Re: [PATCH 4.1 39/46] sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-23 Thread Greg Kroah-Hartman 
On Fri, Oct 23, 2015 at 11:14:30PM +0300, Thomas Backlund wrote:
> Den 23.10.2015 kl. 20:46, skrev Greg Kroah-Hartman:
> >4.1-stable review patch.  If anyone has any objections, please let me know.
> >
> >--
> >
> >From: Konstantin Khlebnikov 
> >
> >commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.
> 
> This one broke drivers/xen/  build
> 
> 
> drivers/xen/preempt.c: In function ”xen_maybe_preempt_hcall”:
> drivers/xen/preempt.c:34:11: error: too few arguments to function
> ”should_resched”
> && should_resched())) {
>^
> 
> 
> Needed fix is:
> 
> From 0fa2f5cb2b0ecd8d56baa51f35f09aab234eb0bf Mon Sep 17 00:00:00 2001
> From: Konstantin Khlebnikov 
> Date: Wed, 15 Jul 2015 12:52:01 +0300
> Subject: [PATCH] sched/preempt, xen: Use need_resched() instead of
>  should_resched()

Thanks, now queued up.

greg k-h
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Re: [PATCH 4.1 39/46] sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-23 Thread Thomas Backlund 

Den 23.10.2015 kl. 20:46, skrev Greg Kroah-Hartman:

4.1-stable review patch.  If anyone has any objections, please let me know.

--

From: Konstantin Khlebnikov 

commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.


This one broke drivers/xen/  build


drivers/xen/preempt.c: In function ”xen_maybe_preempt_hcall”:
drivers/xen/preempt.c:34:11: error: too few arguments to function 
”should_resched”

&& should_resched())) {
   ^


Needed fix is:

From 0fa2f5cb2b0ecd8d56baa51f35f09aab234eb0bf Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov 
Date: Wed, 15 Jul 2015 12:52:01 +0300
Subject: [PATCH] sched/preempt, xen: Use need_resched() instead of
 should_resched()


--
Thomas

--
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[PATCH 4.1 39/46] sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-23 Thread Greg Kroah-Hartman 
4.1-stable review patch.  If anyone has any objections, please let me know.

--

From: Konstantin Khlebnikov 

commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.

These functions check should_resched() before unlocking spinlock/bh-enable:
preempt_count always non-zero => should_resched() always returns false.
cond_resched_lock() worked iff spin_needbreak is set.

This patch adds argument "preempt_offset" to should_resched().

preempt_count offset constants for that:

  PREEMPT_DISABLE_OFFSET  - offset after preempt_disable()
  PREEMPT_LOCK_OFFSET - offset after spin_lock()
  SOFTIRQ_DISABLE_OFFSET  - offset after local_bh_distable()
  SOFTIRQ_LOCK_OFFSET - offset after spin_lock_bh()

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Graf 
Cc: Boris Ostrovsky 
Cc: David Vrabel 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: bdb438065890 ("sched: Extract the basic add/sub preempt_count modifiers")
Link: http://lkml.kernel.org/r/20150715095204.12246.98268.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Mike Galbraith 
Signed-off-by: Greg Kroah-Hartman 
---
 arch/x86/include/asm/preempt.h |4 ++--
 include/asm-generic/preempt.h  |5 +++--
 include/linux/preempt.h|5 +++--
 include/linux/preempt_mask.h   |   14 +++---
 include/linux/sched.h  |6 --
 kernel/sched/core.c|6 +++---
 6 files changed, 22 insertions(+), 18 deletions(-)

--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -90,9 +90,9 @@ static __always_inline bool __preempt_co
 /*
  * Returns true when we need to resched and can (barring IRQ state).
  */
-static __always_inline bool should_resched(void)
+static __always_inline bool should_resched(int preempt_offset)
 {
-   return unlikely(!raw_cpu_read_4(__preempt_count));
+   return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
 }
 
 #ifdef CONFIG_PREEMPT
--- a/include/asm-generic/preempt.h
+++ b/include/asm-generic/preempt.h
@@ -71,9 +71,10 @@ static __always_inline bool __preempt_co
 /*
  * Returns true when we need to resched and can (barring IRQ state).
  */
-static __always_inline bool should_resched(void)
+static __always_inline bool should_resched(int preempt_offset)
 {
-   return unlikely(!preempt_count() && tif_need_resched());
+   return unlikely(preempt_count() == preempt_offset &&
+   tif_need_resched());
 }
 
 #ifdef CONFIG_PREEMPT
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -20,7 +20,8 @@
 #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
 extern void preempt_count_add(int val);
 extern void preempt_count_sub(int val);
-#define preempt_count_dec_and_test() ({ preempt_count_sub(1); 
should_resched(); })
+#define preempt_count_dec_and_test() \
+   ({ preempt_count_sub(1); should_resched(0); })
 #else
 #define preempt_count_add(val) __preempt_count_add(val)
 #define preempt_count_sub(val) __preempt_count_sub(val)
@@ -59,7 +60,7 @@ do { \
 
 #define preempt_check_resched() \
 do { \
-   if (should_resched()) \
+   if (should_resched(0)) \
__preempt_schedule(); \
 } while (0)
 
--- a/include/linux/preempt_mask.h
+++ b/include/linux/preempt_mask.h
@@ -71,13 +71,21 @@
  */
 #define in_nmi()   (preempt_count() & NMI_MASK)
 
+/*
+ * The preempt_count offset after preempt_disable();
+ */
 #if defined(CONFIG_PREEMPT_COUNT)
-# define PREEMPT_DISABLE_OFFSET 1
+# define PREEMPT_DISABLE_OFFSETPREEMPT_OFFSET
 #else
-# define PREEMPT_DISABLE_OFFSET 0
+# define PREEMPT_DISABLE_OFFSET0
 #endif
 
 /*
+ * The preempt_count offset after spin_lock()
+ */
+#define PREEMPT_LOCK_OFFSETPREEMPT_DISABLE_OFFSET
+
+/*
  * The preempt_count offset needed for things like:
  *
  *  spin_lock_bh()
@@ -90,7 +98,7 @@
  *
  * Work as expected.
  */
-#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_DISABLE_OFFSET)
+#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET)
 
 /*
  * Are we running in atomic context?  WARNING: this macro cannot
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2834,12 +2834,6 @@ extern int _cond_resched(void);
 
 extern int __cond_resched_lock(spinlock_t *lock);
 
-#ifdef CONFIG_PREEMPT_COUNT
-#define PREEMPT_LOCK_OFFSETPREEMPT_OFFSET
-#else
-#define PREEMPT_LOCK_OFFSET0
-#endif
-
 #define cond_resched_lock(lock) ({ \
___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
__cond_resched_lock(lock);  \
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4232,7 +4232,7 @@ SYSCALL_DEFINE0(sched_yield)
 
 int __sched _cond_resched(void)
 {
-   if (should_resched()) {
+   if (should_resched(0)) {
preempt_schedule_common();
return 1;
}
@@ -4250,7 +4250,7 @@

Re: [PATCH 4.1 39/46] sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-23 Thread Thomas Backlund 

Den 23.10.2015 kl. 20:46, skrev Greg Kroah-Hartman:

4.1-stable review patch.  If anyone has any objections, please let me know.

--

From: Konstantin Khlebnikov 

commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.


This one broke drivers/xen/  build


drivers/xen/preempt.c: In function ”xen_maybe_preempt_hcall”:
drivers/xen/preempt.c:34:11: error: too few arguments to function 
”should_resched”

&& should_resched())) {
   ^


Needed fix is:

From 0fa2f5cb2b0ecd8d56baa51f35f09aab234eb0bf Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov 
Date: Wed, 15 Jul 2015 12:52:01 +0300
Subject: [PATCH] sched/preempt, xen: Use need_resched() instead of
 should_resched()


--
Thomas

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH 4.1 39/46] sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-23 Thread Greg Kroah-Hartman 
On Fri, Oct 23, 2015 at 11:14:30PM +0300, Thomas Backlund wrote:
> Den 23.10.2015 kl. 20:46, skrev Greg Kroah-Hartman:
> >4.1-stable review patch.  If anyone has any objections, please let me know.
> >
> >--
> >
> >From: Konstantin Khlebnikov 
> >
> >commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.
> 
> This one broke drivers/xen/  build
> 
> 
> drivers/xen/preempt.c: In function ”xen_maybe_preempt_hcall”:
> drivers/xen/preempt.c:34:11: error: too few arguments to function
> ”should_resched”
> && should_resched())) {
>^
> 
> 
> Needed fix is:
> 
> From 0fa2f5cb2b0ecd8d56baa51f35f09aab234eb0bf Mon Sep 17 00:00:00 2001
> From: Konstantin Khlebnikov 
> Date: Wed, 15 Jul 2015 12:52:01 +0300
> Subject: [PATCH] sched/preempt, xen: Use need_resched() instead of
>  should_resched()

Thanks, now queued up.

greg k-h
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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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Please read the FAQ at  http://www.tux.org/lkml/

[PATCH 4.1 39/46] sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-23 Thread Greg Kroah-Hartman 
4.1-stable review patch.  If anyone has any objections, please let me know.

--

From: Konstantin Khlebnikov 

commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.

These functions check should_resched() before unlocking spinlock/bh-enable:
preempt_count always non-zero => should_resched() always returns false.
cond_resched_lock() worked iff spin_needbreak is set.

This patch adds argument "preempt_offset" to should_resched().

preempt_count offset constants for that:

  PREEMPT_DISABLE_OFFSET  - offset after preempt_disable()
  PREEMPT_LOCK_OFFSET - offset after spin_lock()
  SOFTIRQ_DISABLE_OFFSET  - offset after local_bh_distable()
  SOFTIRQ_LOCK_OFFSET - offset after spin_lock_bh()

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Graf 
Cc: Boris Ostrovsky 
Cc: David Vrabel 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: bdb438065890 ("sched: Extract the basic add/sub preempt_count modifiers")
Link: http://lkml.kernel.org/r/20150715095204.12246.98268.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Mike Galbraith 
Signed-off-by: Greg Kroah-Hartman 
---
 arch/x86/include/asm/preempt.h |4 ++--
 include/asm-generic/preempt.h  |5 +++--
 include/linux/preempt.h|5 +++--
 include/linux/preempt_mask.h   |   14 +++---
 include/linux/sched.h  |6 --
 kernel/sched/core.c|6 +++---
 6 files changed, 22 insertions(+), 18 deletions(-)

--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -90,9 +90,9 @@ static __always_inline bool __preempt_co
 /*
  * Returns true when we need to resched and can (barring IRQ state).
  */
-static __always_inline bool should_resched(void)
+static __always_inline bool should_resched(int preempt_offset)
 {
-   return unlikely(!raw_cpu_read_4(__preempt_count));
+   return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
 }
 
 #ifdef CONFIG_PREEMPT
--- a/include/asm-generic/preempt.h
+++ b/include/asm-generic/preempt.h
@@ -71,9 +71,10 @@ static __always_inline bool __preempt_co
 /*
  * Returns true when we need to resched and can (barring IRQ state).
  */
-static __always_inline bool should_resched(void)
+static __always_inline bool should_resched(int preempt_offset)
 {
-   return unlikely(!preempt_count() && tif_need_resched());
+   return unlikely(preempt_count() == preempt_offset &&
+   tif_need_resched());
 }
 
 #ifdef CONFIG_PREEMPT
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -20,7 +20,8 @@
 #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
 extern void preempt_count_add(int val);
 extern void preempt_count_sub(int val);
-#define preempt_count_dec_and_test() ({ preempt_count_sub(1); 
should_resched(); })
+#define preempt_count_dec_and_test() \
+   ({ preempt_count_sub(1); should_resched(0); })
 #else
 #define preempt_count_add(val) __preempt_count_add(val)
 #define preempt_count_sub(val) __preempt_count_sub(val)
@@ -59,7 +60,7 @@ do { \
 
 #define preempt_check_resched() \
 do { \
-   if (should_resched()) \
+   if (should_resched(0)) \
__preempt_schedule(); \
 } while (0)
 
--- a/include/linux/preempt_mask.h
+++ b/include/linux/preempt_mask.h
@@ -71,13 +71,21 @@
  */
 #define in_nmi()   (preempt_count() & NMI_MASK)
 
+/*
+ * The preempt_count offset after preempt_disable();
+ */
 #if defined(CONFIG_PREEMPT_COUNT)
-# define PREEMPT_DISABLE_OFFSET 1
+# define PREEMPT_DISABLE_OFFSETPREEMPT_OFFSET
 #else
-# define PREEMPT_DISABLE_OFFSET 0
+# define PREEMPT_DISABLE_OFFSET0
 #endif
 
 /*
+ * The preempt_count offset after spin_lock()
+ */
+#define PREEMPT_LOCK_OFFSETPREEMPT_DISABLE_OFFSET
+
+/*
  * The preempt_count offset needed for things like:
  *
  *  spin_lock_bh()
@@ -90,7 +98,7 @@
  *
  * Work as expected.
  */
-#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_DISABLE_OFFSET)
+#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET)
 
 /*
  * Are we running in atomic context?  WARNING: this macro cannot
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2834,12 +2834,6 @@ extern int _cond_resched(void);
 
 extern int __cond_resched_lock(spinlock_t *lock);
 
-#ifdef CONFIG_PREEMPT_COUNT
-#define PREEMPT_LOCK_OFFSETPREEMPT_OFFSET
-#else
-#define PREEMPT_LOCK_OFFSET0
-#endif
-
 #define cond_resched_lock(lock) ({ \
___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
__cond_resched_lock(lock);  \
---