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Subject[PATCH] RFC: change do_timer() to take xtime lock, and provide do_timer_locked()
Date
in an effort to reduce occurrences of xtime_lock in the codebase,
this commit makes do_timer take the xtime lock.

there are quite some occurences where arch code seems to protect
other datastructures with this lock too.
we provide do_timer_locked() for these occurences.

however, for this change to make sense, we should try to get rid
of most calls to do_timer_locked()
gonna try to address that in other arch specific commits.

Signed-off-by: Torben Hohn <torbenh@gmx.de>
---
arch/alpha/kernel/time.c | 2 +-
arch/arm/kernel/time.c | 4 ++--
arch/arm/mach-clps711x/include/mach/time.h | 2 ++
arch/blackfin/kernel/time.c | 3 +--
arch/cris/arch-v10/kernel/time.c | 1 +
arch/cris/arch-v32/kernel/time.c | 4 ++--
arch/frv/kernel/time.c | 2 +-
arch/h8300/kernel/time.c | 3 +--
arch/ia64/kernel/time.c | 2 +-
arch/ia64/xen/time.c | 2 +-
arch/m32r/kernel/time.c | 2 +-
arch/m68k/kernel/time.c | 1 +
arch/m68k/sun3/sun3ints.c | 1 +
arch/m68knommu/kernel/time.c | 5 +----
arch/mn10300/kernel/time.c | 2 +-
arch/parisc/kernel/time.c | 3 +--
arch/sparc/kernel/pcic.c | 2 +-
arch/sparc/kernel/time_32.c | 2 +-
arch/xtensa/kernel/time.c | 2 +-
include/linux/sched.h | 1 +
kernel/time/tick-common.c | 2 +-
kernel/time/tick-sched.c | 2 +-
kernel/timer.c | 9 ++++++++-
23 files changed, 33 insertions(+), 26 deletions(-)

diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index c1f3e7c..843344f 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -187,7 +187,7 @@ irqreturn_t timer_interrupt(int irq, void *dev)
nticks = delta >> FIX_SHIFT;

if (nticks)
- do_timer(nticks);
+ do_timer_locked(nticks);

write_sequnlock(&xtime_lock);

diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index 3d76bf2..ff83e3d 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -107,9 +107,9 @@ void timer_tick(void)
{
profile_tick(CPU_PROFILING);
do_leds();
- write_seqlock(&xtime_lock);
+
+ /* do_timer takes the xtime_lock itself now */
do_timer(1);
- write_sequnlock(&xtime_lock);
#ifndef CONFIG_SMP
update_process_times(user_mode(get_irq_regs()));
#endif
diff --git a/arch/arm/mach-clps711x/include/mach/time.h b/arch/arm/mach-clps711x/include/mach/time.h
index 8fe283c..b4fa8f7 100644
--- a/arch/arm/mach-clps711x/include/mach/time.h
+++ b/arch/arm/mach-clps711x/include/mach/time.h
@@ -30,6 +30,8 @@ p720t_timer_interrupt(int irq, void *dev_id)
{
struct pt_regs *regs = get_irq_regs();
do_leds();
+
+ /* do_timer takes the xtime_lock itself now */
do_timer(1);
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
diff --git a/arch/blackfin/kernel/time.c b/arch/blackfin/kernel/time.c
index c911361..2224697 100644
--- a/arch/blackfin/kernel/time.c
+++ b/arch/blackfin/kernel/time.c
@@ -121,9 +121,8 @@ __attribute__((l1_text))
#endif
irqreturn_t timer_interrupt(int irq, void *dummy)
{
- write_seqlock(&xtime_lock);
+ /* do_timer takes the xtime_lock itself now */
do_timer(1);
- write_sequnlock(&xtime_lock);

#ifdef CONFIG_IPIPE
update_root_process_times(get_irq_regs());
diff --git a/arch/cris/arch-v10/kernel/time.c b/arch/cris/arch-v10/kernel/time.c
index 00eb36f..e4d4352 100644
--- a/arch/cris/arch-v10/kernel/time.c
+++ b/arch/cris/arch-v10/kernel/time.c
@@ -176,6 +176,7 @@ timer_interrupt(int irq, void *dev_id)

/* call the real timer interrupt handler */

+ /* do_timer takes the xtime_lock itself now */
do_timer(1);

cris_do_profile(regs); /* Save profiling information */
diff --git a/arch/cris/arch-v32/kernel/time.c b/arch/cris/arch-v32/kernel/time.c
index a545211..997dc08 100644
--- a/arch/cris/arch-v32/kernel/time.c
+++ b/arch/cris/arch-v32/kernel/time.c
@@ -216,9 +216,9 @@ static inline irqreturn_t timer_interrupt(int irq, void *dev_id)
return IRQ_HANDLED;

/* Call the real timer interrupt handler */
- write_seqlock(&xtime_lock);
+
+ /* do_timer takes the xtime_lock itself now */
do_timer(1);
- write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}

diff --git a/arch/frv/kernel/time.c b/arch/frv/kernel/time.c
index 0ddbbae..f28d68c 100644
--- a/arch/frv/kernel/time.c
+++ b/arch/frv/kernel/time.c
@@ -64,7 +64,7 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)
*/
write_seqlock(&xtime_lock);

- do_timer(1);
+ do_timer_locked(1);

#ifdef CONFIG_HEARTBEAT
static unsigned short n;
diff --git a/arch/h8300/kernel/time.c b/arch/h8300/kernel/time.c
index 165005a..b27c93d 100644
--- a/arch/h8300/kernel/time.c
+++ b/arch/h8300/kernel/time.c
@@ -35,9 +35,8 @@ void h8300_timer_tick(void)
{
if (current->pid)
profile_tick(CPU_PROFILING);
- write_seqlock(&xtime_lock);
+ /* do_timer takes the xtime_lock itself now */
do_timer(1);
- write_sequnlock(&xtime_lock);
update_process_times(user_mode(get_irq_regs()));
}

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 9702fa9..7140493 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -198,7 +198,7 @@ timer_interrupt (int irq, void *dev_id)
* xtime_lock.
*/
write_seqlock(&xtime_lock);
- do_timer(1);
+ do_timer_locked(1);
local_cpu_data->itm_next = new_itm;
write_sequnlock(&xtime_lock);
} else
diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c
index c1c5445..0573a04 100644
--- a/arch/ia64/xen/time.c
+++ b/arch/ia64/xen/time.c
@@ -141,7 +141,7 @@ consider_steal_time(unsigned long new_itm)

if (cpu == time_keeper_id) {
write_seqlock(&xtime_lock);
- do_timer(stolen + blocked);
+ do_timer_locked(stolen + blocked);
local_cpu_data->itm_next = delta_itm + new_itm;
write_sequnlock(&xtime_lock);
} else {
diff --git a/arch/m32r/kernel/time.c b/arch/m32r/kernel/time.c
index bda8682..5586ee5 100644
--- a/arch/m32r/kernel/time.c
+++ b/arch/m32r/kernel/time.c
@@ -114,7 +114,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
#ifndef CONFIG_SMP
profile_tick(CPU_PROFILING);
#endif
- /* XXX FIXME. Uh, the xtime_lock should be held here, no? */
+ /* do_timer() gets the xtime lock now */
do_timer(1);

#ifndef CONFIG_SMP
diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c
index 06438da..7f3a01b1 100644
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -41,6 +41,7 @@ static inline int set_rtc_mmss(unsigned long nowtime)
*/
static irqreturn_t timer_interrupt(int irq, void *dummy)
{
+ /* do_timer takes the xtime_lock now */
do_timer(1);
update_process_times(user_mode(get_irq_regs()));
profile_tick(CPU_PROFILING);
diff --git a/arch/m68k/sun3/sun3ints.c b/arch/m68k/sun3/sun3ints.c
index 2d9e21b..ce1742c 100644
--- a/arch/m68k/sun3/sun3ints.c
+++ b/arch/m68k/sun3/sun3ints.c
@@ -66,6 +66,7 @@ static irqreturn_t sun3_int5(int irq, void *dev_id)
#ifdef CONFIG_SUN3
intersil_clear();
#endif
+ /* do_timer takes the xtime_lock now */
do_timer(1);
update_process_times(user_mode(get_irq_regs()));
if (!(kstat_cpu(0).irqs[irq] % 20))
diff --git a/arch/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c
index d6ac2a4..d45eebb 100644
--- a/arch/m68knommu/kernel/time.c
+++ b/arch/m68knommu/kernel/time.c
@@ -44,12 +44,9 @@ irqreturn_t arch_timer_interrupt(int irq, void *dummy)
if (current->pid)
profile_tick(CPU_PROFILING);

- write_seqlock(&xtime_lock);
-
+ /* do_timer takes the xtime_lock now */
do_timer(1);

- write_sequnlock(&xtime_lock);
-
update_process_times(user_mode(get_irq_regs()));

return(IRQ_HANDLED);
diff --git a/arch/mn10300/kernel/time.c b/arch/mn10300/kernel/time.c
index 75da468..420feeb 100644
--- a/arch/mn10300/kernel/time.c
+++ b/arch/mn10300/kernel/time.c
@@ -114,7 +114,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
mn10300_last_tsc += MN10300_TSC_PER_HZ;

/* advance the kernel's time tracking system */
- do_timer(1);
+ do_timer_locked(1);
}

write_sequnlock(&xtime_lock);
diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
index 05511cc..c77ab78 100644
--- a/arch/parisc/kernel/time.c
+++ b/arch/parisc/kernel/time.c
@@ -163,9 +163,8 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
}

if (cpu == 0) {
- write_seqlock(&xtime_lock);
+ /* do_timer takes the xtime_lock */
do_timer(ticks_elapsed);
- write_sequnlock(&xtime_lock);
}

return IRQ_HANDLED;
diff --git a/arch/sparc/kernel/pcic.c b/arch/sparc/kernel/pcic.c
index aeaa09a..1eb27ed 100644
--- a/arch/sparc/kernel/pcic.c
+++ b/arch/sparc/kernel/pcic.c
@@ -702,7 +702,7 @@ static irqreturn_t pcic_timer_handler (int irq, void *h)
{
write_seqlock(&xtime_lock); /* Dummy, to show that we remember */
pcic_clear_clock_irq();
- do_timer(1);
+ do_timer_locked(1);
write_sequnlock(&xtime_lock);
#ifndef CONFIG_SMP
update_process_times(user_mode(get_irq_regs()));
diff --git a/arch/sparc/kernel/time_32.c b/arch/sparc/kernel/time_32.c
index 9c743b1..b998602 100644
--- a/arch/sparc/kernel/time_32.c
+++ b/arch/sparc/kernel/time_32.c
@@ -101,7 +101,7 @@ static irqreturn_t timer_interrupt(int dummy, void *dev_id)

clear_clock_irq();

- do_timer(1);
+ do_timer_locked(1);

write_sequnlock(&xtime_lock);

diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index 19df764..9a13249 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -98,7 +98,7 @@ again:

write_seqlock(&xtime_lock);

- do_timer(1); /* Linux handler in kernel/timer.c */
+ do_timer_locked(1); /* Linux handler in kernel/timer.c */

/* Note that writing CCOMPARE clears the interrupt. */

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d747f94..8659219 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2050,6 +2050,7 @@ extern void release_uids(struct user_namespace *ns);
#include <asm/current.h>

extern void do_timer(unsigned long ticks);
+extern void do_timer_locked(unsigned long ticks);

extern int wake_up_state(struct task_struct *tsk, unsigned int state);
extern int wake_up_process(struct task_struct *tsk);
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 051bc80..e2ec6df 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -65,7 +65,7 @@ static void tick_periodic(int cpu)
/* Keep track of the next tick event */
tick_next_period = ktime_add(tick_next_period, tick_period);

- do_timer(1);
+ do_timer_locked(1);
write_sequnlock(&xtime_lock);
}

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 3e216e0..4e6a323 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -75,7 +75,7 @@ static void tick_do_update_jiffies64(ktime_t now)
last_jiffies_update = ktime_add_ns(last_jiffies_update,
incr * ticks);
}
- do_timer(++ticks);
+ do_timer_locked(++ticks);

/* Keep the tick_next_period variable up to date */
tick_next_period = ktime_add(last_jiffies_update, tick_period);
diff --git a/kernel/timer.c b/kernel/timer.c
index 43ca993..ddc724c 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1299,13 +1299,20 @@ void run_local_timers(void)
* jiffies is defined in the linker script...
*/

-void do_timer(unsigned long ticks)
+void do_timer_locked(unsigned long ticks)
{
jiffies_64 += ticks;
update_wall_time();
calc_global_load(ticks);
}

+void do_timer(unsigned long ticks)
+{
+ write_seqlock(&xtime_lock);
+ do_timer_locked(ticks);
+ write_sequnlock(&xtime_lock);
+}
+
#ifdef __ARCH_WANT_SYS_ALARM

/*
--
1.7.2.3


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