly SMP race I didn't fix. > > > > > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > > > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > > > > Applied to net-next-2.6 > > I'm hoping someone takes care of the SMP race. I think the timers > need all reference counting similar to other network objects to > handle this cleanly. Yes I already have some idea without refcounting, checking how much time is left if it is more as some treshhold (maybe 2 or 10 jiffies) delete the timer, if not mark it for deletion only and delete it during the run function without triggering the device. In the race case it would trigger the device too but this is not critical. Another easier implementation could mark it only, without trying to delete it imediately. But in this case unneeded timers would hang around (on big busy PBX boxes this can be some 100) for some time. What do you think ? > > It might be a good idea to mark it BROKEN_ON_SMP in the meantime. No really needed, normally the timers deleted long time before running out or never so it should never see such a race, maybe if the application is aborted and cleanup all timers this could happen but also this should be no normal case, since usually you do not kill a PBX if any connections are active. Yes it could be used to do some deny on service kind of attack, so it should be fixed at all.
On Mon, Sep 22, 2008 at 02:51:03PM -0700, akpm@linux-foundation.org wrote: > From: Andi Kleen <andi@firstfloor.org> > > - Remove noop VFS stubs. The VFS does that on a NULL pointer anyways. > -static loff_t > -mISDN_llseek(struct file *filep, loff_t offset, int orig) > -{ > - return -ESPIPE; > -} > static struct file_operations mISDN_fops = { > - .llseek = mISDN_llseek, This is wrong. no llseek means we use default_llseek, which is different from returning -ESPIPE. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Sep 23, 2008 at 08:34:07AM +0200, Karsten Keil wrote: > No really needed, normally the timers deleted long time before running out > or never so it should never see such a race, maybe if the application is > aborted and cleanup all timers this could happen but also this should be no > normal case, since usually you do not kill a PBX if any connections are > active. > Yes it could be used to do some deny on service kind of attack, so it should > be fixed at all. All these timers are completely user controller and non-prviliegued. So this _is_ a serious issue. In fact I think we should just rip out this whole module, it's a really useless duplicate timer interface. Gotta love merging unreviewed code. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Sep 23, 2008 at 06:40:26AM -0400, Christoph Hellwig wrote: > On Mon, Sep 22, 2008 at 02:51:03PM -0700, akpm@linux-foundation.org wrote: > > From: Andi Kleen <andi@firstfloor.org> > > > > - Remove noop VFS stubs. The VFS does that on a NULL pointer anyways. > > > -static loff_t > > -mISDN_llseek(struct file *filep, loff_t offset, int orig) > > -{ > > - return -ESPIPE; > > -} > > > static struct file_operations mISDN_fops = { > > - .llseek = mISDN_llseek, > > This is wrong. no llseek means we use default_llseek, which is > different from returning -ESPIPE. No it's correct. Character devices don't have FMODE_LSEEK set and then no_llseek is the default fallback. -Andi
diff -puN drivers/isdn/mISDN/timerdev.c~misdn-misc-timerdev-fixes drivers/isdn/mISDN/timerdev.c --- a/drivers/isdn/mISDN/timerdev.c~misdn-misc-timerdev-fixes +++ a/drivers/isdn/mISDN/timerdev.c @@ -124,18 +124,6 @@ mISDN_read(struct file *filep, char *buf return ret; } -static loff_t -mISDN_llseek(struct file *filep, loff_t offset, int orig) -{ - return -ESPIPE; -} - -static ssize_t -mISDN_write(struct file *filep, const char *buf, size_t count, loff_t *off) -{ - return -EOPNOTSUPP; -} - static unsigned int mISDN_poll(struct file *filep, poll_table *wait) { @@ -157,8 +145,9 @@ mISDN_poll(struct file *filep, poll_tabl } static void -dev_expire_timer(struct mISDNtimer *timer) +dev_expire_timer(unsigned long data) { + struct mISDNtimer *timer = (void *)data; u_long flags; spin_lock_irqsave(&timer->dev->lock, flags); @@ -191,7 +180,7 @@ misdn_add_timer(struct mISDNtimerdev *de spin_unlock_irqrestore(&dev->lock, flags); timer->dev = dev; timer->tl.data = (long)timer; - timer->tl.function = (void *) dev_expire_timer; + timer->tl.function = dev_expire_timer; init_timer(&timer->tl); timer->tl.expires = jiffies + ((HZ * (u_long)timeout) / 1000); add_timer(&timer->tl); @@ -211,6 +200,9 @@ misdn_del_timer(struct mISDNtimerdev *de list_for_each_entry(timer, &dev->pending, list) { if (timer->id == id) { list_del_init(&timer->list); + /* RED-PEN AK: race -- timer can be still running on + * other CPU. Needs reference count I think + */ del_timer(&timer->tl); ret = timer->id; kfree(timer); @@ -268,9 +260,7 @@ mISDN_ioctl(struct inode *inode, struct } static struct file_operations mISDN_fops = { - .llseek = mISDN_llseek, .read = mISDN_read, - .write = mISDN_write, .poll = mISDN_poll, .ioctl = mISDN_ioctl, .open = mISDN_open,