Commit 58e1177b authored Oct 04, 2017 by Kees Cook Committed by Thomas Gleixner Oct 05, 2017

timer: Convert schedule_timeout() to use from_timer()



In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new from_timer() helper and passing
the timer pointer explicitly. Since this special timer is on the stack, it
needs to have a wrapper structure to carry state once .data is eliminated.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: Petr Mladek <pmladek@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux1394-devel@lists.sourceforge.net
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-s390@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Harish Patil <harish.patil@cavium.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Manish Chopra <manish.chopra@cavium.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-pm@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Gross <mark.gross@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Michael Reed <mdr@sgi.com>
Cc: netdev@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lkml.kernel.org/r/1507159627-127660-2-git-send-email-keescook@chromium.org

parent 26eafeaa

include/linux/timer.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -179,6 +179,14 @@ static inline void timer_setup(struct timer_list *timer,
		(TIMER_DATA_TYPE)timer, flags);
		}

		static inline void timer_setup_on_stack(struct timer_list *timer,
		void (callback)(struct timer_list ),
		unsigned int flags)
		{
		__setup_timer_on_stack(timer, (TIMER_FUNC_TYPE)callback,
		(TIMER_DATA_TYPE)timer, flags);
		}

		#define from_timer(var, callback_timer, timer_fieldname) \
		container_of(callback_timer, typeof(*var), timer_fieldname)

kernel/time/timer.c

+19 −7

Original line number	Diff line number	Diff line
		@@ -1668,9 +1668,20 @@ void run_local_timers(void)
		raise_softirq(TIMER_SOFTIRQ);
		}

		static void process_timeout(unsigned long __data)
		/*
		* Since schedule_timeout()'s timer is defined on the stack, it must store
		* the target task on the stack as well.
		*/
		struct process_timer {
		struct timer_list timer;
		struct task_struct *task;
		};

		static void process_timeout(struct timer_list *t)
		{
		wake_up_process((struct task_struct *)__data);
		struct process_timer *timeout = from_timer(timeout, t, timer);

		wake_up_process(timeout->task);
		}

		/**
		@@ -1704,7 +1715,7 @@ static void process_timeout(unsigned long __data)
		*/
		signed long __sched schedule_timeout(signed long timeout)
		{
		struct timer_list timer;
		struct process_timer timer;
		unsigned long expire;

		switch (timeout)
		@@ -1738,13 +1749,14 @@ signed long __sched schedule_timeout(signed long timeout)

		expire = timeout + jiffies;

		setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
		__mod_timer(&timer, expire, false);
		timer.task = current;
		timer_setup_on_stack(&timer.timer, process_timeout, 0);
		__mod_timer(&timer.timer, expire, false);
		schedule();
		del_singleshot_timer_sync(&timer);
		del_singleshot_timer_sync(&timer.timer);

		/* Remove the timer from the object tracker */
		destroy_timer_on_stack(&timer);
		destroy_timer_on_stack(&timer.timer);

		timeout = expire - jiffies;