Re: [patch 00/16] timers: Plug debugobject leaks and use del_timer_sync() in exit/teardown

[Thomas Gleixner]

On Sun, 23 Mar 2014, Julia Lawall wrote:
> diff -u -p a/arch/mips/lasat/picvue_proc.c b/arch/mips/lasat/picvue_proc.c
> --- a/arch/mips/lasat/picvue_proc.c
> +++ b/arch/mips/lasat/picvue_proc.c
> @@ -175,7 +175,7 @@ static void pvc_proc_cleanup(void)
>  	remove_proc_entry("scroll", pvc_display_dir);
>  	remove_proc_entry(DISPLAY_DIR_NAME, NULL);
>  
> -	del_timer(&timer);
> +	del_timer_sync(&timer);

Correct.

>  }
>  
>  static int __init pvc_proc_init(void)
> diff -u -p a/drivers/tty/serial/mux.c b/drivers/tty/serial/mux.c
> --- a/drivers/tty/serial/mux.c
> +++ b/drivers/tty/serial/mux.c
> @@ -613,7 +613,7 @@ static void __exit mux_exit(void)
>  {
>  	/* Delete the Mux timer. */
>  	if(port_cnt > 0) {
> -		del_timer(&mux_timer);
> +		del_timer_sync(&mux_timer);

Correct.

>  #ifdef CONFIG_SERIAL_MUX_CONSOLE
>  		unregister_console(&mux_console);
>  #endif
> diff -u -p a/drivers/input/serio/hp_sdc.c b/drivers/input/serio/hp_sdc.c
> --- a/drivers/input/serio/hp_sdc.c
> +++ b/drivers/input/serio/hp_sdc.c
> @@ -984,7 +984,7 @@ static void hp_sdc_exit(void)
>  	free_irq(hp_sdc.irq, &hp_sdc);
>  	write_unlock_irq(&hp_sdc.lock);
>  
> -	del_timer(&hp_sdc.kicker);
> +	del_timer_sync(&hp_sdc.kicker);

Correct.
  
>  	tasklet_kill(&hp_sdc.task);
>  
> diff -u -p a/drivers/isdn/sc/init.c b/drivers/isdn/sc/init.c
> --- a/drivers/isdn/sc/init.c
> +++ b/drivers/isdn/sc/init.c
> @@ -390,8 +390,8 @@ static void __exit sc_exit(void)
>  		/*
>  		 * kill the timers
>  		 */
> -		del_timer(&(sc_adapter[i]->reset_timer));
> -		del_timer(&(sc_adapter[i]->stat_timer));
> +		del_timer_sync(&(sc_adapter[i]->reset_timer));
> +		del_timer_sync(&(sc_adapter[i]->stat_timer));

Correct.
  
>  		/*
>  		 * Tell I4L we're toast
> diff -u -p a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
> --- a/drivers/isdn/i4l/isdn_common.c
> +++ b/drivers/isdn/i4l/isdn_common.c
> @@ -2381,7 +2381,7 @@ static void __exit isdn_exit(void)
>  	}
>  	isdn_tty_exit();
>  	unregister_chrdev(ISDN_MAJOR, "isdn");
> -	del_timer(&dev->timer);
> +	del_timer_sync(&dev->timer);

Correct.

>  	/* call vfree with interrupts enabled, else it will hang */
>  	vfree(dev);
>  	printk(KERN_NOTICE "ISDN-subsystem unloaded\n");
> diff -u -p a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/mISDN/hfcpci.c
> --- a/drivers/isdn/hardware/mISDN/hfcpci.c
> +++ b/drivers/isdn/hardware/mISDN/hfcpci.c
> @@ -2352,7 +2352,7 @@ static void __exit
>  HFC_cleanup(void)
>  {
>  	if (timer_pending(&hfc_tl))
> -		del_timer(&hfc_tl);
> +		del_timer_sync(&hfc_tl);

That's incomplete the timer_pending() check is racy as well and the
timer is rearming itself from the callback.
  
>  	pci_unregister_driver(&hfc_driver);
>  }
> diff -u -p a/drivers/isdn/act2000/module.c b/drivers/isdn/act2000/module.c
> --- a/drivers/isdn/act2000/module.c
> +++ b/drivers/isdn/act2000/module.c
> @@ -796,7 +796,7 @@ static void __exit act2000_exit(void)
>  	act2000_card *last;
>  	while (card) {
>  		unregister_card(card);
> -		del_timer(&card->ptimer);
> +		del_timer_sync(&card->ptimer);

Correct.

>  		card = card->next;
>  	}
>  	card = cards;
> diff -u -p a/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
> --- a/drivers/net/hamradio/yam.c
> +++ b/drivers/net/hamradio/yam.c
> @@ -1184,7 +1184,7 @@ static void __exit yam_cleanup_driver(vo
>  	struct yam_mcs *p;
>  	int i;
>  
> -	del_timer(&yam_timer);
> +	del_timer_sync(&yam_timer);

Correct.

>  	for (i = 0; i < NR_PORTS; i++) {
>  		struct net_device *dev = yam_devs[i];
>  		if (dev) {
> diff -u -p a/drivers/staging/speakup/main.c b/drivers/staging/speakup/main.c
> --- a/drivers/staging/speakup/main.c
> +++ b/drivers/staging/speakup/main.c
> @@ -2218,7 +2218,7 @@ static void __exit speakup_exit(void)
>  	unregister_keyboard_notifier(&keyboard_notifier_block);
>  	unregister_vt_notifier(&vt_notifier_block);
>  	speakup_unregister_devsynth();
> -	del_timer(&cursor_timer);
> +	del_timer_sync(&cursor_timer);

Not sure about that one as the timer might be rearmed, so the
invocation might need to be further down the cleanup path.

>  	kthread_stop(speakup_task);
>  	speakup_task = NULL;
>  	mutex_lock(&spk_mutex);
> diff -u -p a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
> --- a/drivers/staging/panel/panel.c
> +++ b/drivers/staging/panel/panel.c
> @@ -2298,7 +2298,7 @@ static void __exit panel_cleanup_module(
>  	unregister_reboot_notifier(&panel_notifier);
>  
>  	if (scan_timer.function != NULL)
> -		del_timer(&scan_timer);
> +		del_timer_sync(&scan_timer);

Correct.

>  	if (pprt != NULL) {
>  		if (keypad_enabled) {
> diff -u -p a/drivers/staging/lustre/lustre/llite/super25.c b/drivers/staging/lustre/lustre/llite/super25.c
> --- a/drivers/staging/lustre/lustre/llite/super25.c
> +++ b/drivers/staging/lustre/lustre/llite/super25.c
> @@ -197,7 +197,7 @@ static void __exit exit_lustre_lite(void
>  {
>  	ll_xattr_fini();
>  	vvp_global_fini();
> -	del_timer(&ll_capa_timer);
> +	del_timer_sync(&ll_capa_timer);

Looks wrong, as the timer might be rearmed by the thread which is
not yet stopped.

>  	ll_capa_thread_stop();
>  	LASSERTF(capa_count[CAPA_SITE_CLIENT] == 0,
>  		 "client remaining capa count %d\n",
> diff -u -p a/drivers/atm/idt77105.c b/drivers/atm/idt77105.c
> --- a/drivers/atm/idt77105.c
> +++ b/drivers/atm/idt77105.c
> @@ -369,8 +369,8 @@ EXPORT_SYMBOL(idt77105_init);
>  static void __exit idt77105_exit(void)
>  {
>          /* turn off timers */
> -        del_timer(&stats_timer);
> -        del_timer(&restart_timer);
> +        del_timer_sync(&stats_timer);
> +        del_timer_sync(&restart_timer);

Yep.

>  }
>  
>  module_exit(idt77105_exit);
> diff -u -p a/drivers/atm/nicstar.c b/drivers/atm/nicstar.c
> --- a/drivers/atm/nicstar.c
> +++ b/drivers/atm/nicstar.c
> @@ -306,7 +306,7 @@ static void __exit nicstar_cleanup(void)
>  {
>  	XPRINTK("nicstar: nicstar_cleanup() called.\n");
>  
> -	del_timer(&ns_timer);
> +	del_timer_sync(&ns_timer);
>  

The driver might still be in use, as the devices are shut down via the
pci_unregister_driver() call below. So while it's correct to use
del_timer_sync() it's not clear w/o digging deeper into the code
whether it's actually sufficient.

>  	pci_unregister_driver(&nicstar_driver);
>  
> diff -u -p a/drivers/atm/iphase.c b/drivers/atm/iphase.c
> --- a/drivers/atm/iphase.c
> +++ b/drivers/atm/iphase.c
> @@ -3289,7 +3289,7 @@ static void __exit ia_module_exit(void)
>  {
>  	pci_unregister_driver(&ia_driver);
>  
> -        del_timer(&ia_timer);
> +        del_timer_sync(&ia_timer);

The timer is self rearming and has protection against the removal of
the devices. So it should be fine.

>  }
>  
>  module_init(ia_module_init);
> diff -u -p a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c
> --- a/net/hsr/hsr_main.c
> +++ b/net/hsr/hsr_main.c
> @@ -459,7 +459,7 @@ static int __init hsr_init(void)
>  static void __exit hsr_exit(void)
>  {
>  	unregister_netdevice_notifier(&hsr_nb);
> -	del_timer(&prune_timer);
> +	del_timer_sync(&prune_timer);

Correct as the only rearm is from the timer callback itself

>  	hsr_netlink_exit();
>  	dev_remove_pack(&hsr_pt);
>  }
> diff -u -p a/net/atm/mpc.c b/net/atm/mpc.c
> --- a/net/atm/mpc.c
> +++ b/net/atm/mpc.c
> @@ -1492,7 +1492,7 @@ static void __exit atm_mpoa_cleanup(void
>  
>  	mpc_proc_clean();
>  
> -	del_timer(&mpc_timer);
> +	del_timer_sync(&mpc_timer);

Looks correct as well. Timer is rearming no other dependencies.

>  	unregister_netdevice_notifier(&mpoa_notifier);
>  	deregister_atm_ioctl(&atm_ioctl_ops);

Thanks,

	tglx

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